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POSorting An Array of Generic Type
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  1. POSorting An Array of Generic Type
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    copied!<p>I am trying to implement Merge Sort algorithm on an array of genetic type. The problem is that the result is incorrect since some elements were set to 0. I suspect that the problem came from the casting I did through out the program, but I do not know exactly why.</p> <p>As you can see in sortUsingMerge(), I casted an array of Object to generic. Also in the IF statement below, I casted the Object element in the array to int to be able to compare 2 elements. My intention is that the sorting algorithm should work for any array of any type, but I just do not want to write the Comparator for each type for now. </p> <pre><code>Input array: 5 1 -2 3 7 8 0 Output: -2 0 1 1 3 7 0 </code></pre> <p>Look like number 5 and 8 were somehow converted to different numbers during the sorting. Can someone show me why? Thanks!</p> <pre><code>Source code: public void sortUsingMerge(){ Object[] array = (E[]) new Object[size]; Object[] helper = (E[]) new Object[size]; mergeSort(array,helper,0,size-1); } public void mergeSort(Object[] array, Object[] helper, int low, int high){ if (low&lt;high){ int mid = (low + high)/2; mergeSort(array,helper,low,mid); //sort left half mergeSort(array,helper,mid+1,high);//sort right half merge(array,helper,low,mid,high); } } public void merge(Object[] array, Object[] helper, int low, int mid, int high){ for (int i=low; i&lt;=high; i++){// copy both parts into helper array helper[i] = array[i]; } int helperLeft = low; int helperRight = mid + 1; int current = low; while (helperLeft &lt;= mid &amp;&amp; helperRight &lt;=high){ if ((int)helper[helperLeft] &lt;= (int)helper[helperRight]){ array[current] = helper[helperLeft]; helperLeft++; } else{ array[current] = helper[helperRight]; helperRight++; } current++; } int remain = mid - helperLeft; for (int i=0; i&lt;remain; i++){ array[current+i] = helper[helperLeft + i]; } } </code></pre>
 

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