AWT: CONTROLS, LAYOUT MANAGERS AND MENUS
What is meant by Controls and what are different types of controls?
Ans : Controls are componenets that allow a user to interact with your application.
The AWT supports the following types of controls:
Labels
Push buttons
Check boxes
Choice lists
Lists
Scroll bars
Text components
These controls are subclasses of Component.
You want to construct a text area that is 80 character-widths wide and 10 character-heights tall. What code do you use?
new TextArea(80, 10)
new TextArea(10, 80)
Ans: b.
A text field has a variable-width font. It is constructed by calling new
TextField("iiiii"). What happens if you change the contents of the text field to
"wwwww"? (Bear in mind that is one of the narrowest characters, and w is one of the widest.)
The text field becomes wider.
The text field becomes narrower.
The text field stays the same width; to see the entire contents you will have to scroll by using the ß and à keys.
The text field stays the same width; to see the entire contents you will have to scroll by using the text field’s horizontal scroll bar.
Ans : c.
The CheckboxGroup class is a subclass of the Component class.
True
False
Ans : b.
5) What are the immediate super classes of the following classes?
a) Container class
b) MenuComponent class
c) Dialog class
d) Applet class
e) Menu class
Ans : a) Container - Component
b) MenuComponent - Object
c) Dialog - Window
d) Applet - Panel
e) Menu - MenuItem
6) What are the SubClass of Textcomponent Class?
Ans : TextField and TextArea
7) Which method of the component class is used to set the position and the size of a component?
Ans : setBounds()
8) Which TextComponent method is used to set a TextComponent to the read-only state?
Ans : setEditable()
9) How can the Checkbox class be used to create a radio button?
Ans : By associating Checkbox objects with a CheckboxGroup.
10) What Checkbox method allows you to tell if a Checkbox is checked?
Ans : getState()
11) Which Component method is used to access a component's immediate Container?
getVisible()
getImmediate
getParent()
getContainer
Ans : c.
12) What methods are used to get and set the text label displayed by a Button object?
Ans : getLabel( ) and setLabel( )
13) What is the difference between a Choice and a List?
Ans : A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice.
A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.
14) Which Container method is used to cause a container to be laid out and redisplayed?
Ans : validate( )
15) What is the difference between a Scollbar and a Scrollpane?
Ans : A Scrollbar is a Component, but not a Container.
A Scrollpane is a Container and handles its own events and performs its own
scrolling.
16) Which Component subclass is used for drawing and painting?
Ans : Canvas.
17) Which of the following are direct or indirect subclasses of Component?
Button
Label
CheckboxMenuItem
Toolbar
Frame
Ans : a, b and e.
18) Which of the following are direct or indirect subclasses of Container?
Frame
TextArea
MenuBar
FileDialog
Applet
Ans : a,d and e.
19) Which method is used to set the text of a Label object?
setText( )
setLabel( )
setTextLabel( )
setLabelText( )
Ans : a.
20) Which constructor creates a TextArea with 10 rows and 20 columns?
new TextArea(10, 20)
new TextArea(20, 10)
new TextArea(new Rows(10), new columns(20))
new TextArea(200)
Ans : a.
(Usage is TextArea(rows, columns)
21) Which of the following creates a List with 5 visible items and multiple selection enabled?
new List(5, true)
new List(true, 5)
new List(5, false)
new List(false,5)
Ans : a.
[Usage is List(rows, multipleMode)]
22) Which are true about the Container class?
The validate( ) method is used to cause a Container to be laid out and redisplayed.
The add( ) method is used to add a Component to a Container.
The getBorder( ) method returns information about a Container’s insets.
The getComponent( ) method is used to access a Component that is contained in a Container.
Ans : a, b and d.
23) Suppose a Panel is added to a Frame and a Button is added to the Panel. If the Frame’s font is set to 12-point TimesRoman, the Panel’s font is set to 10-point TimesRoman, and the Button’s font is not set, what font will be used to dispaly the Button’s label?
12-point TimesRoman
11-point TimesRoman
10-point TimesRoman
9-point TimesRoman
Ans : c.
A Frame’s background color is set to Color.Yellow, and a Button’s background color is to Color.Blue. Suppose the Button is added to a Panel, which is added to the Frame. What background color will be used with the Panel?
Color.Yellow
Color.Blue
Color.Green
Color.White
Ans : a.
25) Which method will cause a Frame to be displayed?
show( )
setVisible( )
display( )
displayFrame( )
Ans : a and b.
26) All the componenet classes and container classes are derived from _________
class.
Ans : Object.
27) Which method of the container class can be used to add components to a Panel.
Ans : add ( ) method.
28) What are the subclasses of the Container class?
Ans : The Container class has three major subclasses. They are :
Window
Panel
ScrollPane
29) The Choice component allows multiple selection.
True.
False.
Ans : b.
30) The List component does not generate any events.
True.
False.
Ans : b.
31) Which components are used to get text input from the user.
Ans : TextField and TextArea.
32) Which object is needed to group Checkboxes to make them exclusive?
Ans : CheckboxGroup.
33) Which of the following components allow multiple selections?
Non-exclusive Checkboxes.
Radio buttons.
Choice.
List.
Ans : a and d.
34) What are the types of Checkboxes and what is the difference between them?
Ans : Java supports two types of Checkboxes. They are : Exclusive and Non-exclusive.
In case of exclusive Checkboxes, only one among a group of items can be selected at a time. I f an item from the group is selected, the checkbox currently checked is deselected and the new selection is highlighted. The exclusive Checkboxes are also called as Radio buttons.
The non-exclusive checkboxes are not grouped together and each one can be selected independent of the other.
35) What is a Layout Manager and what are the different Layout Managers available in java.awt and what is the default Layout manager for the panel and the panel subclasses?
Ans: A layout Manager is an object that is used to organize components in a container.
The different layouts available in java.awt are :
FlowLayout, BorderLayout, CardLayout, GridLayout and GridBag Layout.
The default Layout Manager of Panal and Panal sub classes is FlowLayout".
36) Can I exert control over the size and placement of components in my interface?
Ans : Yes.
myPanal.setLayout(null);
myPanal.setbounds(20,20,200,200);
37) Can I add the same component to more than one container?
Ans : No. Adding a component to a container automatically removes it from any previous parent(container).
38) How do I specify where a window is to be placed?
Ans : Use setBounds, setSize, or setLocation methods to implement this.
setBounds(int x, int y, int width, int height)
setBounds(Rectangle r)
setSize(int width, int height)
setSize(Dimension d)
setLocation(int x, int y)
setLocation(Point p)
39) How can we create a borderless window?
Ans : Create an instance of the Window class, give it a size, and show it on the screen.
eg. Frame aFrame = ......
Window aWindow = new Window(aFrame);
aWindow.setLayout(new FlowLayout());
aWindow.add(new Button("Press Me"));
aWindow.getBounds(50,50,200,200);
aWindow.show();
40) Can I create a non-resizable windows? If so, how?
Ans: Yes. By using setResizable() method in class Frame.
41) What is the default Layout Manager for the Window and Window subclasses (Frame,Dialog)?
Ans : BorderLayout().
42) How are the elements of different layouts organized?
Ans : FlowLayout : The elements of a FlowLayout are organized in a top to bottom, left to right fashion.
BorderLayout : The elements of a BorderLayout are organized at the
borders (North, South, East and West) and the center of a
container.
CardLayout : The elements of a CardLayout are stacked, one on top of the other, like a deck of cards.
GridLayout : The elements of a GridLayout are of equal size and are laid out using the square of a grid.
GridBagLayout : The elements of a GridBagLayout are organized according to a grid.However, the elements are of different sizes and may occupy
more than one row or column of the grid. In addition, the rows and columns may have different sizes.
43) Which containers use a BorderLayout as their default layout?
Ans : The Window, Frame and Dialog classes use a BorderLayout as their default layout.
44) Which containers use a FlowLayout as their default layout?
Ans : The Panel and the Applet classes use the FlowLayout as their default layout.
45) What is the preferred size of a component?
Ans : The preferred size of a component size that will allow the component to display normally.
46) Which method is method to set the layout of a container?
startLayout( )
initLayout( )
layoutContainer( )
setLayout( )
Ans : d.
47) Which method returns the preferred size of a component?
getPreferredSize( )
getPreferred( )
getRequiredSize( )
getLayout( )
Ans : a.
48) Which layout should you use to organize the components of a container in a
tabular form?
CardLayout
BorederLayout
FlowLayout
GridLayout
Ans : d.
An application has a frame that uses a Border layout manager. Why is it probably not a good idea to put a vertical scroll bar at North in the frame?
The scroll bar’s height would be its preferred height, which is not likely to be enough.
The scroll bar’s width would be the entire width of the frame, which would be much wider than necessary.
Both a and b.
Neither a nor b. There is no problem with the layout as described.
Ans : c.
What is the default layouts for a applet, a frame and a panel?
Ans : For an applet and a panel, Flow layout is the default layout, whereas Border layout is default layout for a frame.
If a frame uses a Grid layout manager and does not contain any panels, then all the components within the frame are the same width and height.
True
False.
Ans : a.
If a frame uses its default layout manager and does not contain any panels, then all the components within the frame are the same width and height.
True
False.
Ans : b.
With a Border layout manager, the component at Center gets all the space that is left over, after the components at North and South have been considered.
True
False
Ans : b.
An Applet has its Layout Manager set to the default of FlowLayout. What code would be the correct to change to another Layout Manager?
setLayoutManager(new GridLayout());
setLayout(new GridLayout(2,2));
c) setGridLayout(2,2,))
d setBorderLayout();
Ans : b.
55) How do you indicate where a component will be positioned using Flowlayout?
a) North, South,East,West
b) Assign a row/column grid reference
c) Pass a X/Y percentage parameter to the add method
d) Do nothing, the FlowLayout will position the component
Ans :d.
56) How do you change the current layout manager for a container?
a) Use the setLayout method
b) Once created you cannot change the current layout manager of a component
c) Use the setLayoutManager method
d) Use the updateLayout method
Ans :a.
57)When using the GridBagLayout manager, each new component requires a new instance of the GridBagConstraints class. Is this statement true or false?
a) true
b) false
Ans : b.
58) Which of the following statements are true?
a)The default layout manager for an Applet is FlowLayout
b) The default layout manager for an application is FlowLayout
c) A layout manager must be assigned to an Applet before the setSize method is called
d) The FlowLayout manager attempts to honor the preferred size of any components
Ans : a and d.
59) Which method does display the messages whenever there is an item selection or deselection of the CheckboxMenuItem menu?
Ans : itemStateChanged method.
60) Which is a dual state menu item?
Ans : CheckboxMenuItem.
61) Which method can be used to enable/diable a checkbox menu item?
Ans : setState(boolean).
Which of the following may a menu contain?
A separator
A check box
A menu
A button
A panel
Ans : a and c.
Which of the following may contain a menu bar?
A panel
A frame
An applet
A menu bar
A menu
Ans : b
64) What is the difference between a MenuItem and a CheckboxMenuItem?
Ans : The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked.
65) Which of the following are true?
A Dialog can have a MenuBar.
MenuItem extends Menu.
A MenuItem can be added to a Menu.
A Menu can be added to a Menu.
Ans : c and d.
Which colour is used to indicate instance methods in the standard "javadoc" format documentation:
1) blue
2) red
3) purple
4) orange
Answer : 2
Explain In JDK 1.1 the variabels, methods and constructors are colour coded to simplifytheir identification.
endExplain
What is the correct ordering for the import, class and package declarations when found in a single file?
1) package, import, class
2) class, import, package
3) import, package, class
4) package, class, import
Answer : 1
Which methods can be legally applied to a string object?
(Multiple)
1) equals(String)
2) equals(Object)
3) trim()
4) round()
5) toString()
Answer : 1,2,3,5
What is the parameter specification for the public static void main method?
(multiple)
1) String args []
2) String [] args
3) Strings args []
4) String args
Answer : 1,2
What does the zeroth element of the string array passed to the public static void main method contain?
(multiple)
1) The name of the program
2) The number of arguments
3) The first argument if one is present
Answer : 3
Which of the following are Java keywords?
(multiple)
1) goto
2) malloc
3) extends
4) FALSE
Answer : 3
What will be the result of compiling the following code:
public class Test {
public static void main (String args []) {
int age;
age = age + 1;
System.out.println("The age is " + age);
}
}
1) Compiles and runs with no output
2) Compiles and runs printing out The age is 1
3) Compiles but generates a runtime error
4) Does not compile
5) Compiles but generates a compile time error
Answer : 4
Which of these is the correct format to use to create the literal char value a?
(multiple)
1) 'a'
2) "a"
3) new Character(a)
4) \000a
Answer : 1
What is the legal range of a byte integral type?
1) 0 - 65, 535
2) (-128) - 127
3) (-32,768) - 32,767
4) (-256) - 255
Answer : 2
Which of the following is illegal:
1) int i = 32;
2) float f = 45.0;
3) double d = 45.0;
Answer 2
What will be the result of compiling the following code:
public class Test {
static int age;
public static void main (String args []) {
age = age + 1;
System.out.println("The age is " + age);
}
}
1) Compiles and runs with no output
2) Compiles and runs printing out The age is 1
3) Compiles but generates a runtime error
4) Does not compile
5) Compiles but generates a compile time error
Answer : 2
Which of the following are correct?
(multiple)
1) 128 >> 1 gives 64
2) 128 >>> 1 gives 64
3) 128 >> 1 gives -64
4) 128 >>> 1 gives -64
Answer : 1
Which of the following return true?
(multiple)
1) "john" == new String("john")
2) "john".equals("john")
3) "john" = "john"
4) "john".equals(new Button("john"))
Answer : 2
Which of the following do not lead to a runtime error?
(multiple)
1) "john" + " was " + " here"
2) "john" + 3
3) 3 + 5
4) 5 + 5.5
answer 1,2,3,4
Which of the following are so called "short circuit" logical operators?
(multiple)
1) &
2) ||
3) &&
4) |
Answer : 2,3
Which of the following are acceptable?
(multiple)
1) Object o = new Button("A");
2) Boolean flag = true;
3) Panel p = new Frame();
4) Frame f = new Panel();
5) Panel p = new Applet();
Answer : 1,5
What is the result of compiling and running the following code:
public class Test {
static int total = 10;
public static void main (String args []) {
new Test();
}
public Test () {
System.out.println("In test");
System.out.println(this);
int temp = this.total;
if (temp > 5) {
System.out.println(temp);
}
}
}
(multiple)
1) The class will not compile
2) The compiler reports and error at line 2
3) The compiler reports an error at line 9
4) The value 10 is one of the elements printed to the standard output
5) The class compiles but generates a runtime error
Answer : 4
Which of the following is correct:
1) String temp [] = new String {"j" "a" "z"};
2) String temp [] = { "j " " b" "c"};
3) String temp = {"a", "b", "c"};
4) String temp [] = {"a", "b", "c"};
Answer 4
What is the correct declaration of an abstract method that is intended to be public:
1) public abstract void add();
2) public abstract void add() {}
3) public abstract add();
4) public virtual add();
Answer : 1
Under what situations do you obtain a default constructor?
1) When you define any class
2) When the class has no other constructors
3) When you define at least one constructor
Answer : 2
Which of the following can be used to define a constructor for this class, given the following code:
public class Test {
...
}
1) public void Test() {...}
2) public Test() {...}
3) public static Test() {...}
4) public static void Test() {...}
Answer : 2
Which of the following are acceptable to the Java compiler:
(multiple)
1) if (2 == 3) System.out.println("Hi");
2) if (2 = 3) System.out.println("Hi");
3) if (true) System.out.println("Hi");
4) if (2 != 3) System.out.println("Hi");
5) if (aString.equals("hello")) System.out.println("Hi");
Answer : 1,3,4,5
Assuming a method contains code which may raise an Exception (but not a RuntimeException), what is the correct way for a method to indicate that it expects the caller to handle that exception:
1) throw Exception
2) throws Exception
3) new Exception
4) Don't need to specify anything
Answer : 2
What is the result of executing the following code, using the parameters 4 and 0:
public void divide(int a, int b) {
try {
int c = a / b;
} catch (Exception e) {
System.out.print("Exception ");
} finally {
System.out.println("Finally");
}
1) Prints out: Exception Finally
2) Prints out: Finally
3) Prints out: Exception
4) No output
Answer : 1
Which of the following is a legal return type of a method overloading the following method:
public void add(int a) {...}
1) void
2) int
3) Can be anything
Answer : 3
Which of the following statements is correct for a method which is overriding the following method:
public void add(int a) {...}
1) the overriding method must return void
2) the overriding method must return int
3) the overriding method can return whatever it likes
Answer : 1
Given the following classes defined in separate files, what will be the effect of compiling and running this class Test?
class Vehicle {
public void drive() {
System.out.println("Vehicle: drive");
}
}
class Car extends Vehicle {
public void drive() {
System.out.println("Car: drive");
}
}
public class Test {
public static void main (String args []) {
Vehicle v;
Car c;
v = new Vehicle();
c = new Car();
v.drive();
c.drive();
v = c;
v.drive();
}
}
1) Generates a Compiler error on the statement v= c;
2) Generates runtime error on the statement v= c;
3) Prints out:
Vehicle: drive
Car: drive
Car: drive
4) Prints out:
Vehicle: drive
Car: drive
Vehicle: drive
Answer : 3
Where in a constructor, can you place a call to a constructor defined in the super class?
1) Anywhere
2) The first statement in the constructor
3) The last statement in the constructor
4) You can't call super in a constructor
Answer : 2
Which variables can an inner class access from the class which encapsulates it?
(multiple)
1) All static variables
2) All final variables
3) All instance variables
4) Only final instance variables
5) Only final static variables
Answer : 1,2,3
What class must an inner class extend:
1) The top level class
2) The Object class
3) Any class or interface
4) It must extend an interface
Answer 3
In the following code, which is the earliest statement, where the object originally held in e, may be garbage collected:
1. public class Test {
2. public static void main (String args []) {
3. Employee e = new Employee("Bob", 48);
4. e.calculatePay();
5. System.out.println(e.printDetails());
6. e = null;
7. e = new Employee("Denise", 36);
8. e.calculatePay();
9. System.out.println(e.printDetails());
10. }
11. }
1) Line 10
2) Line 11
3) Line 7
4) Line 8
5) Never
Answer : 3
What is the name of the interface that can be used to define a class that can execute within its own thread?
1) Runnable
2) Run
3) Threadable
4) Thread
5) Executable
Answer : 1
What is the name of the method used to schedule a thread for execution?
1) init();
2) start();
3) run();
4) resume();
5) sleep();
Answer : 2
Which methods may cause a thread to stop executing?
(multiple)
1) sleep();
2) stop();
3) yield();
4) wait();
5) notify();
6) notifyAll()
7) synchronized()
Answer : 1,2,3,4
Which of the following would create a text field able to display 10 characters (assuming a fixed size font) displaying the initial string "hello":
1) new TextField("hello", 10);
2) new TextField("hello");
3) new textField(10);
4) new TextField();
Answer : 1
Which of the following methods are defined on the Graphics class:
(multiple)
1) drawLine(int, int, int, int)
2) drawImage(Image, int, int, ImageObserver)
3) drawString(String, int, int)
4) add(Component);
5) setVisible(boolean);
6) setLayout(Object);
Answer : 1,2,3
Which of the following layout managers honours the preferred size of a component:
(multiple)
1) CardLayout
2) FlowLayout
3) BorderLayout
4) GridLayout
Answer : 2
Given the following code what is the effect of a being 5:
public class Test {
public void add(int a) {
loop: for (int i = 1; i < 3; i++){
for (int j = 1; j < 3; j++) {
if (a == 5) {
break loop;
}
System.out.println(i * j);
}
}
}
}
1) Generate a runtime error
2) Throw an ArrayIndexOutOfBoundsException
3) Print the values: 1, 2, 2, 4
4) Produces no output
Answer : 4
What is the effect of issuing a wait() method on an object
1) If a notify() method has already been sent to that object then it has no effect
2) The object issuing the call to wait() will halt until another object sends a notify() or notifyAll() method
3) An exception will be raised
4) The object issuing the call to wait() will be automatically synchronized with any other objects using the receiving object.
Answer : 2
The layout of a container can be altered using which of the following methods:
(multiple)
1) setLayout(aLayoutManager);
2) addLayout(aLayoutManager);
3) layout(aLayoutManager);
4) setLayoutManager(aLayoutManager);
Answer : 1
Using a FlowLayout manager, which is the correct way to add elements to a container:
1) add(component);
2) add("Center", component);
3) add(x, y, component);
4) set(component);
Answer : 1
Given that a Button can generate an ActionEvent which listener would you expect to have to implement, in a class which would handle this event?
1) FocusListener
2) ComponentListener
3) WindowListener
4) ActionListener
5) ItemListener
Answer : 4
Which of the following, are valid return types, for listener methods:
1) boolean
2) the type of event handled
3) void
4) Component
Answer : 3
Assuming we have a class which implements the ActionListener interface, which method should be used to register this with a Button?
1) addListener(*);
2) addActionListener(*);
3) addButtonListener(*);
4) setListener(*);
Answer : 2
In order to cause the paint(Graphics) method to execute, which of the following is the most appropriate method to call:
1) paint()
2) repaint()
3) paint(Graphics)
4) update(Graphics)
5) None - you should never cause paint(Graphics) to execute
Answer : 2
Which of the following illustrates the correct way to pass a parameter into an applet:
1) tags applet code=Test.class age=33 width=100 height=100
2) tagsparam name=age value=33
3) tagsapplet code=Test.class name=age value=33 width=100 height=100
4) tagsapplet Test 33
Answer : 2
Which of the following correctly illustrate how an InputStreamReader can be created:
(multiple)
1) new InputStreamReader(new FileInputStream("data"));
2) new InputStreamReader(new FileReader("data"));
3) new InputStreamReader(new BufferedReader("data"));
4) new InputStreamReader("data");
5) new InputStreamReader(System.in);
Answer : 1,5
What is the permanent effect on the file system of writing data to a new FileWriter("report"), given the file report already exists?
1) The data is appended to the file
2) The file is replaced with a new file
3) An exception is raised as the file already exists
4) The data is written to random locations within the file
Answer : 2
What is the effect of adding the sixth element to a vector created in the following manner:
new Vector(5, 10);
1) An IndexOutOfBounds exception is raised.
2) The vector grows in size to a capacity of 10 elements
3) The vector grows in size to a capacity of 15 elements
4) Nothing, the vector will have grown when the fifth element was added
Answer : 3
What is the result of executing the following code when the value of x is 2:
switch (x) {
case 1:
System.out.println(1);
case 2:
case 3:
System.out.println(3);
case 4:
System.out.println(4);
}
1) Nothing is printed out
2) The value 3 is printed out
3) The values 3 and 4 are printed out
4) The values 1, 3 and 4 are printed out
Answer : 3
What is the result of compiling and running the Second class?
Consider the following example:
class First {
public First (String s) {
System.out.println(s);
}
}
public class Second extends First {
public static void main(String args []) {
new Second();
}
}
1) Nothing happens
2) A string is printed to the standard out
3) An instance of the class First is generated
4) An instance of the class Second is created
5) An exception is raised at runtime stating that there is no null parameter constructor in class First.
6) The class second will not compile as there is no null parameter constructor in the class First
Answer : 6
What is the result of executing the following fragment of code:
boolean flag = false;
if (flag = true) {
System.out.println("true");
} else {
System.out.println("false");
}
1) true is printed to standard out
2) false is printed to standard out
3) An exception is raised
4) Nothing happens
Answer : 1
Consider the following classes. What is the result of compiling and running this class?
public class Test {
public static void test() {
this.print();
}
public static void print() {
System.out.println("Test");
}
public static void main(String args []) {
test();
}
}
(multiple)
1) The string Test is printed to the standard out.
2) A runtime exception is raised stating that an object has not been created.
3) Nothing is printed to the standard output.
4) An exception is raised stating that the method test cannot be found.
5) An exception is raised stating that the variable this can only be used within an instance.
6) The class fails to compile stating that the variable this is undefined.
Answer : 6
Examine the following class definition:
public class Test {
public static void test() {
print();
}
public static void print() {
System.out.println("Test");
}
public void print() {
System.out.println("Another Test");
}
}
What is the result of compiling this class:
1) A successful compilation.
2) A warning stating that the class has no main method.
3) An error stating that there is a duplicated method.
4) An error stating that the method test() will call one or other of the print() methods.
Answer : 3
What is the result of compiling and executing the following Java class:
public class ThreadTest extends Thread {
public void run() {
System.out.println("In run");
suspend();
resume();
System.out.println("Leaving run");
}
public static void main(String args []) {
(new ThreadTest()).start();
}
}
1) Compilation will fail in the method main.
2) Compilation will fail in the method run.
3) A warning will be generated for method run.
4) The string "In run" will be printed to standard out.
5) Both strings will be printed to standard out.
6) Nothing will happen.
Answer : 4
Given the following sequence of Java statements, Which of the following options are true:
1. StringBuffer sb = new StringBuffer("abc");
2. String s = new String("abc");
3. sb.append("def");
4. s.append("def");
5. sb.insert(1, "zzz");
6. s.concat(sb);
7. s.trim();
(multiple)
1) The compiler would generate an error for line 1.
2) The compiler would generate an error for line 2.
3) The compiler would generate an error for line 3.
4) The compiler would generate an error for line 4.
5) The compiler would generate an error for line 5.
6) The compiler would generate an error for line 6.
7) The compiler would generate an error for line 7.
Answer : 4,6
What is the result of executing the following Java class:
import java.awt.*;
public class FrameTest extends Frame {
public FrameTest() {
add (new Button("First"));
add (new Button("Second"));
add (new Button("Third"));
pack();
setVisible(true);
}
public static void main(String args []) {
new FrameTest();
}
}
1) Nothing happens.
2) Three buttons are displayed across a window.
3) A runtime exception is generated (no layout manager specified).
4) Only the "first" button is displayed.
5) Only the "second" button is displayed.
6) Only the "third" button is displayed.
Answer : 6
Consider the following tags and attributes of tags, which can be used with the APPLET and APPLET(closing) tags?
1. CODEBASE
2. ALT
3. NAME
4. CLASS
5. JAVAC
6. HORIZONTALSPACE
7. VERTICALSPACE
8. WIDTH
9. PARAM
10. JAR
(multiple)
1) line 1, 2, 3
2) line 2, 5, 6, 7
3) line 3, 4, 5
4) line 8, 9, 10
5) line 8, 9
Answer : 1,5
Which of the following is a legal way to construct a RandomAccessFile:
1) RandomAccessFile("data", "r");
2) RandomAccessFile("r", "data");
3) RandomAccessFile("data", "read");
4) RandomAccessFile("read", "data");
Answer : 1
Carefully examine the following code, When will the string "Hi there" be printed?
public class StaticTest {
static {
System.out.println("Hi there");
}
public void print() {
System.out.println("Hello");
}
public static void main(String args []) {
StaticTest st1 = new StaticTest();
st1.print();
StaticTest st2 = new StaticTest();
st2.print();
}
}
1) Never.
2) Each time a new instance is created.
3) Once when the class is first loaded into the Java virtual machine.
4) Only when the static method is called explicitly.
Answer : 3
What is the result of the following program:
public class Test {
public static void main (String args []) {
boolean a = false;
if (a = true)
System.out.println("Hello");
else
System.out.println("Goodbye");
}
}
1) Program produces no output but terminates correctly.
2) Program does not terminate.
3) Prints out "Hello"
4) Prints out "Goodbye"
Answer : 3
Examine the following code, it includes an inner class, what is the result:
public final class Test4 {
class Inner {
void test() {
if (Test4.this.flag); {
sample();
}
}
}
private boolean flag = true;
public void sample() {
System.out.println("Sample");
}
public Test4() {
(new Inner()).test();
}
public static void main(String args []) {
new Test4();
}
}
1) Prints out "Sample"
2) Program produces no output but terminates correctly.
3) Program does not terminate.
4) The program will not compile
Answer : 1
Carefully examine the following class:
public class Test5 {
public static void main (String args []) {
/* This is the start of a comment
if (true) {
Test5 = new test5();
System.out.println("Done the test");
}
/* This is another comment */
System.out.println ("The end");
}
}
1) Prints out "Done the test" and nothing else.
2) Program produces no output but terminates correctly.
3) Program does not terminate.
4) The program will not compile.
5) The program generates a runtime exception.
6) The program prints out "The end" and nothing else.
7) The program prints out "Done the test" and "The end"
Answer : 6
What is the result of compiling and running the following applet:
import java.applet.Applet;
import java.awt.*;
public class Sample extends Applet {
private String text = "Hello World";
public void init() {
add(new Label(text));
}
public Sample (String string) {
text = string;
}
}
It is accessed form the following HTML page:
sshtmlss
sstitle Sample Applet closingtitle
ssbody "closing tags and opening tags "
ssapplet code="Sample.class" width=200 height=200> tagsssssapplet
body
sshtmlss
1) Prints "Hello World".
2) Generates a runtime error.
3) Does nothing.
4) Generates a compile time error.
Answer : 2
[we hav to write applets as such to prevent script file errors.]
What is the effect of compiling and (if possible) running this class:
public class Calc {
public static void main (String args []) {
int total = 0;
for (int i = 0, j = 10; total > 30; ++i, --j) {
System.out.println(" i = " + i + " : j = " + j);
total += (i + j);
}
System.out.println("Total " + total);
}
}
1) Produce a runtime error
2) Produce a compile time error
3) Print out "Total 0"
4) Generate the following as output:
i = 0 : j = 10
i = 1 : j = 9
i = 2 : j = 8
Total 30
Answer : 3
What is meant by Controls and what are different types of controls?
Ans : Controls are componenets that allow a user to interact with your application.
The AWT supports the following types of controls:
Labels
Push buttons
Check boxes
Choice lists
Lists
Scroll bars
Text components
These controls are subclasses of Component.
You want to construct a text area that is 80 character-widths wide and 10 character-heights tall. What code do you use?
new TextArea(80, 10)
new TextArea(10, 80)
Ans: b.
A text field has a variable-width font. It is constructed by calling new
TextField("iiiii"). What happens if you change the contents of the text field to
"wwwww"? (Bear in mind that is one of the narrowest characters, and w is one of the widest.)
The text field becomes wider.
The text field becomes narrower.
The text field stays the same width; to see the entire contents you will have to scroll by using the ß and à keys.
The text field stays the same width; to see the entire contents you will have to scroll by using the text field’s horizontal scroll bar.
Ans : c.
The CheckboxGroup class is a subclass of the Component class.
True
False
Ans : b.
5) What are the immediate super classes of the following classes?
a) Container class
b) MenuComponent class
c) Dialog class
d) Applet class
e) Menu class
Ans : a) Container - Component
b) MenuComponent - Object
c) Dialog - Window
d) Applet - Panel
e) Menu - MenuItem
6) What are the SubClass of Textcomponent Class?
Ans : TextField and TextArea
7) Which method of the component class is used to set the position and the size of a component?
Ans : setBounds()
8) Which TextComponent method is used to set a TextComponent to the read-only state?
Ans : setEditable()
9) How can the Checkbox class be used to create a radio button?
Ans : By associating Checkbox objects with a CheckboxGroup.
10) What Checkbox method allows you to tell if a Checkbox is checked?
Ans : getState()
11) Which Component method is used to access a component's immediate Container?
getVisible()
getImmediate
getParent()
getContainer
Ans : c.
12) What methods are used to get and set the text label displayed by a Button object?
Ans : getLabel( ) and setLabel( )
13) What is the difference between a Choice and a List?
Ans : A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice.
A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.
14) Which Container method is used to cause a container to be laid out and redisplayed?
Ans : validate( )
15) What is the difference between a Scollbar and a Scrollpane?
Ans : A Scrollbar is a Component, but not a Container.
A Scrollpane is a Container and handles its own events and performs its own
scrolling.
16) Which Component subclass is used for drawing and painting?
Ans : Canvas.
17) Which of the following are direct or indirect subclasses of Component?
Button
Label
CheckboxMenuItem
Toolbar
Frame
Ans : a, b and e.
18) Which of the following are direct or indirect subclasses of Container?
Frame
TextArea
MenuBar
FileDialog
Applet
Ans : a,d and e.
19) Which method is used to set the text of a Label object?
setText( )
setLabel( )
setTextLabel( )
setLabelText( )
Ans : a.
20) Which constructor creates a TextArea with 10 rows and 20 columns?
new TextArea(10, 20)
new TextArea(20, 10)
new TextArea(new Rows(10), new columns(20))
new TextArea(200)
Ans : a.
(Usage is TextArea(rows, columns)
21) Which of the following creates a List with 5 visible items and multiple selection enabled?
new List(5, true)
new List(true, 5)
new List(5, false)
new List(false,5)
Ans : a.
[Usage is List(rows, multipleMode)]
22) Which are true about the Container class?
The validate( ) method is used to cause a Container to be laid out and redisplayed.
The add( ) method is used to add a Component to a Container.
The getBorder( ) method returns information about a Container’s insets.
The getComponent( ) method is used to access a Component that is contained in a Container.
Ans : a, b and d.
23) Suppose a Panel is added to a Frame and a Button is added to the Panel. If the Frame’s font is set to 12-point TimesRoman, the Panel’s font is set to 10-point TimesRoman, and the Button’s font is not set, what font will be used to dispaly the Button’s label?
12-point TimesRoman
11-point TimesRoman
10-point TimesRoman
9-point TimesRoman
Ans : c.
A Frame’s background color is set to Color.Yellow, and a Button’s background color is to Color.Blue. Suppose the Button is added to a Panel, which is added to the Frame. What background color will be used with the Panel?
Color.Yellow
Color.Blue
Color.Green
Color.White
Ans : a.
25) Which method will cause a Frame to be displayed?
show( )
setVisible( )
display( )
displayFrame( )
Ans : a and b.
26) All the componenet classes and container classes are derived from _________
class.
Ans : Object.
27) Which method of the container class can be used to add components to a Panel.
Ans : add ( ) method.
28) What are the subclasses of the Container class?
Ans : The Container class has three major subclasses. They are :
Window
Panel
ScrollPane
29) The Choice component allows multiple selection.
True.
False.
Ans : b.
30) The List component does not generate any events.
True.
False.
Ans : b.
31) Which components are used to get text input from the user.
Ans : TextField and TextArea.
32) Which object is needed to group Checkboxes to make them exclusive?
Ans : CheckboxGroup.
33) Which of the following components allow multiple selections?
Non-exclusive Checkboxes.
Radio buttons.
Choice.
List.
Ans : a and d.
34) What are the types of Checkboxes and what is the difference between them?
Ans : Java supports two types of Checkboxes. They are : Exclusive and Non-exclusive.
In case of exclusive Checkboxes, only one among a group of items can be selected at a time. I f an item from the group is selected, the checkbox currently checked is deselected and the new selection is highlighted. The exclusive Checkboxes are also called as Radio buttons.
The non-exclusive checkboxes are not grouped together and each one can be selected independent of the other.
35) What is a Layout Manager and what are the different Layout Managers available in java.awt and what is the default Layout manager for the panel and the panel subclasses?
Ans: A layout Manager is an object that is used to organize components in a container.
The different layouts available in java.awt are :
FlowLayout, BorderLayout, CardLayout, GridLayout and GridBag Layout.
The default Layout Manager of Panal and Panal sub classes is FlowLayout".
36) Can I exert control over the size and placement of components in my interface?
Ans : Yes.
myPanal.setLayout(null);
myPanal.setbounds(20,20,200,200);
37) Can I add the same component to more than one container?
Ans : No. Adding a component to a container automatically removes it from any previous parent(container).
38) How do I specify where a window is to be placed?
Ans : Use setBounds, setSize, or setLocation methods to implement this.
setBounds(int x, int y, int width, int height)
setBounds(Rectangle r)
setSize(int width, int height)
setSize(Dimension d)
setLocation(int x, int y)
setLocation(Point p)
39) How can we create a borderless window?
Ans : Create an instance of the Window class, give it a size, and show it on the screen.
eg. Frame aFrame = ......
Window aWindow = new Window(aFrame);
aWindow.setLayout(new FlowLayout());
aWindow.add(new Button("Press Me"));
aWindow.getBounds(50,50,200,200);
aWindow.show();
40) Can I create a non-resizable windows? If so, how?
Ans: Yes. By using setResizable() method in class Frame.
41) What is the default Layout Manager for the Window and Window subclasses (Frame,Dialog)?
Ans : BorderLayout().
42) How are the elements of different layouts organized?
Ans : FlowLayout : The elements of a FlowLayout are organized in a top to bottom, left to right fashion.
BorderLayout : The elements of a BorderLayout are organized at the
borders (North, South, East and West) and the center of a
container.
CardLayout : The elements of a CardLayout are stacked, one on top of the other, like a deck of cards.
GridLayout : The elements of a GridLayout are of equal size and are laid out using the square of a grid.
GridBagLayout : The elements of a GridBagLayout are organized according to a grid.However, the elements are of different sizes and may occupy
more than one row or column of the grid. In addition, the rows and columns may have different sizes.
43) Which containers use a BorderLayout as their default layout?
Ans : The Window, Frame and Dialog classes use a BorderLayout as their default layout.
44) Which containers use a FlowLayout as their default layout?
Ans : The Panel and the Applet classes use the FlowLayout as their default layout.
45) What is the preferred size of a component?
Ans : The preferred size of a component size that will allow the component to display normally.
46) Which method is method to set the layout of a container?
startLayout( )
initLayout( )
layoutContainer( )
setLayout( )
Ans : d.
47) Which method returns the preferred size of a component?
getPreferredSize( )
getPreferred( )
getRequiredSize( )
getLayout( )
Ans : a.
48) Which layout should you use to organize the components of a container in a
tabular form?
CardLayout
BorederLayout
FlowLayout
GridLayout
Ans : d.
An application has a frame that uses a Border layout manager. Why is it probably not a good idea to put a vertical scroll bar at North in the frame?
The scroll bar’s height would be its preferred height, which is not likely to be enough.
The scroll bar’s width would be the entire width of the frame, which would be much wider than necessary.
Both a and b.
Neither a nor b. There is no problem with the layout as described.
Ans : c.
What is the default layouts for a applet, a frame and a panel?
Ans : For an applet and a panel, Flow layout is the default layout, whereas Border layout is default layout for a frame.
If a frame uses a Grid layout manager and does not contain any panels, then all the components within the frame are the same width and height.
True
False.
Ans : a.
If a frame uses its default layout manager and does not contain any panels, then all the components within the frame are the same width and height.
True
False.
Ans : b.
With a Border layout manager, the component at Center gets all the space that is left over, after the components at North and South have been considered.
True
False
Ans : b.
An Applet has its Layout Manager set to the default of FlowLayout. What code would be the correct to change to another Layout Manager?
setLayoutManager(new GridLayout());
setLayout(new GridLayout(2,2));
c) setGridLayout(2,2,))
d setBorderLayout();
Ans : b.
55) How do you indicate where a component will be positioned using Flowlayout?
a) North, South,East,West
b) Assign a row/column grid reference
c) Pass a X/Y percentage parameter to the add method
d) Do nothing, the FlowLayout will position the component
Ans :d.
56) How do you change the current layout manager for a container?
a) Use the setLayout method
b) Once created you cannot change the current layout manager of a component
c) Use the setLayoutManager method
d) Use the updateLayout method
Ans :a.
57)When using the GridBagLayout manager, each new component requires a new instance of the GridBagConstraints class. Is this statement true or false?
a) true
b) false
Ans : b.
58) Which of the following statements are true?
a)The default layout manager for an Applet is FlowLayout
b) The default layout manager for an application is FlowLayout
c) A layout manager must be assigned to an Applet before the setSize method is called
d) The FlowLayout manager attempts to honor the preferred size of any components
Ans : a and d.
59) Which method does display the messages whenever there is an item selection or deselection of the CheckboxMenuItem menu?
Ans : itemStateChanged method.
60) Which is a dual state menu item?
Ans : CheckboxMenuItem.
61) Which method can be used to enable/diable a checkbox menu item?
Ans : setState(boolean).
Which of the following may a menu contain?
A separator
A check box
A menu
A button
A panel
Ans : a and c.
Which of the following may contain a menu bar?
A panel
A frame
An applet
A menu bar
A menu
Ans : b
64) What is the difference between a MenuItem and a CheckboxMenuItem?
Ans : The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked.
65) Which of the following are true?
A Dialog can have a MenuBar.
MenuItem extends Menu.
A MenuItem can be added to a Menu.
A Menu can be added to a Menu.
Ans : c and d.
Which colour is used to indicate instance methods in the standard "javadoc" format documentation:
1) blue
2) red
3) purple
4) orange
Answer : 2
Explain In JDK 1.1 the variabels, methods and constructors are colour coded to simplifytheir identification.
endExplain
What is the correct ordering for the import, class and package declarations when found in a single file?
1) package, import, class
2) class, import, package
3) import, package, class
4) package, class, import
Answer : 1
Which methods can be legally applied to a string object?
(Multiple)
1) equals(String)
2) equals(Object)
3) trim()
4) round()
5) toString()
Answer : 1,2,3,5
What is the parameter specification for the public static void main method?
(multiple)
1) String args []
2) String [] args
3) Strings args []
4) String args
Answer : 1,2
What does the zeroth element of the string array passed to the public static void main method contain?
(multiple)
1) The name of the program
2) The number of arguments
3) The first argument if one is present
Answer : 3
Which of the following are Java keywords?
(multiple)
1) goto
2) malloc
3) extends
4) FALSE
Answer : 3
What will be the result of compiling the following code:
public class Test {
public static void main (String args []) {
int age;
age = age + 1;
System.out.println("The age is " + age);
}
}
1) Compiles and runs with no output
2) Compiles and runs printing out The age is 1
3) Compiles but generates a runtime error
4) Does not compile
5) Compiles but generates a compile time error
Answer : 4
Which of these is the correct format to use to create the literal char value a?
(multiple)
1) 'a'
2) "a"
3) new Character(a)
4) \000a
Answer : 1
What is the legal range of a byte integral type?
1) 0 - 65, 535
2) (-128) - 127
3) (-32,768) - 32,767
4) (-256) - 255
Answer : 2
Which of the following is illegal:
1) int i = 32;
2) float f = 45.0;
3) double d = 45.0;
Answer 2
What will be the result of compiling the following code:
public class Test {
static int age;
public static void main (String args []) {
age = age + 1;
System.out.println("The age is " + age);
}
}
1) Compiles and runs with no output
2) Compiles and runs printing out The age is 1
3) Compiles but generates a runtime error
4) Does not compile
5) Compiles but generates a compile time error
Answer : 2
Which of the following are correct?
(multiple)
1) 128 >> 1 gives 64
2) 128 >>> 1 gives 64
3) 128 >> 1 gives -64
4) 128 >>> 1 gives -64
Answer : 1
Which of the following return true?
(multiple)
1) "john" == new String("john")
2) "john".equals("john")
3) "john" = "john"
4) "john".equals(new Button("john"))
Answer : 2
Which of the following do not lead to a runtime error?
(multiple)
1) "john" + " was " + " here"
2) "john" + 3
3) 3 + 5
4) 5 + 5.5
answer 1,2,3,4
Which of the following are so called "short circuit" logical operators?
(multiple)
1) &
2) ||
3) &&
4) |
Answer : 2,3
Which of the following are acceptable?
(multiple)
1) Object o = new Button("A");
2) Boolean flag = true;
3) Panel p = new Frame();
4) Frame f = new Panel();
5) Panel p = new Applet();
Answer : 1,5
What is the result of compiling and running the following code:
public class Test {
static int total = 10;
public static void main (String args []) {
new Test();
}
public Test () {
System.out.println("In test");
System.out.println(this);
int temp = this.total;
if (temp > 5) {
System.out.println(temp);
}
}
}
(multiple)
1) The class will not compile
2) The compiler reports and error at line 2
3) The compiler reports an error at line 9
4) The value 10 is one of the elements printed to the standard output
5) The class compiles but generates a runtime error
Answer : 4
Which of the following is correct:
1) String temp [] = new String {"j" "a" "z"};
2) String temp [] = { "j " " b" "c"};
3) String temp = {"a", "b", "c"};
4) String temp [] = {"a", "b", "c"};
Answer 4
What is the correct declaration of an abstract method that is intended to be public:
1) public abstract void add();
2) public abstract void add() {}
3) public abstract add();
4) public virtual add();
Answer : 1
Under what situations do you obtain a default constructor?
1) When you define any class
2) When the class has no other constructors
3) When you define at least one constructor
Answer : 2
Which of the following can be used to define a constructor for this class, given the following code:
public class Test {
...
}
1) public void Test() {...}
2) public Test() {...}
3) public static Test() {...}
4) public static void Test() {...}
Answer : 2
Which of the following are acceptable to the Java compiler:
(multiple)
1) if (2 == 3) System.out.println("Hi");
2) if (2 = 3) System.out.println("Hi");
3) if (true) System.out.println("Hi");
4) if (2 != 3) System.out.println("Hi");
5) if (aString.equals("hello")) System.out.println("Hi");
Answer : 1,3,4,5
Assuming a method contains code which may raise an Exception (but not a RuntimeException), what is the correct way for a method to indicate that it expects the caller to handle that exception:
1) throw Exception
2) throws Exception
3) new Exception
4) Don't need to specify anything
Answer : 2
What is the result of executing the following code, using the parameters 4 and 0:
public void divide(int a, int b) {
try {
int c = a / b;
} catch (Exception e) {
System.out.print("Exception ");
} finally {
System.out.println("Finally");
}
1) Prints out: Exception Finally
2) Prints out: Finally
3) Prints out: Exception
4) No output
Answer : 1
Which of the following is a legal return type of a method overloading the following method:
public void add(int a) {...}
1) void
2) int
3) Can be anything
Answer : 3
Which of the following statements is correct for a method which is overriding the following method:
public void add(int a) {...}
1) the overriding method must return void
2) the overriding method must return int
3) the overriding method can return whatever it likes
Answer : 1
Given the following classes defined in separate files, what will be the effect of compiling and running this class Test?
class Vehicle {
public void drive() {
System.out.println("Vehicle: drive");
}
}
class Car extends Vehicle {
public void drive() {
System.out.println("Car: drive");
}
}
public class Test {
public static void main (String args []) {
Vehicle v;
Car c;
v = new Vehicle();
c = new Car();
v.drive();
c.drive();
v = c;
v.drive();
}
}
1) Generates a Compiler error on the statement v= c;
2) Generates runtime error on the statement v= c;
3) Prints out:
Vehicle: drive
Car: drive
Car: drive
4) Prints out:
Vehicle: drive
Car: drive
Vehicle: drive
Answer : 3
Where in a constructor, can you place a call to a constructor defined in the super class?
1) Anywhere
2) The first statement in the constructor
3) The last statement in the constructor
4) You can't call super in a constructor
Answer : 2
Which variables can an inner class access from the class which encapsulates it?
(multiple)
1) All static variables
2) All final variables
3) All instance variables
4) Only final instance variables
5) Only final static variables
Answer : 1,2,3
What class must an inner class extend:
1) The top level class
2) The Object class
3) Any class or interface
4) It must extend an interface
Answer 3
In the following code, which is the earliest statement, where the object originally held in e, may be garbage collected:
1. public class Test {
2. public static void main (String args []) {
3. Employee e = new Employee("Bob", 48);
4. e.calculatePay();
5. System.out.println(e.printDetails());
6. e = null;
7. e = new Employee("Denise", 36);
8. e.calculatePay();
9. System.out.println(e.printDetails());
10. }
11. }
1) Line 10
2) Line 11
3) Line 7
4) Line 8
5) Never
Answer : 3
What is the name of the interface that can be used to define a class that can execute within its own thread?
1) Runnable
2) Run
3) Threadable
4) Thread
5) Executable
Answer : 1
What is the name of the method used to schedule a thread for execution?
1) init();
2) start();
3) run();
4) resume();
5) sleep();
Answer : 2
Which methods may cause a thread to stop executing?
(multiple)
1) sleep();
2) stop();
3) yield();
4) wait();
5) notify();
6) notifyAll()
7) synchronized()
Answer : 1,2,3,4
Which of the following would create a text field able to display 10 characters (assuming a fixed size font) displaying the initial string "hello":
1) new TextField("hello", 10);
2) new TextField("hello");
3) new textField(10);
4) new TextField();
Answer : 1
Which of the following methods are defined on the Graphics class:
(multiple)
1) drawLine(int, int, int, int)
2) drawImage(Image, int, int, ImageObserver)
3) drawString(String, int, int)
4) add(Component);
5) setVisible(boolean);
6) setLayout(Object);
Answer : 1,2,3
Which of the following layout managers honours the preferred size of a component:
(multiple)
1) CardLayout
2) FlowLayout
3) BorderLayout
4) GridLayout
Answer : 2
Given the following code what is the effect of a being 5:
public class Test {
public void add(int a) {
loop: for (int i = 1; i < 3; i++){
for (int j = 1; j < 3; j++) {
if (a == 5) {
break loop;
}
System.out.println(i * j);
}
}
}
}
1) Generate a runtime error
2) Throw an ArrayIndexOutOfBoundsException
3) Print the values: 1, 2, 2, 4
4) Produces no output
Answer : 4
What is the effect of issuing a wait() method on an object
1) If a notify() method has already been sent to that object then it has no effect
2) The object issuing the call to wait() will halt until another object sends a notify() or notifyAll() method
3) An exception will be raised
4) The object issuing the call to wait() will be automatically synchronized with any other objects using the receiving object.
Answer : 2
The layout of a container can be altered using which of the following methods:
(multiple)
1) setLayout(aLayoutManager);
2) addLayout(aLayoutManager);
3) layout(aLayoutManager);
4) setLayoutManager(aLayoutManager);
Answer : 1
Using a FlowLayout manager, which is the correct way to add elements to a container:
1) add(component);
2) add("Center", component);
3) add(x, y, component);
4) set(component);
Answer : 1
Given that a Button can generate an ActionEvent which listener would you expect to have to implement, in a class which would handle this event?
1) FocusListener
2) ComponentListener
3) WindowListener
4) ActionListener
5) ItemListener
Answer : 4
Which of the following, are valid return types, for listener methods:
1) boolean
2) the type of event handled
3) void
4) Component
Answer : 3
Assuming we have a class which implements the ActionListener interface, which method should be used to register this with a Button?
1) addListener(*);
2) addActionListener(*);
3) addButtonListener(*);
4) setListener(*);
Answer : 2
In order to cause the paint(Graphics) method to execute, which of the following is the most appropriate method to call:
1) paint()
2) repaint()
3) paint(Graphics)
4) update(Graphics)
5) None - you should never cause paint(Graphics) to execute
Answer : 2
Which of the following illustrates the correct way to pass a parameter into an applet:
1) tags applet code=Test.class age=33 width=100 height=100
2) tagsparam name=age value=33
3) tagsapplet code=Test.class name=age value=33 width=100 height=100
4) tagsapplet Test 33
Answer : 2
Which of the following correctly illustrate how an InputStreamReader can be created:
(multiple)
1) new InputStreamReader(new FileInputStream("data"));
2) new InputStreamReader(new FileReader("data"));
3) new InputStreamReader(new BufferedReader("data"));
4) new InputStreamReader("data");
5) new InputStreamReader(System.in);
Answer : 1,5
What is the permanent effect on the file system of writing data to a new FileWriter("report"), given the file report already exists?
1) The data is appended to the file
2) The file is replaced with a new file
3) An exception is raised as the file already exists
4) The data is written to random locations within the file
Answer : 2
What is the effect of adding the sixth element to a vector created in the following manner:
new Vector(5, 10);
1) An IndexOutOfBounds exception is raised.
2) The vector grows in size to a capacity of 10 elements
3) The vector grows in size to a capacity of 15 elements
4) Nothing, the vector will have grown when the fifth element was added
Answer : 3
What is the result of executing the following code when the value of x is 2:
switch (x) {
case 1:
System.out.println(1);
case 2:
case 3:
System.out.println(3);
case 4:
System.out.println(4);
}
1) Nothing is printed out
2) The value 3 is printed out
3) The values 3 and 4 are printed out
4) The values 1, 3 and 4 are printed out
Answer : 3
What is the result of compiling and running the Second class?
Consider the following example:
class First {
public First (String s) {
System.out.println(s);
}
}
public class Second extends First {
public static void main(String args []) {
new Second();
}
}
1) Nothing happens
2) A string is printed to the standard out
3) An instance of the class First is generated
4) An instance of the class Second is created
5) An exception is raised at runtime stating that there is no null parameter constructor in class First.
6) The class second will not compile as there is no null parameter constructor in the class First
Answer : 6
What is the result of executing the following fragment of code:
boolean flag = false;
if (flag = true) {
System.out.println("true");
} else {
System.out.println("false");
}
1) true is printed to standard out
2) false is printed to standard out
3) An exception is raised
4) Nothing happens
Answer : 1
Consider the following classes. What is the result of compiling and running this class?
public class Test {
public static void test() {
this.print();
}
public static void print() {
System.out.println("Test");
}
public static void main(String args []) {
test();
}
}
(multiple)
1) The string Test is printed to the standard out.
2) A runtime exception is raised stating that an object has not been created.
3) Nothing is printed to the standard output.
4) An exception is raised stating that the method test cannot be found.
5) An exception is raised stating that the variable this can only be used within an instance.
6) The class fails to compile stating that the variable this is undefined.
Answer : 6
Examine the following class definition:
public class Test {
public static void test() {
print();
}
public static void print() {
System.out.println("Test");
}
public void print() {
System.out.println("Another Test");
}
}
What is the result of compiling this class:
1) A successful compilation.
2) A warning stating that the class has no main method.
3) An error stating that there is a duplicated method.
4) An error stating that the method test() will call one or other of the print() methods.
Answer : 3
What is the result of compiling and executing the following Java class:
public class ThreadTest extends Thread {
public void run() {
System.out.println("In run");
suspend();
resume();
System.out.println("Leaving run");
}
public static void main(String args []) {
(new ThreadTest()).start();
}
}
1) Compilation will fail in the method main.
2) Compilation will fail in the method run.
3) A warning will be generated for method run.
4) The string "In run" will be printed to standard out.
5) Both strings will be printed to standard out.
6) Nothing will happen.
Answer : 4
Given the following sequence of Java statements, Which of the following options are true:
1. StringBuffer sb = new StringBuffer("abc");
2. String s = new String("abc");
3. sb.append("def");
4. s.append("def");
5. sb.insert(1, "zzz");
6. s.concat(sb);
7. s.trim();
(multiple)
1) The compiler would generate an error for line 1.
2) The compiler would generate an error for line 2.
3) The compiler would generate an error for line 3.
4) The compiler would generate an error for line 4.
5) The compiler would generate an error for line 5.
6) The compiler would generate an error for line 6.
7) The compiler would generate an error for line 7.
Answer : 4,6
What is the result of executing the following Java class:
import java.awt.*;
public class FrameTest extends Frame {
public FrameTest() {
add (new Button("First"));
add (new Button("Second"));
add (new Button("Third"));
pack();
setVisible(true);
}
public static void main(String args []) {
new FrameTest();
}
}
1) Nothing happens.
2) Three buttons are displayed across a window.
3) A runtime exception is generated (no layout manager specified).
4) Only the "first" button is displayed.
5) Only the "second" button is displayed.
6) Only the "third" button is displayed.
Answer : 6
Consider the following tags and attributes of tags, which can be used with the APPLET and APPLET(closing) tags?
1. CODEBASE
2. ALT
3. NAME
4. CLASS
5. JAVAC
6. HORIZONTALSPACE
7. VERTICALSPACE
8. WIDTH
9. PARAM
10. JAR
(multiple)
1) line 1, 2, 3
2) line 2, 5, 6, 7
3) line 3, 4, 5
4) line 8, 9, 10
5) line 8, 9
Answer : 1,5
Which of the following is a legal way to construct a RandomAccessFile:
1) RandomAccessFile("data", "r");
2) RandomAccessFile("r", "data");
3) RandomAccessFile("data", "read");
4) RandomAccessFile("read", "data");
Answer : 1
Carefully examine the following code, When will the string "Hi there" be printed?
public class StaticTest {
static {
System.out.println("Hi there");
}
public void print() {
System.out.println("Hello");
}
public static void main(String args []) {
StaticTest st1 = new StaticTest();
st1.print();
StaticTest st2 = new StaticTest();
st2.print();
}
}
1) Never.
2) Each time a new instance is created.
3) Once when the class is first loaded into the Java virtual machine.
4) Only when the static method is called explicitly.
Answer : 3
What is the result of the following program:
public class Test {
public static void main (String args []) {
boolean a = false;
if (a = true)
System.out.println("Hello");
else
System.out.println("Goodbye");
}
}
1) Program produces no output but terminates correctly.
2) Program does not terminate.
3) Prints out "Hello"
4) Prints out "Goodbye"
Answer : 3
Examine the following code, it includes an inner class, what is the result:
public final class Test4 {
class Inner {
void test() {
if (Test4.this.flag); {
sample();
}
}
}
private boolean flag = true;
public void sample() {
System.out.println("Sample");
}
public Test4() {
(new Inner()).test();
}
public static void main(String args []) {
new Test4();
}
}
1) Prints out "Sample"
2) Program produces no output but terminates correctly.
3) Program does not terminate.
4) The program will not compile
Answer : 1
Carefully examine the following class:
public class Test5 {
public static void main (String args []) {
/* This is the start of a comment
if (true) {
Test5 = new test5();
System.out.println("Done the test");
}
/* This is another comment */
System.out.println ("The end");
}
}
1) Prints out "Done the test" and nothing else.
2) Program produces no output but terminates correctly.
3) Program does not terminate.
4) The program will not compile.
5) The program generates a runtime exception.
6) The program prints out "The end" and nothing else.
7) The program prints out "Done the test" and "The end"
Answer : 6
What is the result of compiling and running the following applet:
import java.applet.Applet;
import java.awt.*;
public class Sample extends Applet {
private String text = "Hello World";
public void init() {
add(new Label(text));
}
public Sample (String string) {
text = string;
}
}
It is accessed form the following HTML page:
sshtmlss
sstitle Sample Applet closingtitle
ssbody "closing tags and opening tags "
ssapplet code="Sample.class" width=200 height=200> tagsssssapplet
body
sshtmlss
1) Prints "Hello World".
2) Generates a runtime error.
3) Does nothing.
4) Generates a compile time error.
Answer : 2
[we hav to write applets as such to prevent script file errors.]
What is the effect of compiling and (if possible) running this class:
public class Calc {
public static void main (String args []) {
int total = 0;
for (int i = 0, j = 10; total > 30; ++i, --j) {
System.out.println(" i = " + i + " : j = " + j);
total += (i + j);
}
System.out.println("Total " + total);
}
}
1) Produce a runtime error
2) Produce a compile time error
3) Print out "Total 0"
4) Generate the following as output:
i = 0 : j = 10
i = 1 : j = 9
i = 2 : j = 8
Total 30
Answer : 3
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