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Hashmap and Hashtable
which one is better and faster between hashmap and hashtable? Explain the situation where you would use them ?
sampra
- Mar 13th, 2012
HashMap is Faster then Hashtable because Hashtable has synchronized method so use Hashtable when you want synchronization other wise prefer HashMap
Naga Sudheer
- Jul 28th, 2011
Hashmap is not synchronized where as HashTable is synchronized. HashMap is faster than HashTable at the cost of synchronization and there is no point of null and value pairs in HashTable where as in HashMap it exists..so HashMap is faster than HashTable
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How are memory leaks possible in Java
sampra
- Mar 13th, 2012
When we have object in momory and that object is not gets called at runtime.this is memory leckage
bikash
- Jul 20th, 2011
Improper handling of pointers leads to memory leaks and reliability issues.
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Which class is the super class for all classes in java.lang package?
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Sort an Arraylist having Group of Objects
Employee object having emp name, emp id, emp salary... An arraylist has a list of employee object.How will you sort this arraylist?
Gaurav Singh
- Jul 13th, 2011
Implement the Comparator Interface for the Employee Class. Then customize your sort in the implemented method from interface
NGKiran
- Mar 15th, 2011
Implement Comparable interface for the class Employee, customize your require in the implemented method from interface
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Abstract - How do you make object
If all the methods in the Abstract class is defined, then it is a Abstract class? And can we make object out of it?
sampra
- Mar 16th, 2012
We cant create the instance of abstract class ..here we need sub class which extended this class .we can have ref var of abstract class
Amit Khaware
- Jun 29th, 2011
First thing first, An abstract class without any abstract method means you are loosing the main intent fo abstractness, why we are making abstract class is to provide some of common implementation and...
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How does garbage collection work
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What happens if we execute the program?class Return{ int display(){ try{ return 1; } finally{ return 2; }}public static void main(String args[]){ Return r=new Return(); r.display();}}when i executed i got the compile time error when i executed on jdk 1.4?but in khalid moghal book its executed and result is printed.
Pallu
- Sep 5th, 2006
You are right Sandeep.But I guess, Sadashivrao did not set a classpath if he is executing this program on command prompt.You can set classpath by:(if u saved Return.java in temp folder)C:Documents and Settingsx.yDesktoptemp>set classpath=%classpath%;C:Documents and Settingsx.yDesktoptemp
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What is the Repeater function...and What does Data Integrity means?
Sandhya.Kishan
- Mar 17th, 2012
The correctness and consistency of stored data is known as integrity of data.
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Taking the Build.
What is mean by taking "build"? And Which processes and modules of an application involved while taking Builds.
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Explain When Java Application can run out of memory ?
Anon
- Apr 12th, 2012
If you have an infinite loop that keeps on doing things that take up memory (like creating objects).
sampra
- Mar 6th, 2012
We all know Java automatically garbage collects unused objects. But you must remember that an object is considered as unused only when the object no longer referenced. That means a referenced class continues to exist and to take up memory space even if it is not used.
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What happens if public static void main(){} is made protected?
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Editorial / Best Answer
Answered by: Sushil Jain
- Nov 21st, 2007
You will be able to compile but it will through a run time error saying "main method not public".
AA
- Apr 22nd, 2012
It will compile but gives error at run time......
divya_mini4u
- Sep 21st, 2010
The complier will throw error that there is no main()? method. main() should be public always please note.
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What are the differences between ArrayList and a Vector
YUVARAJ
- May 11th, 2012
Array is a set of related data type and static whereas vector is a grow able array of objects and dynamic
sampra
- Mar 13th, 2012
AL-non legecy/methods are not sysnchronized
Vector-legecy/method are synchronized -
What is difference between checked and unchecked exception ?
inderjeet singh
- May 12th, 2012
Checked Exception represents the External Failure while Unchecked Exception represents the Internal failure.
muktasharad
- Sep 5th, 2008
checked exceptions must be handeled.That is, a try-catch must either be nested around the call to the method that throws the exception.The compiler will throw an ...
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What are the difference between java.sql package and javax.sql package
vijay
- May 18th, 2012
Javax.sql provides connection pooling ,distributed transaction,disconnected rowsets
sampra
- Feb 15th, 2008
Java.sql.* package is used for the basic jdbc connections.javax.sql.* package is used for the advance jdbc. Advance is connection pooling, rowsets...ect.
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Why class Class is always the Super Class for every class
ashish
- May 20th, 2012
1. Object is super class for all java classes.
2. even if someone want to make a class as subclass of CLASS class, he cant because class class is declared as final. so it can not be inheritedvinaymudgil007
- Jun 12th, 2008
Java.lang.Object is the super class of all classes and NOT Class classvinny
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Exception Handling
What is the output of the following program, When tested under JDK 5.0class ExceptionDemo{ public static void main(String[] args) { int a[] = new int[] {1,2,3,4,5}; try{ System.out.prinltln(a[6]); } catch(Exception e) { System.out.println("Catching Exception ..."); } catch(ArrayIndexOutofBoundsException ae) { System.out.println("Catching ArrayIndexOutOfBounds...
kuchipudi Prasad
- May 31st, 2012
Output is "catching exception"
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Core Java Interview Questions
Ans