Java Synchronized Collections Examples (java.util.Collections)

GDay All,

If you have any of below questions then you are at right place:

• Get Synchronized List from ArrayList example
• How do I synchronize a collection
• How do I synchronize a List or other Collection in Java
• Collections.synchronizedList and synchronized
• java.util.Collections.synchronizedMap() Method Example
• Java Thread Synchronization Tutorial

In this Java example I’ll show how to Synchronized Map and List. We will be using synchronizedMap() method is used to return a synchronized (thread-safe) map backed by the specified map and the same way synchronizedList().

Let’s use List in description. The Collections class provides us with synchronizedList(List list) API method, that returns a synchronized (thread-safe) list from the provided ArrayList.

Steps:

• Create an ArrayList.
• Populate the arrayList with elements, with add(E e) API method of ArrayList.
• Invoke the synchronizedList(List list) API method of Collections to get the synchronized list from the provided ArrayList.

Another must read: How to Serialize Deserialize List of Objects in Java? Java Serialization Example

Let’s take a look at the code snippet:

package com.crunchify.tutorials;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author Crunchify.com
 * 
 */

public class CrunchifySynchronizedListFromArrayList {

	public static void main(String[] args) {

		// ********************** synchronizedList ************************
		ArrayList<String> crunchifyArrayList = new ArrayList<String>();

		// populate the crunchifyArrayList
		crunchifyArrayList.add("eBay");
		crunchifyArrayList.add("Paypal");
		crunchifyArrayList.add("Google");
		crunchifyArrayList.add("Yahoo");

		// Returns a synchronized (thread-safe) list backed by the specified
		// list. In order to guarantee serial access, it is critical that all
		// access to the backing list is accomplished through the returned list.
		List<String> synchronizedList = Collections.synchronizedList(crunchifyArrayList);

		System.out.println("synchronizedList conatins : " + synchronizedList);

		// ********************** synchronizedMap ************************
		Map<String, String> crunchifyMap = new HashMap<String, String>();

		// populate the crunchifyMap
		crunchifyMap.put("1", "eBay");
		crunchifyMap.put("2", "Paypal");
		crunchifyMap.put("3", "Google");
		crunchifyMap.put("4", "Yahoo");

		// create a synchronized map
		Map<String, String> synchronizedMap = Collections.synchronizedMap(crunchifyMap);

		System.out.println("synchronizedMap contains : " + synchronizedMap);
	}
}

Result:

synchronizedList conatins : [eBay, Paypal, Google, Yahoo]
synchronizedMap contains : {3=Google, 2=Paypal, 1=eBay, 4=Yahoo}

The post Java Synchronized Collections Examples (java.util.Collections) appeared first on Crunchify.
Author: Arpit Shah.