java/79_Multithreading at main · PeiHui369/java · GitHub

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/* multithreading = Process of executing multiple threads simultaneously
                    Helps maximum utilization of CPU
                    Threads are independent, they don't affect the execution of
                    An exception in one thread will not interrupt other threads
                    useful for serving multiple cilents, multiplayer games, or other mutually independent tasks
 */
<Main.java>
public class Main{
    public static void main(String[] args){
        MyThread thread1 = new MyThread(); //1st method via MyThread.java (subclass)

        //2nd method via MyRunnable.java (class implements runnable runnable interface, pass instance as an argument to Thread arguments)
        MyRunnable runnable1 = new MyRunnable();
        Thread thread2 = new Thread(runnable1);

        thread1.start();
        thread2.start();
    }
}

<MyThread.java>
public class MyThread extends Thread{
    @Override
    public void run(){
        for(int i = 10; i>=0; i--){
            System.out.println("Thread #1: " + i);
            try {
                Thread.sleep(1000); //To set time interval between each loop
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("Thread #1 is finished :)");
    }
}

<MyRunnable.java>
public class MyRunnable implements Runnable{
    @Override
    public void run() {
        for(int i = 0; i<10; i++){
            System.out.println("Thread #2: " +i);
            try {
                Thread.sleep(1000); //To set time interval between each loop
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("Thread #2 is finished :)");
    }
}

>>
Thread #2: 0
Thread #1: 10
Thread #1: 9
Thread #2: 1
Thread #1: 8
Thread #2: 2
Thread #1: 7
Thread #2: 3
Thread #2: 4
Thread #1: 6
Thread #1: 5
Thread #2: 5
Thread #1: 4
Thread #2: 6
Thread #2: 7
Thread #1: 3
Thread #1: 2
Thread #2: 8
Thread #2: 9
Thread #1: 1
Thread #2 is finished :)
Thread #1: 0
Thread #1 is finished :)

<Main.java>
        ...
        thread1.start();
        thread1.join(); //wait thread1 finish, only start thread2
        thread2.start();
        ...
>>
Thread #1: 10
Thread #1: 9
Thread #1: 8
Thread #1: 7
Thread #1: 6
Thread #1: 5
Thread #1: 4
Thread #1: 3
Thread #1: 2
Thread #1: 1
Thread #1: 0
Thread #1 is finished :)
Thread #2: 0
Thread #2: 1
Thread #2: 2
Thread #2: 3
Thread #2: 4
Thread #2: 5
Thread #2: 6
Thread #2: 7
Thread #2: 8
Thread #2: 9
Thread #2 is finished :)

<Main.java>
        ...
        thread1.start();
        thread1.join(3000);//wait thread1 started 3s, only start thread2
        thread2.start();
        ...

>>
Thread #1: 10
Thread #1: 9
Thread #1: 8
Thread #2: 0
Thread #1: 7
Thread #2: 1
Thread #1: 6
Thread #2: 2
Thread #1: 5
Thread #2: 3
Thread #1: 4
Thread #2: 4
Thread #1: 3
Thread #2: 5
Thread #1: 2
Thread #2: 6
Thread #1: 1
Thread #2: 7
Thread #1: 0
Thread #2: 8
Thread #1 is finished :)
Thread #2: 9
Thread #2 is finished :)

//calling thread(ex.main) wait until the specified thread dies or for x milliseconds

-----
/*
daemon thread = background thread (non-user)
JVM will not wait daemon execute

if have 1 user thread
JVM wait to exit until all user thread finish
 */

 ...thread1.setDaemon(true);
    thread2.setDaemon(true);...

    -Terminate if main have exception
    \