JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to compare two sets and retain elements which are same on both sets?


Description:

Below example shows how to compare two sets, and retain the values which are common on both set objects. By calling retainAll() method you can do this operation.


Code:
package com.java2novice.hashset;

import java.util.HashSet;

public class MyHashSetRetain {

	public static void main(String a[]){
		HashSet<String> hs = new HashSet<String>();
		//add elements to HashSet
		hs.add("first");
		hs.add("second");
		hs.add("third");
		hs.add("apple");
		hs.add("rat");
		System.out.println(hs);
		HashSet<String> subSet = new HashSet<String>();
		subSet.add("rat");
		subSet.add("second");
		subSet.add("first");
		hs.retainAll(subSet);
		System.out.println("HashSet content:");
		System.out.println(hs);
	}
}

Output:
[second, apple, rat, third, first]
HashSet content:
[second, rat, first]
<< Previous Program | Next Program >>

List Of All HashSet Sample Programs:

  1. Basic HashSet Operations.
  2. How to iterate through HashSet?
  3. How to copy Set content to another HashSet?
  4. How to delete all elements from HashSet?
  5. How to copy all elements from HashSet to an array?
  6. How to compare two sets and retain elements which are same on both sets?
  7. How to eliminate duplicate user defined objects from HashSet?
  8. How to find user defined objects from HashSet?
  9. How to delete user defined objects from HashSet?
Knowledge Centre
What is wrapper class?
Everything in java is an object, except primitives. Primitives are int, short, long, boolean, etc. Since they are not objects, they cannot return as objects, and collection of objects. To support this, java provides wrapper classes to move primitives to objects. Some of the wrapper classes are Integer, Long, Boolean, etc.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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