Thread Part II - Stop the Thread and MultiThreading in java

Thread Part II
Stop the Thread and MultiThreading in java

Every thread that has been executed will be stop after every code in run() is finished executed, method will be automatic stop, but it doesn’t mean we can’t stop thread every time we want, we can stop thread using method stop(), but this method not recommended because the method is deprecated, the best thing that we can do by using boolean variable for controlling looping process.

Let’s see the example,

public class MyThreadStop extends Thread {

   private boolean finish = false;

   public void run() {

      int counter = 0;

      System.out.println("the child thread is executed...");

      while (!finish) {

        System.out.print((++counter) + " ");

       }

       System.out.println("the child thread is ended ");

      } 

// method as flag trigger to stop looping, once this method is

// invoke

   public void stopThread() {

    finish = true;

   }

}

No matter what in method run looping or not, as long as we give flag to stop the method run(), we can stop our thread as we see the code bellow

public class MyThreadStopDemo {

public static void main(String[]args)throws InterruptedException{

  

  System.out.println("the main thread is executed...");

  MyThreadStop myThreadStop = new MyThreadStop();

  myThreadStop.start();

  Thread.sleep(25);

 // triggering method to stop child thread

  myThreadStop.stopThread();

  System.out.println("\nEnd main Thread ");

  

  }

}

for code above we see that we didn’t called stop() method belong to the thread we just call a method stop contain a flag for stopping process in run() method.

in java program we need more than one child thread, program that contain thread more than one child thread called multithreaded. To prove java can handle multithreading we create two threads and invoke the two threads in demo class.

First thread :

public class MyThreadOne extends Thread{

   public void run(){

     try {

       for (int i = 0; i <10 ; i++) {

            System.out.println("First thread : "+(i+1));

            if( i!= 9){

               sleep(1000);

             }else{

              System.out.println("First thread finish....\n");

              }

            }

    }catch (InterruptedException e) {

      e.printStackTrace();

    }

   }

}

second thread :

public class MyThreadTwo extends Thread{

   public void run(){

     try {

       for (int i = 0; i < 5 ; i++) {

           System.out.println("Second thread :"+(i+1));

           if( i!= 4){

             sleep(1000);

             }else{

             System.out.println("Second thread finish....\n");

            }

           }

     } catch (InterruptedException e) {

       e.printStackTrace();

      }

    }

}

now we will call both thread

public class MutipleThreadDemo {

   public static void main(String[] args) {

    MyThreadOne myThreadOne = new MyThreadOne();

    myThreadOne.start();

    MyThreadTwo myThreadTwo = new MyThreadTwo();

    myThreadTwo.start();

   }

}

and if we execute demo class the result as shown bellow

First thread : 1

Second thread : 1

Second thread : 2

First thread : 2

First thread : 3

Second thread : 3

Second thread : 4

First thread : 4

First thread : 5

Second thread : 5

Second thread finish....

First thread : 6

First thread : 7

First thread : 8

First thread : 9

First thread : 10

First thread finish....

 

we see the result the first five line has same value it showed thread were executed together, after the sixth second running, second thread finished. Because only five looping steps for second thread. as the result above java has multithreading feature.

Thread Part IV - Determine Thread Priority in Java

Thread Part IV

Thread Priority

Thread Priority is set which thread to be priority to execute first, in theory the thread with the higher priority will be get more time CPU then the lower priority thread, the value of priority is MIN_PRIORITY to MAX_PRIORITY is 1 to 10 and for normal priority NORM_PRIORITY is 5. for determine priority in thread we use method setPriority() and to get the value priority we use method getPriority() both are belong to thread class. Ok let’s try how both method work, the idea was to figure how many looping created for high priority and low priority. First we created generated thread as shown bellow,

public class MyThreadPriority implements Runnable{

  private Thread thread;

  private long n;

  private boolean finish = false;

  MyThreadPriority(String name, int priority){

   thread = new Thread(this, name);

   thread.setPriority(priority);

  }

  @Override

  public void run() {

    while (!finish) {

     n++;

    }

  }

 public void start(){

  thread.start();

 }

 public void stop(){

  finish = true;

 }

 public long getN(){

  return n;

  }

 public Thread getThread(){

   return thread;

 }

}

 

then we try to create demonstration to check how priority work

public class PriorityThreadDemo {

public static void main(String[]args)throws InterruptedException{

  MyThreadPriority t1= new MyThreadPriority("high", 

  Thread.NORM_PRIORITY+ 2);

  MyThreadPriority t2 = new MyThreadPriority("low", 

  Thread.NORM_PRIORITY-2);

  t1.start();

  t2.start();

  Thread.sleep(5000);

  t1.stop();

  t2.stop();

  t1.getThread().join();

  t2.getThread().join();

  System.out.println("The number of looping for "+

  t1.getThread().getName()+" thread priority" +" : "+ t1.getN());

  System.out.println("The number of looping for "+

  t2.getThread().getName()+" thread priority" +" : "+ t2.getN());

  }

}

if we run the class above the console will show look like bellow,

The number of looping for high thread priority : 1351468823

The number of looping for low thread priority : 1301962925

from the result above the higher priority thread will do many looping than the lower one, and the value of looping above will be different for every CPU speed and how many applications running, but all will show the higher priority will do many looping than the lower one.