Multitasking in Multithreading

How to perform single task by multiple threads?

If you have to perform single task by many threads, have only one run() method.For example:

Program of performing single task by multiple threads

1. class TestMultitasking1 extends Thread{  
2.  public void run(){  
3.    System.out.println("task one");  
4.  }  
5.  public static void main(String args[]){  
6.   TestMultitasking1 t1=new TestMultitasking1();  
7.   TestMultitasking1 t2=new TestMultitasking1();  
8.   TestMultitasking1 t3=new TestMultitasking1();  
9.   
10.   t1.start();  
11.   t2.start();  
12.   t3.start();  
13.  }  
14. }  

Output:task one
       task one
       task one

Program of performing single task by multiple threads

1. class TestMultitasking2 implements Runnable{  
2. public void run(){  
3. System.out.println("task one");  
4. }  
5.   
6. public static void main(String args[]){  
7. Thread t1 =new Thread(new TestMultitasking2());//passing annonymous object of TestMultitasking2 class  
8. Thread t2 =new Thread(new TestMultitasking2());  
9.   
10. t1.start();  
11. t2.start();  
12.   
13.  }  
14. }  

Output:task one
       task one

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Note: Each thread run in a separate callstack.

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How to perform multiple tasks by multiple threads (multitasking in multithreading)?

If you have to perform multiple tasks by multiple threads,have multiple run() methods.For example:

Program of performing two tasks by two threads

1. class Simple1 extends Thread{  
2.  public void run(){  
3.    System.out.println("task one");  
4.  }  
5. }  
6.   
7. class Simple2 extends Thread{  
8.  public void run(){  
9.    System.out.println("task two");  
10.  }  
11. }  
12.   
13.  class TestMultitasking3{  
14.  public static void main(String args[]){  
15.   Simple1 t1=new Simple1();  
16.   Simple2 t2=new Simple2();  
17.   
18.   t1.start();  
19.   t2.start();  
20.  }  
21. }  

Output:task one
       task two

Same example as above by annonymous class that extends Thread class:

Program of performing two tasks by two threads

1. class TestMultitasking4{  
2.  public static void main(String args[]){  
3.   Thread t1=new Thread(){  
4.     public void run(){  
5.       System.out.println("task one");  
6.     }  
7.   };  
8.   Thread t2=new Thread(){  
9.     public void run(){  
10.       System.out.println("task two");  
11.     }  
12.   };  
13.   
14.   
15.   t1.start();  
16.   t2.start();  
17.  }  
18. }  

Output:task one
       task two

Same example as above by annonymous class that implements Runnable interface:

Program of performing two tasks by two threads

1. class TestMultitasking5{  
2.  public static void main(String args[]){  
3.   Runnable r1=new Runnable(){  
4.     public void run(){  
5.       System.out.println("task one");  
6.     }  
7.   };  
8.   
9.   Runnable r2=new Runnable(){  
10.     public void run(){  
11.       System.out.println("task two");  
12.     }  
13.   };  
14.       
15.   Thread t1=new Thread(r1);  
16.   Thread t2=new Thread(r2);  
17.   
18.   t1.start();  
19.   t2.start();  
20.  }  
21. }  

Output:task one
       task two