mergsort printing a strange result - double

Question

I am having an issue with my merge sort, when I print out my sortedArray it only returns [ 0.0, 0.0.....] Im not sure if there is an error in my sort code or in my print line or if it has to do with doubles. The code I am us posted below.
By calling System.out.println(toString(sortedArray) I get an even more obscure answer.
Thanks for any help.
package mergesort;
import java.util.Arrays;
import java.util.Random;
public class mergesort {
public static void main(String[] args) {
double[] array = getIntArray();
long before = System.nanoTime();
double[] sortedArray= mergeSort(array);
System.out.println("Sorting took "+ (System.nanoTime() - before) +" nanoseconds ");
System.out.println(toString(array) + "\n\n" + toString(sortedArray) + "\n main method completed in: " + (System.nanoTime() - before) + " nanoseconds.");
}
private static String toString(double[] array) {
StringBuilder sb = new StringBuilder("[ ");
double len = array.length;
for(int i = 0; i < len - 1; i++) {
sb.append(array[i] + ", ");
}
sb.append(array[(int) (len - 1)] + " ]");
return sb.toString();
}
public static double[] mergeSort(double[] array) {
if (array.length <= 1) {
return array;
}
int half = array.length / 2;
return merge(mergeSort(Arrays.copyOfRange(array, 0, half)),
mergeSort(Arrays.copyOfRange(array, half, array.length)));
}
private static double[] merge(double[] ds, double[] ds2) {
int len1 = ds.length, len2 = ds2.length;
int totalLength = len1 + len2;
double[] result = new double[totalLength];
int counterForLeft =0,counterForRight=0,resultIndex=0;
while(counterForLeft<len1 || counterForRight < len2){
if(counterForLeft<len1 && counterForRight < len2){
if(ds[counterForLeft]<= ds2[counterForRight]){
result[resultIndex++] =(int) ds[counterForLeft++];
} else {
result[resultIndex++] =(int) ds2[counterForRight++];
}
}else if(counterForLeft<len1){
result[resultIndex++] = (int) ds[counterForLeft++];
}else if (counterForRight <len2){
result[resultIndex++] =(int) ds2[counterForRight++];
}
}
return result;
}
private static double[] getIntArray() {
double[] array = new double[10000];
Random random = new Random();
for(int i = 0; i < 10000; i++) {
array[i] = (random.nextDouble() * .99999);
}
return array;
}
}

Answer 1

In the merge method, when copying from one of the input arrays to the results, you cast to int. For example:
result[resultIndex++] =(int) ds[counterForLeft++];
All your doubles are in the range [0...1), so the result of casting any of them to int is zero. Just get rid of those casts, and you will keep your numbers in the merge result.
As an additional tip, it is much easier to debug small problems than large ones. It failed for any size greater than 2, so you should have been debugging with size 2, not 10000.