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class NewThread extends Thread {
boolean suspendFlag;
NewThread(String threadname, ThreadGroup tgOb) {
super(tgOb, threadname);
suspendFlag = false;
start();
}
public void run() {
try {
for (int i = 5; i > 0; i--) {
System.out.println(getName() + ": " + i);
Thread.sleep(1000);
synchronized (this) {
while (suspendFlag) {
wait();
}
}
}
} catch (Exception e) {
System.out.println("Exception in " + getName());
}
}
void mysuspend() {
suspendFlag = true;
}
synchronized void myresume() {
suspendFlag = false;
notify();
}
}
class ThreadGroupDemo {
public static void main(String args[]) {
ThreadGroup groupA = new ThreadGroup("Group A");
ThreadGroup groupB = new ThreadGroup("Group B");
NewThread ob1 = new NewThread("One", groupA);
NewThread ob2 = new NewThread("Two", groupA);
NewThread ob3 = new NewThread("Three", groupB);
NewThread ob4 = new NewThread("Four", groupB);
groupA.list();
groupB.list();
Thread tga[] = new Thread[groupA.activeCount()];
groupA.enumerate(tga);
for (int i = 0; i < tga.length; i++) {
((NewThread) tga[i]).mysuspend();
}
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
System.out.println("Main thread interrupted.");
}
System.out.println("Resuming Group A");
for (int i = 0; i < tga.length; i++) {
((NewThread) tga[i]).myresume();
}
try {
ob1.join();
ob2.join();
ob3.join();
ob4.join();
} catch (Exception e) {
System.out.println("Exception in Main thread");
}
}
}
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