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Q:

What do you know about the big-O notation and can you give some examples with respect to different data structures ? 

Answer:



Q:

Which of the following are incorrect form of StringBuffer class constructor  ?

A) StringBuffer(int size , String str) B) StringBuffer(int size)
C) StringBuffer(String str) D) StringBuffer()
 
Answer & Explanation Answer: A) StringBuffer(int size , String str)

Explanation:
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Filed Under: Java - Technology
Job Role: Database Administration , IT Trainer

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Q:

Does not overriding hashcode() method has any performance implication ?

Answer

A poor Hashcode() function will result in frequent collision in HashMap which eventually increase time for adding an object into Hash Map.

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Subject: Java - Technology
Job Role: Analyst , IT Trainer

1 17
Q:

How do you handle error condition while writing stored procedure or accessing stored procedure from java ?

Answer

Stored procedure should return error code if some operation fails but if stored procedure itself fail than catching SQLException is only choice.

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Subject: Java - Technology

1 24
Q:

What is the difference between creating String as new() and literal ?

Answer

When we create string with new() Operator, it’s created in heap and not added into string pool while String created using literal are created in String pool itself which exists in PermGen area of heap.



String s = new String("Test");

does not put the object in String pool , we need to call String.intern() method which is used to put them into String pool explicitly. its only when you create String object as String literal e.g. String s = "Test" Java automatically put that into String pool.

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1 83
Q:

What is immutable object? Can you write immutable object ?

Answer

Immutable classes are Java classes whose objects can not be modified once created. Any modification in Immutable object result in new object. For example is String is immutable in Java. Mostly Immutable are also final in Java, in order to prevent sub class from overriding methods in Java which can compromise Immutability. You can achieve same functionality by making member as non final but private and not modifying them except in constructor.

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