In this post, we will see how to print numbers using multiple threads in java.It is similar to printing odd-even numbers using two threads in java.
Problem
You are given 3 threads. You need to print sequence using these 3 threads.You need to print in natural order up to MAX.
For example:
Let’s say you have 3 threads. T1,T2 and T3.
If MAX is 10, you need to print:
T1 1
T2 2
T3 3
T1 4
T2 5
T3 6
T1 7
T2 8
T3 9
T1 10
T2 2
T3 3
T1 4
T2 5
T3 6
T1 7
T2 8
T3 9
T1 10
Solution
We will use concept of remainder here.
- If number%3==1 then T1 will print the number and increment it else will go in the wait state.
- If number%3==2 then T2 will print the number and increment it else will go in the wait state.
- If number%3==0 then T3 will print the number and increment it else will go in the wait state.
Let me provide simple program for it.
Let’s create a class named "PrintSequenceRunnable" which will implement the Runnable interface.
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public class PrintSequenceRunnable implements Runnable{ public int PRINT_NUMBERS_UPTO=10; static int number=1; int remainder; static Object lock=new Object(); PrintSequenceRunnable(int remainder) { this.remainder=remainder; } @Override public void run() { while (number < PRINT_NUMBERS_UPTO-1) { synchronized (lock) { while (number % 3 != remainder) { // wait for numbers other than remainder try { lock.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + " " + number); number++; lock.notifyAll(); } } } } |
Let’s create a class named "PrintThreadsSequentiallyMain" which will implement the Runnable interface.
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public class PrintThreadsSequentiallyMain { public static void main(String[] args) { PrintSequenceRunnable runnable1=new PrintSequenceRunnable(1); PrintSequenceRunnable runnable2=new PrintSequenceRunnable(2); PrintSequenceRunnable runnable3=new PrintSequenceRunnable(0); Thread t1=new Thread(runnable1,"T1"); Thread t2=new Thread(runnable2,"T2"); Thread t3=new Thread(runnable3,"T3"); t1.start(); t2.start(); t3.start(); } } |
When you run above program, you will get below output.
T1 1
T2 2
T3 3
T1 4
T2 5
T3 6
T1 7
T2 8
T3 9
T1 10
T2 2
T3 3
T1 4
T2 5
T3 6
T1 7
T2 8
T3 9
T1 10
That’s all about printing numbers using multiple threads in java.
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Awesome explanation.
Really remainder concept is amazing