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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 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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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 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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Which Component subclass is used for drawing and painting
Canvas
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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. -
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 Checkbox method allows you to tell if a Checkbox is checked
getState()
Sandhya.Kishan
- May 7th, 2012
The method which is used to check whether the checkbox is checked or not is the getstate() method.
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What is a void return type
A void return type indicates that a method does not return a value.
Sandhya.Kishan
- May 7th, 2012
Void return type specifies that the particular function will not return any value.
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If an object is garbage collected, can it become reachable again
Once an object is garbage collected, it ceases to exist. It can no longer become reachableagain.
Sandhya.Kishan
- May 7th, 2012
An object reaches the garbage collector as it becomes unreachable ,hence once an object is garbage collected it cannot be made reachable again.
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Under what conditions is an object's finalize() method invoked by the garbagecollector
The garbage collector invokes an object's finalize() method when it detects that the objecthas become unreachable.
Sandhya.Kishan
- May 7th, 2012
When an object becomes unreachable by any of the methods in a program then the finalize() method in invoked.
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What's new with the stop(), suspend() and resume() methods in JDK 1.2
The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.
Sandhya.Kishan
- May 8th, 2012
The stop(), suspend() and resume() methods are marked as obsolete to warn against its use in the future so that it may be phased out.
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How does Java handle integer overflows and underflows
It uses those low order bytes of the result that can fit into the size of the type allowed bythe operation.
Sandhya.Kishan
- May 11th, 2012
Java do not handle integer overflow or underflow it just wraps round the value be adding 1 to the maximum values which returns the minimum value.
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What invokes a thread's run() method
After a thread is started, via its start() method or that of the Thread class, the JVMinvokes the thread'srun() method when the thread is initially executed.
Sandhya.Kishan
- May 11th, 2012
A thread starts its process by invoking the start() method, this start() method invokes the run() method.
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Can an anonymous class be declared as implementing an interface andextending a class
An anonymous class may implement an interface or extend a superclass, but may not bedeclared to doboth.
Sandhya.Kishan
- May 11th, 2012
An anonymous class simultaneously cannot be declared as implementing an interface and extending a class but it may implement an interface or extend a superclass.
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Can a double value be cast to a byte
Yes, a double value can be cast to a byte.
Sandhya.Kishan
- May 11th, 2012
Any data type can be typecasted to any other data type and hence we can type cast a double value to a byte.
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What is the argument type of a program's main() method
A program's main() method takes an argument of the String[] type.
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What modifiers may be used with an inner class that is a member of an outerclass
A (non-local) inner class may be declared as public, protected, private, static, final, orabstract.
Sandhya.Kishan
- May 11th, 2012
Expect static modifier all other modifiers such public,private,protected,default,abstract and final modifiers can be used with inner class which is a member of an outer-class.
If the inner class contains the static modifier it results in compilation error. -
What is SAX?
Sandhya.Kishan
- May 16th, 2012
SAX defines an abstract programmatic interface that models the XML information set (infoset) through a linear sequence of familiar method calls.They are used to develop standard for the events-based parsing of XML documents.
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What is context?
Sandhya.Kishan
- May 16th, 2012
Context is the virtual environment required to suspend a running software program.The concept of context assumes significance in the case of interruptible tasks, wherein upon being interrupted the processor saves the context and proceeds to serve the Interrupt service routine
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