78_Threads

/*
thread = A thread of execution in a program(kind of like a virtual CPU
         The JVM allows an application to have multiple thread running concurrently
         Each thread can execute parts of your code in parallel with the main thread
         Each thread has a priority.
         Threads with higher priority are executed in preference compared to threads with a lower priority

         The Java Virtual Machine continues to execute threads until either of the following occurs
         1. The exit method of class Runtime has been called
         2. All user threads have died

         When a JVM starts up, there is a thread which calls the main method
         This thread is called "main"

         Daemon thread is a low priority thread that runs in background to perform tasks such as garbage collection
         JVM terminates itself when all user threads (non-daemon threads) finish their execution
         -daemon has low priority
        
 */

<Main.java>
public class Main{
    public static void main(String[] args) throws InterruptedException {
        System.out.println(Thread.activeCount());
        //>>1 [ which is main thread]

        System.out.println(Thread.currentThread().getName());
        //>>main

        Thread.currentThread().setName("MAINNN");
        System.out.println(Thread.currentThread().getName());
        //>>MAINNNN

        System.out.println(Thread.currentThread().getPriority());
        //>>5 [Number of priority of main thread]

        Thread.currentThread().setPriority(10);//10 highest, 1 lowest
        System.out.println(Thread.currentThread().getPriority());
        //>>10

        System.out.println(Thread.currentThread().isAlive());
        //>>true

        //counter countdown by seconds
        for(int i = 3; i>0; i--){
            System.out.println(i);
            Thread.sleep(1000); //Time set is in millisecond
        /*>>
3
2
1
-Each appear in time interval of 1s
         */

        }
        System.out.println("You are done!");
        // >>You are done! when all the {} done run

        MyThread thread2 = new MyThread();

        System.out.println(thread2.isAlive());
        //>>false

        thread2.start();
        System.out.println(thread2.isAlive());
        //>>true
        //  This thread is running

        thread2.run();
        System.out.println(thread2.isAlive());
        //>>This thread is running
        //  false

        System.out.println(thread2.getName());
        //>>Thread-0

        thread2.setName("2nd thread");
        System.out.println(thread2.getName());
        //>>2nd thread

        System.out.println(thread2.getPriority());
        //>>5 [default]

        thread2.setPriority(1);
        System.out.println(thread2.getPriority());
        //>>1

        //Check to see how many thread active

        System.out.println(Thread.activeCount());
        //>>2 [after thread2.start()]

        System.out.println(thread2.isDaemon());
        //>>false
        //  This is a user thread that is running

        thread2.setDaemon(true);
        System.out.println(thread2.isDaemon());
        //>>true
        //  This is a daemon thread that is running        
    }
}

<MyThread.java>
public class MyThread extends Thread{
    @Override
    public void run(){
        if(this.isDaemon()){
            System.out.println("This is a daemon thread that is running");
        }
        else{
            System.out.println("This is a user thread that is running");
        }
    }
}