Threads state

[Girish Nagaraj]

Assume that a set of threads are accessing the same object in synchronization.

What will be the state of other threads when one of thread has acquired Lock of that object?

[Shaliey Gowtham]

Blocked state

[Edwin Dalorzo]

Blocked

[Amirr Rafique]

What will be the state of other threads when one of thread has acquired Lock of that object?

Won't the thread be in waiting state

[Edwin Dalorzo]

Nope! It is blocked.

See JDK API

This will prove it.

import java.util.concurrent.TimeUnit;
 
public class Question8 {
Thread t1, t2;
 
public static void main(String[] args) {
 
//This is the shared resource
Question8 shared = new Question8();
 
//Create to threads and pass them the shared resource
shared.t1 = new StateTest("T1", shared);
shared.t2 = new StateTest("T2", shared);
 
//Start the threads
shared.t1.start();
shared.t2.start();
 
}
 
//The two thread are going to race for this method
public synchronized void catchMeIfYouCan() {
while (!Thread.currentThread().isInterrupted()) {
System.out.println("I am hold by: "
+ Thread.currentThread().getName());
printMyState(t1);
printMyState(t2);
try {
TimeUnit.SECONDS.sleep(3);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
 
//This method simply prints the state of a thread
public void printMyState(Thread t) {
if (t.getState() == Thread.State.NEW)
System.out.println(t.getName() + " state is NEW");
else if (t.getState() == Thread.State.BLOCKED)
System.out.println(t.getName() + " state is BLOCKED");
else if (t.getState() == Thread.State.WAITING)
System.out.println(t.getName() + " state is WAITING");
else if (t.getState() == Thread.State.RUNNABLE)
System.out.println(t.getName() + " state is RUNNABLE");
else if (t.getState() == Thread.State.TIMED_WAITING)
System.out.println(t.getName() + " state is TIME_WAITING");
else if (t.getState() == Thread.State.TERMINATED)
System.out.println(t.getName() + " state is TERMINATED");
else
System.out.println(t.getName() + " is in another state");
}
 
public static class StateTest extends Thread {
Question8 question;
 
public StateTest(String name, Question8 question) {
super(name);
this.question = question;
}
 
public void run() {
//Start race condition, the first thread will hold the lock forever.
//the order will block
this.question.catchMeIfYouCan();
}
}
}

[Pramila Chinguru]

Hi
There are only five states a thread can be in.
new,runnable,running,blocked,dead.
Blocked state includes when a thread is put to sleep using sleep method, or when a thread is waiting for an object lock is blocked using wait/notify protocol.
Go through this tutorial. Hope that helps.

[Ashok S Yadav]

pramila,
The link that you have inserted in your message takes me to a page that says that a thread can be in one of the four states:
1. New
2. Runnable
3. Dead
4. Blocked.
Any thoughts on this. I am working my 1.4 certification. Thread is one topic that is really giving me headaches.

Thanks

[Pramila Chinguru]

Hi Ashok,
Any thread which is ready for execution(waiting for CPU time) would be kept in runnable pool. Once it gets CPU time(currently executing) then it is in Running state.