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DataType Byte Values
What are the byte values of datatypes?
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Inherit Private/Protected Class
Can a private/protected class be inherited? Explain
Sandhya.Kishan
- Aug 1st, 2012
Yes, but they are not accessible. Although they are not visible or accessible via the class interface, they are inherited.
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Read Input at Run Time
What are the different ways to read input from keyboard at run time?
Sandhya.Kishan
- Aug 1st, 2012
By using scanner class we can input data from the keyboard.By declaring the Scanner classs input as System.in, it pulls data from the keyboard (default system input).
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What restrictions are placed on the values of each case of a switch statement
During compilation, the values of each case of a switch statement must evaluate to avalue that can bepromoted to an int value.
Sandhya.Kishan
- Jul 31st, 2012
1.The compiler does not initialize auto and register variables at the beginning of a switch body where as we can put data definitions at the beginning of the switch body.
2.We cannot use a switch statement to jump over initializations. -
What is the difference between the paint() and repaint() methods
The paint() method supports painting via a Graphics object. The repaint() method is usedto cause paint() tobe invoked by the AWT painting thread.
Sandhya.Kishan
- Jul 31st, 2012
Whenever the window needs to be refreshed the paint() method is called automatically.The user does not specify the paint(). The user specifies the repaint() in order to obtain a rendering.repaint() i...
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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 theRunnable interface.
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What is the difference between a public and a non-public class
A public class may be accessed outside of its package. A non-public class may not beaccessed outside ofits package.
Sandhya.Kishan
- Jul 31st, 2012
We can access a public class out of its package where as the access outside the package is not possible with a non public class.
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What an I/O filter
An I/O filter is an object that reads from one stream and writes to another, usuallyaltering the data in someway as it is passed from one stream to another.
Sandhya.Kishan
- Jul 31st, 2012
To read from one stream and then to write on other stream we use i/o filter.
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When is the finally clause of a try-catch-finally statement executed
The finally clause of the try-catch-finally statement is always executed unless the threadof executionterminates or an exception occurs within the execution of the finally clause.
Sandhya.Kishan
- Jul 31st, 2012
The finally clause of a try-catch-finally statement executed when the thread of execution terminates or an exception occurs within the execution of the finally clause.
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What is the relationship between a method's throws clause and the exceptionsthat can bethrown during the method's execution
A method's throws clause must declare any checked exceptions that are not caught withinthe body of themethod.
Sandhya.Kishan
- Jul 31st, 2012
Any checked exceptions that are not caught within the body of the method must declare in a methods throws clause.
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What is the Collection interface
The Collection interface provides support for the implementation of a mathematical bag -an unorderedcollection of objects that may contain duplicates.
Sandhya.Kishan
- Jul 31st, 2012
The Collection interface is used to pass around collections of objects where maximum generality is desired.It is one of the root interfaces of the Java collection classes.It provides support for the implementation of an unordered collection of objects that may contain duplicates.
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What is the relationship between clipping and repainting
When a window is repainted by the AWT painting thread, it sets the clipping regions tothe area of thewindow that requires repainting.
Sandhya.Kishan
- Jul 31st, 2012
Clipping regions are set to the repinted window on the area that requires repainting.When a window is repainted by the AWT painting thread, it sets the clipping regions tothe area of the window that requires repainting.
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Q: Why are Java ARchive (JAR) files important?
JAR files bundle .class files and optimize applet downloads.
Sandhya.Kishan
- Jul 30th, 2012
Jar files are important as it contains the class, image, and sound files for a Java application or applet gathered into a single file and possibly compressed. When a programmer gets a Java program dev...
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What happens when a thread cannot acquire a lock on an object
If a thread attempts to execute a synchronized method or synchronized statement and isunable to acquirean object's lock, it enters the waiting state until the lock becomes available.
Sandhya.Kishan
- Jul 26th, 2012
When a thread cannot acquire a lock on an object thread enters the waiting state until the lock becomes available .
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What is the difference between a Window and a Frame
The Frame class extends Window to define a main application window that can have amenu bar.
Sandhya.Kishan
- Jul 26th, 2012
A window is a Container and has BorderLayout by default.
A frame is a movable window with title bar and close button,usually it contains Panels. Its derived from a window.
Frame can be part of the window but window can not part of frame. -
What is the purpose of the enableEvents() method
The enableEvents() method is used to enable an event for a particular object. Normally,an event is enabled when a listener is added to an object for a particular event. TheenableEvents() method is used by objects that handle events by overriding their eventdispatchmethods.
Sandhya.Kishan
- Jul 26th, 2012
The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.
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What is the catch or declare rule for method declarations
If a checked exception may be thrown within the body of a method, the method musteither catch theexception or declare it in its throws clause.
Sandhya.Kishan
- Jul 26th, 2012
The catch or declare rule states that if a checked exception is be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause.
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Does garbage collection guarantee that a program will not run out of memory
Garbage collection does not guarantee that a program will not run out of memory. It ispossible forprograms to use up memory resources faster than they are garbage collected. It is alsopossible forprograms to create objects that are not subject to garbage collection
Sandhya.Kishan
- Jul 26th, 2012
The garbage collection is JVM dependent then It is possible for programs to use memory resources faster than they are garbage collected.Moreover garbage collection cannot be enforced,it is just sugges...
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If a method is declared as protected, where may the method be accessed
A protected method may only be accessed by classes or interfaces of the same package orby subclasses ofthe class in which it is declared.
Sandhya.Kishan
- Jul 25th, 2012
The classes or interfaces in which the method is declared can access the protected method.It can also be access within a class through member function and outside a class through public interface.
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How is rounding performed under integer division
The fractional part of the result is truncated. This is known as rounding toward zero.
Sandhya.Kishan
- Jul 25th, 2012
By truncating the fractional part of the result we are rounding the result and this is called as rounding towards zero.
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