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What event results from the clicking of a button
The ActionEvent event is generated as the result of the clicking of a button.
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What is the difference between the Reader/Writer class hierarchy and theInputStream/OutputStream class hierarchy
The Reader/Writer class hierarchy is character-oriented, and theInputStream/OutputStream class hierarchy is byte-oriented.
Sandhya.Kishan
- May 7th, 2012
Character-oriented hierarchy is supported by reader/writer class where as byte-oriented hierarchy is supported by
InputStream/OutputStream class. -
Which Component subclass is used for drawing and painting
Canvas
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What value does read() return when it has reached the end of a file
The read() method returns -1 when it has reached the end of a file.
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What value does readLine() return when it has reached the end of a file
The readLine() method returns null when it has reached the end of a file.
Sandhya.Kishan
- May 4th, 2012
The readline() method returns null when it reaches the end of the line.
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What method must be implemented by all threads
All tasks must implement the run() method, whether they are a subclass of Thread orimplement the Runnable interface.
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Can an abstract class be final
An abstract class may not be declared as final.
Sandhya.Kishan
- May 4th, 2012
Abstract classes are the classes which can be subclassed but once if a class is declared as final we cant sub class
that so that as abstract class can never be final. -
What interface is extended by AWT event listeners
All AWT event listeners extend the java.util.EventListener interface.
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What is a compilation unit
A compilation unit is a Java source code file.
Sandhya.Kishan
- May 3rd, 2012
The source code for a Java class is called a compilation unit. Normally a compilation unit contains a single class definition and it is named for that class.
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What is a layout manager
A layout manager is an object that is used to organize components in a container.
Sandhya.Kishan
- May 3rd, 2012
The arrangement of the components in the container is determined by the layout manager.
Example:When we add a component to an applet or a container, the container uses its layout manager to decide where to put the component. -
When is an object subject to garbage collection
An object is subject to garbage collection when it becomes unreachable to the program inwhich it is used.
Sandhya.Kishan
- May 3rd, 2012
When an object becomes unreachable to any of the code then that object becomes eligible for garbage collection.
Once an object is garbage collected, It can no longer become reachable again. -
Which java.util classes and interfaces support event handling
The EventObject class and the EventListener interface support event processing.
Nandhitha S
- May 3rd, 2012
Import java.awt.event.*;
Sandhya.Kishan
- Apr 28th, 2012
EventObject class and the EventListener interface support event handling in Java.Util class.
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To what value is a variable of the boolean type automatically initialized
The default value of the boolean type is false.
Sandhya.Kishan
- May 3rd, 2012
Boolean type variable is always automatically initialized to false value.
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What interface must an object implement before it can be written to astream as an object
An object must implement the Serializable or Externalizable interface before it can bewritten to a stream as an object.
Sandhya.Kishan
- May 3rd, 2012
An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.
As it is a mechanism with which we can save the state of an object by converting it to a byte stream. -
What is the immediate superclass of the Dialog class
Window
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Name three Component subclasses that support painting
The Canvas, Frame, Panel, and Applet classes support painting.
Sandhya.Kishan
- Apr 28th, 2012
Canvas class, frame class and applet class are the subclasses that support painting.
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Why do threads block on I/O
Threads block on i/o (that is enters the waiting state) so that other threads may executewhile the i/oOperation is performed.
Sandhya.Kishan
- Apr 24th, 2012
While performing the i/o operation a thread is blocked and there by it allows the next thread in the queue to complete its execution.
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Which containers use a border Layout as their default layout
The window, Frame and Dialog classes use a border layout as their default layout.
Sandhya.Kishan
- Apr 24th, 2012
The border layout is used as default layout in Window, Frame and Dialog class containers.
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What is clipping
Clipping is the process of confining paint operations to a limited area or shape.
Sandhya.Kishan
- Apr 24th, 2012
Confining the areas of paint to a limited shape and size is known as clipping.
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Which containers may have a MenuBar
Frame
Java Interview Questions
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