How to make JUnit test cases execute in parallel? [duplicate]

Junit4 provides parallel feature using ParallelComputer:

public class ParallelComputerTest {  

   @Test  
   public void test() {      
      Class[] cls={ParallelTest1.class,ParallelTest2.class };  

      //Parallel among classes  
      JUnitCore.runClasses(ParallelComputer.classes(), cls);  

      //Parallel among methods in a class  
      JUnitCore.runClasses(ParallelComputer.methods(), cls);  

      //Parallel all methods in all classes  
      JUnitCore.runClasses(new ParallelComputer(true, true), cls);     
   } 

   public static class ParallelTest1 {  
      @Test public void a(){}  
      @Test public void b(){}  
   }  

   public static class ParallelTest2 {  
      @Test public void a(){}  
      @Test public void b(){}  
   }  
}