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Thread Basics

Thread Basics


1-      Thread Creation :
There are two ways of creating a new thread.

Way-1 Implementing Runnable Interface:
public class CustRunnable implements Runnable {

    public void run() {
        System.out.println("Executed !");
    }

    public static void main(String args[]) {
        Thread myThread =  new Thread(new CustRunnable());
        myThread.start()
    }
}

Way-2 Extending Thread Interface:
public class CustThread extends Thread {

    public void run() {
        System.out.println("Executed from a new thread!");
    }

    public static void main(String args[]) {
        CustThread myThread = new CustThread();
        myThread.start();
    }
}

First way is preferable. Because it leaves the flexibility of extending another class and compatible with higher level thread management APIs.
2 -      Important Thread Methods

-    public static void sleep(long millis) throws InterruptedException

public static void sleep(long millis, int nanos) throws    InterruptedException

Executing threads goes to sleep for specified times amount. Puts thread into TIMED_WAITING state. Thread doesn’t leave locks it obtains. If thread is interrupted during sleep, InterruptedException is raised.

-          public void interrupt()

Used to interrupt a thread. When a thread is interrupted it stops what it is doing and does some thing in respose to interrupt.

Generally threads respond to interrupts by stopping execution. A typical respond is as in the example.

public void run() {
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            return;// stop execution
        }
      }

Thread related methods tend to throw InterruptedException. If a thread is not invoking a method that throws InterruptedException, a thread my check interrupt status by calling Thread.interrupted()method.
·         Remember after throwing InterruptedException or returning true to static Thread.interrupted() method, thread’s internal interrupt status flag is cleared.
·         The non-static version of interrupted() method doesn’t clear interrupt status flag.

-          public final void join() throws InterruptedException

public final void join(long millis) throws InterruptedException

public final void join(long millis,int nanos) throws InterruptedException

Allows a thread to pause execution until another thread finishes execution. Puts  thread into WAITING state. Overloaded versions allows to specfy a timeout value and puts thread into  TIMED_WAITING state.


May throw InterruptedException .

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