Thread: MergeSort not working Helppp please :(

I've been working on this mergeSort that has to read from a file then give me the size and then print out the sorted array. However it's giving me the size and printing out the list without sorting it... Helppp please

Here's my code:

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.util.Scanner;
 
/**
 *
 * @author fluffy
 */
public class Numbers {
 
    int[] data;
    int size;
 
    Numbers(String fileName) throws IOException {
        data = openFile(fileName);
        data = mergeSort(data);
 
        for (int i = 0; i < data.length; i = i + 1) {
            System.out.println("*" + data[i]);
        }
    }
 
    public int[] openFile(String fileName) throws
            IOException, ArrayIndexOutOfBoundsException,
            InputMismatchException, NoSuchElementException {
 
        int[] a = new int[10];
        int i = 0;
        int k = 0;
        try {
            File inFile = new File(fileName);
            Scanner in = new Scanner(inFile);
 
            //while(in.hasNext()){
            do {
 
                try {
                    k = in.nextInt();
 
                    try {
 
                        a[i] = k;
                    } catch (ArrayIndexOutOfBoundsException e) {
                        System.out.println("Array bound error");
                        a = grow(a);
                        a[i] = k;
                    }
                    i = i + 1;
                } catch (InputMismatchException e) {
                    in.next();
                }
            } while (true);
 
 
        } catch (IOException e) {
            //System.out.println("File 2 not found in openFile3  " + e.getMessage());
        } catch (NoSuchElementException e) {
            size = i - 1;
        }
 
        System.out.println("Size of the array " + size);
 
        return a;
    }
 
    private static int[] grow(int[] a) {
        int[] b = new int[(a.length) * 2];
        for (int i = 0; i <
                a.length; i =
                        i + 1) {
            b[i] = a[i];
        }
 
        return b;
 
    }
 
    public static int[] mergeSort(int[] data) {
        if (data.length > 1) {
 
            int mid = data.length / 2;
 
            int[] first = new int[mid];
            int[] second = new int[data.length - mid];
 
            for (int i = 0; i < first.length; i = i + 1) {
                first[i] = data[i];
            }
            for (int i = 0; i < second.length; i = i + 1) {
                second[i] = data[i + mid];
            }
 
            first = mergeSort(first);
            second = mergeSort(second);
            data = merge(first, second);
 
        }
 
        return data;
    }
 
 
    public static int[] merge(int[] first, int[] second) {
        int i = 0, j = 0;
        int k = 0;
        int[] mergeData = new int[first.length + second.length];
 
        if (i < first.length && j < second.length) {
            if (first[i] < second[j]) {
                mergeData[k] = first[i];
                i = i + 1;
                k = k + 1;
            } else {
                mergeData[k] = second[j];
                j = j + 1;
                k = k + 1;
            }
 
            for (; i < first.length; i = i + 1) {
                mergeData[k] = first[i];
                k = k + 1;
            }
            for (; j < second.length; j = j + 1) {
                mergeData[k] = second[j];
                k = k + 1;
            }
 
 
        }
        return mergeData;
    }
}

Your MergeSort method never returns the sorted list.

    public static int[] mergeSort(int[] data) {
        if (data.length > 1) {
 
            int mid = data.length / 2;
 
            int[] first = new int[mid];
            int[] second = new int[data.length - mid];
 
            for (int i = 0; i < first.length; i = i + 1) {
                first[i] = data[i];
            }
            for (int i = 0; i < second.length; i = i + 1) {
                second[i] = data[i + mid];
            }
 
            first = mergeSort(first);
            second = mergeSort(second);
            data = merge(first, second);
            [b]return data;[/b] // need this line
        }

Ahh, didn't look through it that closely ::blush::
dlorde's right, there is a flaw in your merge method. Do what he says and see if you can figure out what it is