How to Temporarily Stop a Thread in Java?

The suspend() method of thread class puts the thread from running to waiting state. This method is employed if you would like to prevent the thread execution and begin it again when a particular event occurs. This method allows a thread to temporarily cease execution. The suspended thread is often resumed using the resume() method. If the present thread cannot modify the target thread then it’ll throw Security Exception.

Note: suspend() method is deprecated in the latest Java version.

Syntax

public final void suspend()

Return: Does not return any value.

Exception: Throws SecurityException If the current thread cannot modify the thread.

Example:

Java

// Java program to demonstrate suspend() method
// of Thread class

import java.io.*;

class GFG extends Thread {
    public void run()
    {
        for (int i = 1; i < 5; i++) {
            try {

                // thread to sleep for 500 milliseconds
                sleep(5);
                System.out.println(
                    "Currently running - "
                    + Thread.currentThread().getName());
            }
            catch (InterruptedException e) {
                System.out.println(e);
            }
            System.out.println(i);
        }
    }
    public static void main(String args[])
    {
        // creating three threads
        GFG t1 = new GFG();
        GFG t2 = new GFG();
        GFG t3 = new GFG();

        // call run() method
        t1.start();
        t2.start();

        // suspend t2 thread
        t2.suspend();

        // call run() method
        t3.start();
    }
}

Output

Note: Thread t2 can be resumed by resume() method.

t2.resume()