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Java Collections - Collections.synchronizedList() Examples

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> List<T> synchronizedList(List<T> list)

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


Examples


package com.logicbig.example.collections;

import java.util.ArrayList;
import java.util.Collections;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class SynchronizedListExample {

    public static void main(String... args) throws InterruptedException {
        ArrayList<Integer> list = new ArrayList<>();
        Collections.addAll(list, new Integer[10000]);
        System.out.println("initial size: " + list.size());

        final ExecutorService e = Executors.newFixedThreadPool(10);
        int size = list.size();
        for (int i = 0; i < size; i++) {
            e.execute(() -> list.remove(0));
        }
        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(list.size());//should be zero
    }
}

Output

initial size: 10000
164




Using synchronizedList 

package com.logicbig.example.collections;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class SynchronizedListExample2 {

    public static void main(String... args) throws InterruptedException {
        List<Integer> integers = new ArrayList<>();
        List<Integer> list = Collections.synchronizedList(integers);
        Collections.addAll(list, new Integer[10000]);
        System.out.println("initial size: " + list.size());

        final ExecutorService e = Executors.newFixedThreadPool(10);
        int size = list.size();
        for (int i = 0; i < size; i++) {
            e.execute(() -> {
                list.remove(0);
            });
        }
        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(list.size());//should be zero
    }
}

Output

initial size: 10000
0

See Also