Thread Question

[Simran Dass]

Given the foll Question -

class trd implements Runnable {

     public void run() {
    
       try{
	Thread.sleep(1000);
	System.out.print("Ready to print ");
	domore();
        } catch (Exception e) { }
    }

  public synchronized void domore() throws InterruptedExeption
  {
            wait();
           System.out.print(" printed ")
    }

   public static void main(String [] args) {
     
	Thread t = new Thread(new trd());
	Thread.sleep(5000);
	synchronized(t){
	        System.out.print("now  printing ");
	        t.notifyAll();	
	} 
   }
  }

The options are (Choose 1): -

A) Prints "ready to print , now printing" without any exception
B) Prints "ready to print , now printing,printed" without any exception
c) Run time Exception
d) Compiler error

Answer is a).

Should not it be unpredictable bec' result can be either : -

Prints "ready to print , now printing" without any exception OR
Prints "now printing ,ready to print " without any exception

[pete stein]

Simran Dass wrote:
Given the foll Question -

class trd implements Runnable {

     public void run() {
    
       try{
	Thread.sleep(1000);
	System.out.print("Ready to print ");
	domore();
        } catch (Exception e) { }
    }

  public synchronized void domore() throws InterruptedExeption
  {
            wait();
           System.out.print(" printed ")
    }

   public static void main(String [] args) {
     
	Thread t = new Thread(new trd());
	Thread.sleep(5000);
	synchronized(t){
	        System.out.print("now  printing ");
	        t.notifyAll();	
	} 
   }
  }

There are too many typos and errors present to tell just what this will do. Even if I fix them to get this to compile, the run method is never called as start is not called on any thread.


Edit:
Except, if you do happen to call start on t immediately after it was created, then you'll see your results.

Question: what object is domore synchronized to? What object gets the called with notifyAll()?

[Abimaran Kugathasan]

pete stein wrote:

Simran Dass wrote:
Given the foll Question -

class trd implements Runnable {

     public void run() {
    
       try{
	Thread.sleep(1000);
	System.out.print("Ready to print ");
	domore();
        } catch (Exception e) { }
    }

  public synchronized void domore() throws InterruptedExeption
  {
            wait();
           System.out.print(" printed ")
    }

   public static void main(String [] args) {
     
	Thread t = new Thread(new trd());
	Thread.sleep(5000);
	synchronized(t){
	        System.out.print("now  printing ");
	        t.notifyAll();	
	} 
   }
  }

There are too many typos and errors present to tell just what this will do. Even if I fix them to get this to compile, the run method is never called as start is not called on any thread.


Edit:
Except, if you do happen to call start on t immediately after it was created, then you'll see your results.

Question: what object is domore synchronized to? What object gets the called with notifyAll()?

I think, your question should be like this.

class Trd implements Runnable	{
	public void run()	{
		try	{
			Thread.sleep(1000);
			System.out.println("Ready to print");
			domore();
		} catch(Exception e)	{}
	}
	public synchronized void domore()	throws InterruptedException	{
		wait();
		System.out.println("  Printed ");
	}
	public static void main(String[] args)	{
		Thread t = new Thread(new Trd());
		t.start();// inserted
		synchronized(t)	{
			System.out.println(" Now printing ");
			t.notifyAll();
		}
	}
}

Output :
Now printing
Ready to print


And waiting for a notification, since this will not be notified in future, We have to forcefully exit the code.