Java Collections synchronizedNavigableMap() Method

The synchronizedNavigableMap() method of Java Collections class is used to get a synchronized (thread-safe) navigable map backed by the specified navigable map.

Syntax

Following is the declaration of synchronizedNavigableMap() method:

public static <K,V> NavigableMap<K,V> synchronizedNavigableMap(NavigableMap<K,V> m)

Parameter

Parameter	Description	Required/Optional
m	It is the navigable map which will be wrapped in a synchronized navigable map.	Required

Returns

The synchronizedNavigableMap() method returns a synchronized view of the specified Navigable Map.

Exceptions

Compatibility Version

Java 1.8 and above

Example 1

import java.util.*;
public class CollectionsSynchronizedNavigableMapExample1 {
	public static void main(String[] args) {
		NavigableMap<String, String> map = new TreeMap<String, String>();
		map.put("3", "Java");
		map.put("4", "JavaTpoint");
		map.put("2", "Facebook");
		map.put("1", "Google");
		Map<String, String> synmap = Collections.synchronizedNavigableMap(map);
		System.out.println("Synchronized navigable map is :" + synmap);	            
	      }
}

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Output:

Synchronized navigable map is :{1=Google, 2=Facebook, 3=Java, 4=JavaTpoint}

Example 2

import java.util.*;
public class CollectionsSynchronizedNavigableMapExample2 {
	public static void main(String[] args) {
		NavigableMap<Integer, Integer> map = new TreeMap<>();
		map.put(1, 1001);
		map.put(2, 1002);
		map.put(3, 1003);
		map.put(4, 1004);
		map.put(5, 1005);
		System.out.println("Map before Synchronized navigable map: " + map);
		Map<Integer, Integer> synmap = Collections.synchronizedNavigableMap(map);	
	     map.remove(4, 1004);
	     System.out.println("Synchronized navigable map after remove(4, 1004):" + synmap);
	     }
}

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Output:

Map before Synchronized map: {1=1001, 2=1002, 3=1003, 4=1004, 5=1005}
Synchronized map after remove(4, 1004):{1=1001, 2=1002, 3=1003, 5=1005}

Example 3

import java.util.Collections;
import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
public class CollectionsSynchronizedNavigableMapExample3 {
    private static AtomicInteger counter = new AtomicInteger();
    public static void main(String[] args) throws InterruptedException {
        NavigableMap<Integer, Integer> m = new TreeMap<>();
        NavigableMap<Integer, Integer> map = Collections.synchronizedNavigableMap(m);
        final ExecutorService e = Executors.newFixedThreadPool(10);
        for (int i = 0; i < 10; i++) {
            e.execute(() -> map.put(counter.incrementAndGet(),
                    (int) (Math.random() * 100)));
        }
        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(map.size());//should be 10
    }
}

Test it Now

Output:

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