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Why was Java Created?
PlatForm Indepentdent ,security,Garbage Collection.
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Class hierarchy of HashMap is as follows
"HashMap extends AbstractMap implements Map"
When AbstractMap implements Map interface and AbstractMap is extended by HashMap, what is the use of again implementing Map interface in the declaration of HashMap?.">Class hierarchy of AbstractMap is as follows "AbstractMap implements Map"Class hierarchy of HashMap is as follows "HashMap extends AbstractMap implements Map"When AbstractMap implements Map interface and AbstractMap is extended by HashMap, what is the use of again implementing Map interface in the declaration of HashMap?.
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What is the difference between servlets and applets?
Servlets are to servers. Applets are to browsers. Unlike applets, however, servlets have no graphical user interface.
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Which class should you use to obtain design information about an object
The Class class is used to obtain information about an object's design.
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What is the purpose of the System class
The purpose of the System class is to provide access to system resources.
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What is the difference between yielding and sleeping
When a task invokes its yield() method, it returns to the ready state. When a task invokesits sleep()method, it returns to the waiting state.
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Which characters may be used as the second character of an identifier, but notas the firstcharacter of an identifier
The digits 0 through 9 may not be used as the first character of an identifier but they maybe used after thefirst character of an identifier.
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What is the Collections API
The Collections API is a set of classes and interfaces that support operations oncollections of objects.
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Can a lock be acquired on a class
Yes, a lock can be acquired on a class. This lock is acquired on the class's Class object.
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What is the purpose of the wait(), notify(), and notifyAll() methods
The wait(),notify(), and notifyAll() methods are used to provide an efficient way forthreads to wait for a shared resource. When a thread executes an object's wait() method, itenters the waiting state. It only enters the ready state after another thread invokes theobject's notify() or notifyAll() methods..
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How are commas used in the intialization and iteration parts of a for statement
Commas are used to separate multiple statements within the initialization and iterationparts of a for statement.
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What is the purpose of the Runtime class
The purpose of the Runtime class is to provide access to the Java runtime system.
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Is null a keyword
The null value is not a keyword.
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How are Observer and Observable used
Objects that subclass the Observable class maintain a list of observers. When anObservable object is updated it invokes the update() method of each of its observers tonotify the observers that it has changed state. The Observer interface is implemented byobjects that observe Observable objects.