Java Thread execution on same data
- by AR89
first of all here is the code, you can just copy an paste
import java.util.ArrayList;
public class RepetionCounter implements Runnable{
private int x;
private int y;
private int[][] matrix;
private int xCounter;
private int yCounter;
private ArrayList<Thread> threadArray;
private int rowIndex;
private boolean[] countCompleted;
public RepetionCounter(int x, int y, int [][]matrix)
{
this.x = x;
this.y = y;
this.matrix = matrix;
this.threadArray = new ArrayList<Thread>(matrix.length);
this.rowIndex = 0;
for(int i = 0; i < matrix.length; i++){
threadArray.add(new Thread(this));
}
countCompleted = new boolean[matrix.length];
}
public void start(){
for (int i = 0; i < threadArray.size(); i++){
threadArray.get(i).start();
this.rowIndex++;
}
}
public void count(int rowIndex)
{
for(int i = 0; i < matrix[rowIndex].length; i++){
if (matrix[rowIndex][i] == x){
this.xCounter++;
} else if (matrix[rowIndex][i] == y){
this.yCounter++;
}
}
}
@Override
public void run() {
count(this.rowIndex);
countCompleted[this.rowIndex] = true;
}
public int getxCounter() {
return xCounter;
}
public void setxCounter(int xCounter) {
this.xCounter = xCounter;
}
public int getyCounter() {
return yCounter;
}
public void setyCounter(int yCounter) {
this.yCounter = yCounter;
}
public boolean[] getCountCompleted() {
return countCompleted;
}
public void setCountCompleted(boolean[] countCompleted) {
this.countCompleted = countCompleted;
}
public static void main(String args[]){
int[][] matrix = {{0,2,1}, {2,3,4}, {3,2,0}};
RepetionCounter rc = new RepetionCounter(0, 2, matrix);
rc.start();
boolean ready = false;
while(!ready){
for(int i = 0; i < matrix.length; i++){
if (rc.getCountCompleted()[i]){
ready = true;
} else {
ready = false;
}
}
}
if (rc.getxCounter() > rc.getyCounter()){
System.out.println("Thre are more x than y");
} else {System.out.println("There are:"+rc.getxCounter()+" x and:"+rc.getyCounter()+" y");
}
}
}
What I want this code to do: I give to the object a matrix and tow numbers, and I want to know how much times these two numbers occurs in the matrix. I create as many thread as the number of rows of the matrix (that' why there is that ArrayList), so in this object I have k threads (supposing k is the number of rows), each of them count the occurrences of the two numbers.
The problem is: if I run it for the first time everything work, but if I try to execute it another time I get and IndexOutOfBoundException, or a bad count of the occurrences, the odd thing is that if I get the error, and modify the code, after that it will works again just for once.
Can you explain to me why is this happening?
