Thread states

Definition

A thread is in one of a few states: NEW (created, not started), RUNNABLE (running or ready), BLOCKED (waiting for a lock), WAITING or TIMED_WAITING (waiting for another thread or a timer), and TERMINATED (finished).

Example code

Watching one thread move through its states

class Demo {
    public static void main(String[] args) throws InterruptedException {
        Thread worker = new Thread(() -> {
            try {
                Thread.sleep(300);                         // the thread waits with a timer
            } catch (InterruptedException ignored) { }
        });

        System.out.println(worker.getState());             // NEW
        worker.start();
        Thread.sleep(100);
        System.out.println(worker.getState());             // TIMED_WAITING: it is inside sleep
        worker.join();
        System.out.println(worker.getState());             // TERMINATED
    }
}

// Output:
// NEW
// TIMED_WAITING
// TERMINATED