java interview questions with answers

Question: What is a native method?
Answer: A native method is a method that is implemented in a language other than Java.

Question: How can you write a loop indefinitely?
Answer: for(;;)--for loop; while(true)--always true, etc.

Question: . Can an anonymous class be declared as implementing an interface and extending a class?
Answer: An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.

Question: What is the purpose of finalization?
Answer: The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.

             





Question: What is the difference between the Boolean & operator and the && operator? 
Answer: If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.
Operator & has no chance to skip both sides evaluation and && operator does. If asked why, give details as above.

Question: What is the GregorianCalendar class?
Answer: The GregorianCalendar provides support for traditional Western calendars.

Question: What is the SimpleTimeZone class?
Answer: The SimpleTimeZone class provides support for a Gregorian calendar.

Question: What is the Properties class?
Answer: The properties class is a subclass of Hashtable that can be read from or written to a stream. It also provides the capability to specify a set of default values to be used.

Question: What is the purpose of the Runtime class?
Answer: The purpose of the Runtime class is to provide access to the Java runtime system.

Question:  What is the purpose of the System class? 
Answer:The purpose of the System class is to provide access to system resources.