In below given example, the Parent thread dies before
the Child thread.
class
ChildThread1 extends Thread {
@Override
public void run() {
try {
System.out.println("Child thread start");
Thread th = Thread.currentThread();
if("Child Thread".equals(th.getName())) {
Thread.sleep(1000);
}
System.out.println("Child thread closed");
} catch(Exception e) {
System.out.println("exception is" + e);
}
}
}
public class
CloseChildThreadTest {
public static void main(String
args[]) throws InterruptedException {
System.out.println("Main thread start");
ChildThread1 cThread = new ChildThread1();
cThread.setName("Child Thread");
cThread.start();
System.out.println("Main thread closed");
}
}
Output:
Main thread start
Main thread closed
Child thread start
Child thread closed
Ensure the parent dies after the Child thread?
1. Using join() method
class
ChildThread1 extends Thread {
@Override
public void run() {
try {
System.out.println("Child thread start");
Thread th = Thread.currentThread();
if("Child Thread".equals(th.getName())) {
Thread.sleep(1000);
}
System.out.println("Child thread closed");
} catch(Exception e) {
System.out.println("exception is" + e);
}
}
}
public class
CloseChildThreadTest {
public static void main(String
args[]) throws InterruptedException {
System.out.println("Main thread start");
ChildThread1 cThread = new ChildThread1();
cThread.setName("Child Thread");
cThread.start();
cThread.join();
System.out.println("Main thread closed");
}
}
Output:
Main thread start
Child thread start
Child thread closed
Main thread closed
Using
CountDownLatch:
package com.thread;
import
java.util.concurrent.CountDownLatch;
class
ChildThread1 extends Thread {
CountDownLatch latch;
public
ChildThread1(CountDownLatch latch) {
this.latch = latch;
}
@Override
public void run() {
try {
System.out.println("Child thread start");
Thread th = Thread.currentThread();
if("Child Thread".equals(th.getName())) {
Thread.sleep(1000);
}
System.out.println("Child thread closed");
/* Count down when the run method execution finished. */
latch.countDown();
} catch(Exception e) {
System.out.println("exception is" + e);
}
}
}
public class
CloseChildThreadTest {
public static void main(String
args[]) throws InterruptedException {
/*Set count 1 to CountDownLatch. */
CountDownLatch latch = new CountDownLatch(1);
System.out.println("Main thread start");
ChildThread1 cThread = new ChildThread1(latch);
cThread.setName("Child Thread");
cThread.start();
/* Await till the end of the Child thread. */
latch.await();
System.out.println("Main thread closed");
}
}
Output:
Main thread start
Child thread start
Child thread closed
Main thread closed
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