JAVA Tutorial : Thread , Multi Thread Example

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Today, we are going to learn about Thread in JAVA.

simpleThread.java Class

 public class simpleThread implements Runnable {
 /*
  What is Thread in JAVA Programming? 
  Ans: Thread is a path of execution within a program. Multi Threading is multiple path
  of execution at the same time. Thread is a way, how your computer allows you to do
  multiple things at once. This is the simplest definition of thread.
   
   Now, how we will be working with Thread in practice?
   
   Step 1: Creating a thread object from thread class
   Step 2: Then we will start thread
   Step 3: Just to start, thread will look for RUN method.
   Step 4: While finds run method, the code into the RUN method
   will be executed.
  
   we will be implementing Runnable interface here.
  * */
 
 
 
 public static void main(String[] args) {

  System.out.println("Downloading two files..:");
  // we are creating a thread object below
  Thread t1 = new Thread() {
   /* 
    After t1.start , execution comes here to look for run
    Then the codes in run should be executed.
    
    */
   public void run() {
    for (int k = 0; k <= 20; k++) {
     System.out.println("File 1 downloaded " + k * 5 + "%");
    
     try {
      // Let the thread sleep for 1200 mili seconds.
      sleep(1200);
     } catch (InterruptedException threadExep) {
      threadExep.printStackTrace();
     }
    }

   }

  };
  // now, this will call run method
  t1.start();

  Thread t2 = new Thread() {
   public void run() {
    for (int k = 0; k <= 20; k++) {
     System.out.println("File 2 Downloaded " + k * 5 + "%");

     try {
      sleep(1000);
     } catch (InterruptedException threadExep) {
      threadExep.printStackTrace();
     }
    }

   }

  };

  t2.start();

  
  /*
   Using Runnable Interface(run method must be overridden):
   
   Step 1: We will Create an object of the class. Which is obj1 here.
   Step 2: Create a thread object and pass the class object through it
   Step 3: Start the thread, do operation.
   
   */
  simpleThread obj1 = new simpleThread();
  Thread t3 = new Thread(obj1);
  t3.start();
  
  
  /*
   
    This can be written as: 
    
   Thread t3 = new Thread(new simpleThread());
   t3.start();  
  
   * */
   
 }

 @Override
 public void run() {
  for (int p = 0; p <= 10; p++) {
   System.out.println("This is my T3 thread!");
  
  }
  
 }


}

/*
 
  What we are doing here:
  Creating couple of thread T1, T2. Then both starts and prints a for loop 
  while both sleeps for 1200 and 1000 mili seconds respectively.
 See the outputs!
 */

Output is:

Downloading two files..:

File 1 downloaded 0%

File 2 Downloaded 0%

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

This is my T3 thread!

File 2 Downloaded 5%

File 1 downloaded 5%

File 2 Downloaded 10%

File 1 downloaded 10%

File 2 Downloaded 15%

File 1 downloaded 15%

File 2 Downloaded 20%

File 1 downloaded 20%

File 2 Downloaded 25%

File 2 Downloaded 30%

File 1 downloaded 25%

File 2 Downloaded 35%

File 1 downloaded 30%

File 2 Downloaded 40%

File 1 downloaded 35%

File 2 Downloaded 45%

File 1 downloaded 40%

File 2 Downloaded 50%

File 1 downloaded 45%

File 2 Downloaded 55%

File 1 downloaded 50%

File 2 Downloaded 60%

File 2 Downloaded 65%

File 1 downloaded 55%

File 2 Downloaded 70%

File 1 downloaded 60%

File 2 Downloaded 75%

File 1 downloaded 65%

File 2 Downloaded 80%

File 1 downloaded 70%

File 2 Downloaded 85%

File 1 downloaded 75%

File 2 Downloaded 90%

File 2 Downloaded 95%

File 1 downloaded 80%

File 2 Downloaded 100%

File 1 downloaded 85%

File 1 downloaded 90%

File 1 downloaded 95%

File 1 downloaded 100%