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Java Collections - Collections.synchronizedNavigableSet() Examples

[Last Updated: Nov 8, 2025]

Java Collections Java Java API 

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Class:

java.util.Collections

java.lang.Objectjava.lang.Objectjava.util.Collectionsjava.util.CollectionsLogicBig

Method:

public static <T> NavigableSet<T> synchronizedNavigableSet(NavigableSet<T> s)

Returns a synchronized (thread-safe) NavigableSet backed by the specified NavigableSet.


Examples


Without synchronization: 

package com.logicbig.example.collections;

import java.util.NavigableSet;
import java.util.TreeSet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class SynchronizedNavigableSetExample {
    private static AtomicInteger atomicInteger = new AtomicInteger(0);

    public static void main(String... args) throws InterruptedException {
        NavigableSet<Integer> theSet = new TreeSet<>();

        final ExecutorService e = Executors.newFixedThreadPool(1000);
        for (int i = 1; i <= 1000; i++) {

            e.execute(() -> {
                int n = atomicInteger.incrementAndGet();
                try {
                    theSet.add(n);
                } catch (Exception e1) {
                    //may throw exceptions when not synchronized
                    System.out.println(e1 + " " + n);
                }
            });
        }

        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(theSet.size());//should be 1000
    }
}

Output

999




Using Collections.synchronizedNavigableSet: 

package com.logicbig.example.collections;

import java.util.Collections;
import java.util.NavigableSet;
import java.util.TreeSet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class SynchronizedNavigableSetExample2 {

    private static AtomicInteger atomicInteger = new AtomicInteger(0);

    public static void main(String... args) throws InterruptedException {
        NavigableSet<Integer> s = new TreeSet<>();
        NavigableSet<Integer> theSet = Collections.synchronizedNavigableSet(s);

        final ExecutorService e = Executors.newFixedThreadPool(1000);
        for (int i = 1; i <= 1000; i++) {
            e.execute(() -> {
                int n = atomicInteger.incrementAndGet();
                try {
                    theSet.add(n);
                } catch (Exception e1) {
                    //may throw exceptions when not synchronized
                    System.out.println(e1 + " " + n);
                }
            });
        }
        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(theSet.size());//should be 1000
    }
}

Output

1000

See Also