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This wikiHow will teach you how to run multiple threads in Java. You'll want to run multiple threads to create a program that processes multiple actions at once; the more CPU your computer has, the more processes it can run concurrently.

  1.  public 
     void 
     run 
     ( 
     ) 
    
    • This code provides a beginning point for your multiple threads to run.
  2.  Thread 
     ( 
     Runnable 
     threadObj 
     , 
     String 
     threadName 
     ); 
    
    • ' threadObj ' is the class that starts the runnable thread and ' threadName ' is the name of the thread.
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  3.  void 
     start 
     (); 
    
    • Use this code after you've fleshed out a thread object and this code will start it.
    • Your finished code could look like this
       class 
       RunnableDemo 
       implements 
       Runnable 
       { 
       private 
       Thread 
       t 
       ; 
       private 
       String 
       threadName 
       ; 
       RunnableDemo 
       ( 
       String 
       name 
       ) 
       { 
       threadName 
       = 
       name 
       ; 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Creating " 
       + 
       threadName 
       ); 
       } 
       public 
       void 
       run 
       () 
       { 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Running " 
       + 
       threadName 
       ); 
       try 
       { 
       for 
       ( 
       int 
       i 
       = 
       4 
       ; 
       i 
       > 
       0 
       ; 
       i 
       --) 
       { 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Thread: " 
       + 
       threadName 
       + 
       ", " 
       + 
       i 
       ); 
       // Let the thread sleep for a while. 
       Thread 
       . 
       sleep 
       ( 
       50 
       ); 
       } 
       } 
       catch 
       ( 
       InterruptedException 
       e 
       ) 
       { 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Thread " 
       + 
       threadName 
       + 
       " interrupted." 
       ); 
       } 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Thread " 
       + 
       threadName 
       + 
       " exiting." 
       ); 
       } 
       public 
       void 
       start 
       () 
       { 
       System 
       . 
       out 
       . 
       println 
       ( 
       "Starting " 
       + 
       threadName 
       ); 
       if 
       ( 
       t 
       == 
       null 
       ) 
       { 
       t 
       = 
       new 
       Thread 
       ( 
       this 
       , 
       threadName 
       ); 
       t 
       . 
       start 
       (); 
       } 
       } 
       } 
       public 
       class 
       TestThread 
       { 
       public 
       static 
       void 
       main 
       ( 
       String 
       args 
       []) 
       { 
       RunnableDemo 
       R1 
       = 
       new 
       RunnableDemo 
       ( 
       "Thread-1" 
       ); 
       R1 
       . 
       start 
       (); 
       RunnableDemo 
       R2 
       = 
       new 
       RunnableDemo 
       ( 
       "Thread-2" 
       ); 
       R2 
       . 
       start 
       (); 
       } 
       } 
      
  4. If you used the coding from the example, the output should read
     Creating 
     Thread 
     - 
     1 
     Starting 
     Thread 
     - 
     1 
     Creating 
     Thread 
     - 
     2 
     Starting 
     Thread 
     - 
     2 
     Running 
     Thread 
     - 
     1 
     Thread: 
     Thread 
     - 
     1 
     , 
     4 
     Running 
     Thread 
     - 
     2 
     Thread: 
     Thread 
     - 
     2 
     , 
     4 
     Thread: 
     Thread 
     - 
     1 
     , 
     3 
     Thread: 
     Thread 
     - 
     2 
     , 
     3 
     Thread: 
     Thread 
     - 
     1 
     , 
     2 
     Thread: 
     Thread 
     - 
     2 
     , 
     2 
     Thread: 
     Thread 
     - 
     1 
     , 
     1 
     Thread: 
     Thread 
     - 
     2 
     , 
     1 
     Thread 
     Thread 
     - 
     1 
     exiting 
     . 
     Thread 
     Thread 
     - 
     2 
     exiting 
     . 
    
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      About This Article

      Article Summary X

      1. Enter public void run ( ) into your code.
      2. Use Thread(runnable threadObj, String threadName); in your code.
      3. Enter void start (); in your code.
      4. Execute your code.

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