import java.util.concurrent.BrokenBarrierException;

import java.util.concurrent.CyclicBarrier;

public class CyclicBarrierDemo{

public static void main(String[] args){

float[][] matrix = new float[3][3];

int counter = 0;

for(int row=0;row<matrix.length;row++){

for(int col =0 ; col<matrix[0].length; col++){

matrix[row][col] = counter++;

}

}

dump(matrix);

System.out.println();

Solver solver = new Solver(matrix);

System.out.println();

dump(matrix);

}

static void dump(float[][] matrix){

for(int row =0;row<matrix.length;row++){

for(int col=0;col<matrix[0].length;col++){

System.out.print(matrix[row][col] + " ");

}

System.out.println();

}

}

}

class Solver{

final int N;

final float[][] data;

final CyclicBarrier barrier;

class WorkerTask implements Runnable{

int myRow;

boolean done = false;

WorkerTask(int row){

myRow = row;

}

boolean done(){

return done;

}

void processRow(int myRow){

System.out.println(Thread.currentThread() + " processing row: " + myRow);

for(int i=0;i<data[myRow].length;i++){

data[myRow][i]*=10;

}

done = true;

}

@Override

public void run(){

while(!done()){

processRow(myRow);

try{

barrier.await(); // Not tripped till all parties wait at the barrier :)

}catch(InterruptedException ie){

ie.printStackTrace();

return;

}catch(BrokenBarrierException bbe){

bbe.printStackTrace();

return;

}

}

}

}

public Solver(float[][] matrix){

data = matrix;

N = matrix.length;

barrier = new CyclicBarrier(N, new Runnable(){

@Override

public void run(){

mergeRows(); // execute when the barrier tripped.

}

});

for(int i=0;i<N;i++){

new Thread(new WorkerTask(i)).start();

}

waitUntilDone();

}

void mergeRows(){

System.out.println(Thread.currentThread() + "merging simulating.");

synchronized("abc"){

"abc".notify();

}

}

void waitUntilDone(){

synchronized("abc"){

try{

System.out.println(Thread.currentThread() + " is waiting.");

"abc".wait();

System.out.println(Thread.currentThread() + " is notified.");

}catch(InterruptedException ie){

System.out.println(Thread.currentThread() + " is interrupted.");

}

}

}

}