Java Thread interrupt() method

The interrupt() method of thread class is used to interrupt the thread. If any thread is in sleeping or waiting state (i.e. sleep() or wait() is invoked) then using the interrupt() method, we can interrupt the thread execution by throwing InterruptedException.

If the thread is not in the sleeping or waiting state then calling the interrupt() method performs a normal behavior and doesn't interrupt the thread but sets the interrupt flag to true.

Syntax

Return

This method does not return any value.

Exception

SecurityException: This exception throws if the current thread cannot modify the thread.

Example 1: Interrupting a thread that stops working

In this program, after interrupting the thread, we throw a new exception so it will stop working.

public class JavaInterruptExp1 extends Thread
{  
    public void run()
    {  
        try
        {  
            Thread.sleep(1000);  
            System.out.println("javatpoint");  
        }catch(InterruptedException e){  
            throw new RuntimeException("Thread interrupted..."+e);
            
        }  
    }  
    public static void main(String args[])
    {  
        JavaInterruptExp1 t1=new JavaInterruptExp1();  
        t1.start();  
        try
        {  
            t1.interrupt();  
        }catch(Exception e){System.out.println("Exception handled "+e);}  
    }  
}  

Test it Now

Output:

Exception in thread "Thread-0" java.lang.RuntimeException: Thread interrupted...java.lang.InterruptedException: sleep interrupted
	at JavaInterruptExp1.run(JavaInterruptExp1.java:10)

Example 2: Interrupting a thread that doesn't stop working

In this example, after interrupting the thread, we handle the exception, so it will break out from the sleeping state but will not stop working.

public class JavaInterruptExp2 extends Thread
{  
    public void run()
    {  
        try
        {  
            //Here current threads goes to sleeping state
            // Another thread gets the chance to execute
            Thread.sleep(500);  
            System.out.println("javatpoint");  
        }catch(InterruptedException e){  
            System.out.println("Exception handled "+e);  
        }  
        System.out.println("thread is running...");  
    }  
    public static void main(String args[])
    {  
        JavaInterruptExp2 t1=new JavaInterruptExp2();  
         JavaInterruptExp2 t2=new JavaInterruptExp2();
        // call run() method 
        t1.start(); 
        // interrupt the thread 
        t1.interrupt();  
    }  
} 

Test it Now

Output:

Exception handled java.lang.InterruptedException: sleep interrupted
thread is running...

Example 3: Interrupting a thread that behaves normally

In this program, there is no exception occurred during the thread execution. Here, interrupt() method only sets the interrupted flag to true that can be used to stop the thread by the Java programmer later.

public class JavaInterruptExp3 extends Thread
{  
    public void run()
    {  
        for(int i=1; i<=5; i++)  
            System.out.println(i);  
    }  
    public static void main(String args[])
    {  
        JavaInterruptExp3 t1=new JavaInterruptExp3();  
        // call run() method
        t1.start();  
        t1.interrupt();  
    }  
}  

Test it Now

Output:

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