About Question enthuware.scjp.v6.2.497 :

[anilkumarv]

Code: Select all

public class TestClass extends Thread{
	String name = "";
	public TestClass(String str){
		name = str;
	}
	public void run(){
		try{
			Thread.sleep( (int) (Math.random()*5000) );
			System.out.println(name);    
		}
		catch(Exception e)
		{
		}
	}
	public static void main(String[] str) throws Exception{
		Thread t1 = new TestClass("tom");
		Thread t2 = new TestClass("dick");
		t1.start();
		t2.start();
		t1.join();
		t2.join();
		System.out.println("harry");
	}
}

The main thread waits for t1 and t2 to complete the execution , so only the last print statement is guaranteed to print last. What changes in the code is required if I need to ensure that tom, dick and harry is printed sequentially.Can thread priorities help ?.

[anilkumarv]

Code: Select all

public class TestClass extends Thread{
   String name = "";
   public TestClass(String str){
      name = str;
   }
   public void run(){
      try{
         Thread.sleep( (int) (Math.random()*5000) );
         System.out.println(name);    
      }
      catch(Exception e)
      {
      }
   }
   public static void main(String[] str) throws Exception{
      Thread t1 = new TestClass("tom");
      Thread t2 = new TestClass("dick");
      t1.start();      
      t1.join();
      t2.start();//Thread t2 won't start untill t1 is complete
      t2.join();
      System.out.println("harry");
   }
}

So the above code snippet will always print
tom
dick
harry
Kindly confirm.

[admin]

So the above code snippet will always print
tom
dick
harry
Kindly confirm.

No, that is not correct. Please go through the explanation. It explains why.

[anilkumarv]

So the above code snippet will always print
tom
dick
harry
Kindly confirm.

No, that is not correct. Please go through the explanation. It explains why.

I have gone through the explanation given.
Original code:

Code: Select all

t1.start();
t2.start();
t1.join();
t2.join();

Modified code

Code: Select all

t1.start();
t1.join();//t1 will run to its completion and then invoke t2.
t2.start();
t2.join();

Kindly confirm if my understanding is correct.

[admin]

Yes, that is correct.