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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 19th, 2012
A Boolean type is automatically initialized to value 0 or false value.
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Can try statements be nested
Try statements may be tested.
ashfaq02
- May 1st, 2008
Yes, try statements can be nested . first the inner statements will be executed .
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What is the purpose of a statement block
A statement block is used to organize a sequence of statements as a single statementgroup.
Sandhya.Kishan
- May 19th, 2012
Statements that are of a sequence are organized as a single statement group with the help of statement block.
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What modifiers may be used with a top-level class
A top-level class may be public, abstract, or final.
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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 24th, 2012
When an object becomes unreachable to the program in which it is being used then an object subjects to the garbage collection.
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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 methods are used to get and set the text label displayed by a Buttonobject
getLabel() and setLabel()
Sandhya.Kishan
- Jul 24th, 2012
The methods used to get and set the text label are GetLabel() and SetLabel() methods.
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Which Component subclass is used for drawing and painting
Canvas
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What is the List interface
The List interface provides support for ordered collections of objects.
Sandhya.Kishan
- May 22nd, 2012
List interface extends collection interface.List interface is used for positional access,search,iteration and for range view operations.
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Is the ternary operator written x : y ? z or x ? y : z ?
It is written x ? y : z.
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Q: What is it object serialization ?
Serialization is a way to convert objects (including complex data structures such as lists and trees) into a stream of bytes.
Sandhya.Kishan
- Jun 11th, 2012
Serialization is a process of conversion of an object to a series of bytes.Such that the object can be stored easily in the persistent memory.The byte stream can then be deserialised i.e,converted into a replica of the original object.
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Q: What is it reflection (introspection) ? Why is reflection possible in the Java language?
Reflection (introspection) is querying a class about its properties, and operating on methods and fields by the name for a given object instance. Reflection is possible in the Java language because of late binding.
Mithun Challa
- Jan 8th, 2008
There are generally two types of reflection1) Introspection2) IntercessionIn Interospection we can see the features of a class or object of our interest using the methods available. Java just supports...
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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 are abstract classes, abstract methods?
Simply speaking a class or a method qualified with "abstract" keyword is an abstract class or abstract method. You create an abstract class when you want to manipulate a set of classes through a common interface. All derived-class methods that match the signature of the base-class declaration will be called using the dynamic binding mechanism. An abstract method is an incomplete method. It has only...
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What are native methods? How do you use them?
Native methods are methods that are defined as public static methods within a java class, but whose implementation is provided in another programming language such as C.
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Are constructors inherited? Can a subclass call the parent's class constructor? When?
You cannot inherit a constructor. That is, you cannot create a instance of a subclass using a constructor of one of it's superclasses. One of the main reasons is because you probably don't want to overide the superclasses constructor, which would be possible if they were inherited. By giving the developer the ability to override a superclasses constructor you would erode the encapsulation abilities...
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Does Java have destructors?
No garbage collector does the job working in the background
Sandhya.Kishan
- May 22nd, 2012
Java does not support destructors, since java supports the concept of garbage collection,hence the garbage collector is used to automatically free the space which has occupied by the program while run...
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Name four methods every Java class will have.
public String toString();public Object clone();public boolean equals();public int hashCode();
Sandhya.Kishan
- Jun 11th, 2012
Every Java class will have
1.public String toString();
2.public Object clone();
3.public boolean equals();
4.public int hashCode(); -
Are there any other 'marker' interfaces?
java.rmi.Remotejava.util.EventListener
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What do you mean by static methods?
By using the static method there is no need creating an object of that class to use that method. We can directly call that method on that class. For example, say class A has static function f(), then we can call f() function as A.f(). There is no need of creating an object of class A.
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