package org.joy.mjtreetable;public abstract class MergeSort extends Object {    protected Object           toSort[];    protected Object           swapSpace[];    public void sort(Object array[]) {	if(array != null && array.length > 1)	{	    int             maxLength;  	    maxLength = array.length;	    swapSpace = new Object[maxLength];	    toSort = array;	    this.mergeSort(0, maxLength - 1);	    swapSpace = null;	    toSort = null;	}    }    public abstract int compareElementsAt(int beginLoc, int endLoc);    protected void mergeSort(int begin, int end) {	if(begin != end)	{	    int           mid;	    mid = (begin + end) / 2;	    this.mergeSort(begin, mid);	    this.mergeSort(mid + 1, end);	    this.merge(begin, mid, end);	}    }    protected void merge(int begin, int middle, int end) {	int           firstHalf, secondHalf, count;	firstHalf = count = begin;	secondHalf = middle + 1;	while((firstHalf <= middle) && (secondHalf <= end))	{	    if(this.compareElementsAt(secondHalf, firstHalf) < 0)		swapSpace[count++] = toSort[secondHalf++];	    else		swapSpace[count++] = toSort[firstHalf++];	}	if(firstHalf <= middle)	{	    while(firstHalf <= middle)		swapSpace[count++] = toSort[firstHalf++];	}	else	{	    while(secondHalf <= end)		swapSpace[count++] = toSort[secondHalf++];	}	for(count = begin;count <= end;count++)	    toSort[count] = swapSpace[count];    }}