How to Get a Synchronized Map from Java HashMap

The example demonstrates how to get a synchronized Map from HashMap by synchronizedMap method in Java.

Source Code

package com.beginner.examples;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class GetSynchronizedMapFromJavaHashMap {

	public static void main(String[] args) {
		//create TreeMap
		HashMap hashMap = new HashMap();
	
		/*
		  Java TreeMap is NOT synchronized. To get synchronized Map from
		  TreeMap use the method synchronizedMap of Collections.
		 */
		Map map = Collections.synchronizedMap(hashMap);
		
		map.put(1,"hello");
		map.put(2,"world");
		
		//Use Collection to output
		Collection collection = map.values();
		Iterator iterator = collection.iterator();
		while (iterator.hasNext()) {
		    System.out.print(iterator.next().toString());
		}

	}

}

Output:

helloworld

References

Imported packages in Java documentation:

• Map
• Collections
• Collection
• HashMap
• Iterator