JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to get entry set from HashMap?


Description:

Below example shows how to get all key-value pair as Entry objects. Entry class provides getter methods to access key-value details. The method entrySet() provides all entries as set object.


Code:
package com.java2novice.hashmap;

import java.util.HashMap;
import java.util.Map.Entry;
import java.util.Set;

public class MyHashMapEntrySet {

	public static void main(String a[]){
		HashMap<String, String> hm = new HashMap<String, String>();
		//add key-value pair to hashmap
		hm.put("first", "FIRST INSERTED");
		hm.put("second", "SECOND INSERTED");
		hm.put("third","THIRD INSERTED");
		System.out.println(hm);
		//getting value for the given key from hashmap
		Set<Entry<String, String>> entires = hm.entrySet();
		for(Entry<String,String> ent:entires){
			System.out.println(ent.getKey()+" ==> "+ent.getValue());
		}
	}
}

Output:
{second=SECOND INSERTED, third=THIRD INSERTED, first=FIRST INSERTED}
second ==> SECOND INSERTED
third ==> THIRD INSERTED
first ==> FIRST INSERTED
<< Previous Program | Next Program >>

List Of All HashMap Sample Programs:

  1. Basic HashMap Operations.
  2. How to iterate through HashMap?
  3. How to copy Map content to another HashMap?
  4. How to search a key in HashMap?
  5. How to search a value in HashMap?
  6. How to get all keys from HashMap?
  7. How to get entry set from HashMap?
  8. How to delete all elements from HashMap?
  9. How to eliminate duplicate user defined objects as a key from HashMap?
  10. How to find user defined objects as a key from HashMap?
  11. How to delete user defined objects as a key from HashMap?
Knowledge Centre
What is abstract class or abstract method?
We cannot create instance for an abstract class. We can able to create instance for its subclass only. By specifying abstract keyword just before class, we can make a class as abstract class.

public abstract class MyAbstractClass{

}

Abstract class may or may not contains abstract methods. Abstract method is just method signature, it does not containes any implementation. Its subclass must provide implementation for abstract methods. Abstract methods are looks like as given below:

public abstract int getLength();
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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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