Find Max Value of 10 Threads

Question

I have a program that sorts though a text file and pulls out the maximum value using 10 threads. How can I then sort through the 10 threads and find the highest value of those 10? My logic would be to store each result in an array and compare that result to the previous, but I'm unsure on how to properly implement it with threading. I added this for loop but it's not correct.Any help would be greatly appreciated!

 for (int x = 0; max <=max; x++) {
                max = worker.getMax();
                System.out.println("Final Max " = max);
            }

This is the actual program including the code above. It runs fine without this.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class datafile{

    public static void main(String[] args) throws IOException {
        int[] array = new int[100000];
        int count;
        int index = 0;
        String datafile = "dataset529.txt"; //string which contains datafile
        String line; //current line of text file

        try (BufferedReader br = new BufferedReader(new FileReader(datafile))) { //reads in the datafile
            while ((line = br.readLine()) != null) { //reads through each line
                array[index++] = Integer.parseInt(line); //pulls out the number of each line and puts it in numbers[]
            }
        }



        Thread[] threads = new Thread[10];
        worker[] workers = new worker[10];


        int range = array.length / 10;
        for (count = 0; count < 10; count++) {
            int startAt = count * range;
            int endAt = startAt + range;
            workers[count] = new worker(startAt, endAt, array);

        }

        for (count = 0; count < 10; count++) {
            threads[count] = new Thread(workers[count]);
            threads[count].start();
        }

        boolean isProcessing = false;
        do {
            isProcessing = false;
            for (Thread t : threads) {
                if (t.isAlive()) {
                    isProcessing = true;
                    break;
                }
            }
        } while (isProcessing);

        for (worker worker : workers) {
            System.out.println("Max = " + worker.getMax());
        }

        for (int x = 0; max <=max; x++) {
            max = worker.getMax();
            System.out.println("Final Max " = max);
        }

    }


    public static class worker implements Runnable {

        private int startAt;
        private int endAt;
        private int randomNumbers[];

        int max = Integer.MIN_VALUE;

        public worker(int startAt, int endAt, int[] randomNumbers) {
            this.startAt = startAt;
            this.endAt = endAt;
            this.randomNumbers = randomNumbers;
        }

        @Override
        public void run() {
            for (int index = startAt; index < endAt; index++) {

                if (randomNumbers != null && randomNumbers[index] > max)
                    max = randomNumbers[index];
            }
        }

        public int getMax() {
            return max;
        }

    }
}

what is incorrect? what result do you get ? – vvg Nov 01 '15 at 22:47 — vvg, Nov 01 '15 at 22:47

Sneh · Accepted Answer · 2015-11-01T22:59:13.757

1

Basically your max calculation was wrong. Here is the corrected code.

int finalMax = workers[0].getMax(); //Sets max as first worker's max

for (int x = 1; x < workers.length; x++) {
     if(finalMax < workers[x].getMax())//checks whether finalMax is less than worker's max at x'th position and if yes assigns it to finalMax         
        finalMax = workers[x].getMax();        
}

System.out.println("Final Max " + finalMax );

edited Nov 01 '15 at 22:59

answered Nov 01 '15 at 22:48

Sneh

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Hmmm. Seems close but when i try to execute, it says that Error:(54, 24) java: cannot find symbol symbol: variable worker location: class datafile Additionally, it says an expression is expected for this line. – Vortex11 Nov 01 '15 at 22:53
Also, changed worker[0].getMax() to workers[0].getMax() Thanks for your help, I marked you as accepted and voted you up! – Vortex11 Nov 01 '15 at 22:58
arghh, should stop using my phone to answer. – Sneh Nov 01 '15 at 22:59
No worries! Much appreciated! – Vortex11 Nov 01 '15 at 23:00

Find Max Value of 10 Threads

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