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Archive for January 14, 2009

Java Program to show Thread Synchronization – Q28

January 14, 2009 Leave a comment

Q28: Java Program to show that if three threads are of equal priority and they are not synchronized then more than one thread may be executing in single function which give wrong values. Output ([hello[dear[bhaskar]]]).

class Callme{
	void call(String msg){
		System.out.print("[" + msg);
		try{
			Thread.sleep(1000);
		}
		catch(InterruptedException e){
			System.out.println("Interrupted");
		}
		System.out.println("]");
	}
}

class Caller implements Runnable{
	String msg;
	Callme target;
	Thread t;
	public Caller(Callme targ, String s){
		target = targ;
		msg = s;
		t = new Thread(this);
		t.start();
	}
	public void run(){
		target.call(msg);
	}
}

class Synch{
	public static void main(String args[]){
		Callme target = new Callme();
		Caller ob1 = new Caller(target, "Hello");
		Caller ob2 = new Caller(target, "Dear");
		Caller ob3 = new Caller(target, "Manoj");
		try{
			ob1.t.join();
			ob2.t.join();
			ob3.t.join();
		}
		catch(InterruptedException e){
			System.out.println("Interrupted");
		}
	}
}

… from College notes (BCA/MCA assignments):


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Java Program to show implement Low & High priority Threads – Q27

January 14, 2009 Leave a comment

Q27: Java Program to create clicker class which sets the priority of two threads (one is having high priority and one is having low priority) and whenever the thread is running it is increasing a counter. In the end print what is the value of the counter for both of the threads.

class clicker implements Runnable{
	int click=0;
	Thread t;
	private volatile boolean running=true;
	
	public clicker(int p){
		t = new Thread(this);
		t.setPriority(p);
	}
	
	public void run(){
		while(running){
			click++;
		}
	}
	
	public void stop(){
		running=false;
	}
	
	public void start(){
		t.start();
	}
}

class HiLoPri{

	public static void main(String args[]){
		Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
		clicker hi = new clicker(Thread.NORM_PRIORITY+2);
		clicker lo = new clicker(Thread.NORM_PRIORITY-2);
		
		lo.start();
		hi.start();
		
		try{
			Thread.sleep(1000);
		}
		catch(InterruptedException e){
			System.out.println("Main thread interrupted.");
		}
		
		lo.stop();
		hi.stop();
		
		try{
			hi.t.join();
			lo.t.join();
		}
		catch(InterruptedException e){
			System.out.println("InterruptedException caught");
		}

		System.out.println("Low-Prioritythread value: " + lo.click);
		System.out.println("High-Prioritythread value: " + hi.click);
	}
}

… from College notes (BCA/MCA assignments):