Java Threading

In Java, a thread is a lightweight unit of execution that represents a single sequential flow of control within a program and has separate paths of execution.

Different state of thread:

1. New State
2. Active State
3. Waiting/Blocked State
4. Timed Waiting State
5. Terminated State

We can create thread by

1. Extending Thread class

class ThreadDemo extends Thread{
    @Override
    public void run(){
        System.out.println("Thread started running "+ Thread.currentThread().getName());
    }
}

public class Test{
    public static void main(String[] args) {

        ThreadDemo threadDemo = new ThreadDemo();

        threadDemo.start();
    }
}
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2. implement Runnable interface

class ThreadDemo implements Runnable{
    @Override
    public void run(){
        System.out.println("Thread started running "+ Thread.currentThread().getName());
    }
}

public class Test{
    public static void main(String[] args) {

        ThreadDemo threadDemo = new ThreadDemo();

        Thread thread = new Thread(threadDemo, "thread-1");
        thread.start();
    }
}
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Important method in threading:

1. Wait: Makes the current thread wait until another thread invokes notify() or notifyAll()
2. notify: Wakes up a single thread that is waiting on the object's monitor.
3. join: Waits for the thread to die, i.e., completes execution.
4. sleep: Pauses the current thread for a specified amount of time (in milliseconds)

IMPORTANT POINT

1. The low cost of communication between the processes.