归并排序（java实现）

import java.util.Arrays;

public class MergeSort {

public static void mergeSort(DataWraper[] data){
System.out.println("开始排序：");
sort(data,0,data.length-1);
}
/*将索引从left到right范围的数组元素进行归并排序
* data 待排序数组
* left 待排序数组的第一个元素索引
* right 待排序数组的最后一个元素索引
*/
private static void sort(DataWraper[] data, int left, int right) {
// TODO Auto-generated method stub
if(left<right){
//找出中间索引
int center=(left+right)/2;
//对左边数组进行递归
sort(data,left,center);
//对右边数组进行递归
sort(data,center+1,right);
//合并
merge(data,left,center,right);

}
}
/*将两个数组进行归并，归并前两个数组已经有序，归并后依然有序
* data 数组对象
* left 左数组的第一个元素的索引
* center 左数组的最后一个元素的索引，center+1是右数组第一个元素的索引
* right 右数组的最后一个元素的索引
*/
private static void merge(DataWraper[] data, int left, int center, int right) {
// TODO Auto-generated method stub
DataWraper [] tmpArr=new DataWraper[data.length];
int mid=center+1;
//third记录中间数组的索引
int third=left;
int tmp=left;
while(left<=center&&mid<=right){
//从两个数组中取出最小的放入中间数组
if(data[left].compareTo(data[mid])<=0){
tmpArr[third++]=data[left++];
}else{
tmpArr[third++]=data[mid++];
}
}
//剩余部分依次放入中间数组
while(mid<=right){
tmpArr[third++]=data[mid++];
}
while(left<=center){
tmpArr[third++]=data[left++];
}
//将中间数组中的内容复制回原数组
while(tmp<=right){
data[tmp]=tmpArr[tmp++];
}
System.out.println(Arrays.toString(data));
}
public static void main(String[] args) {
// TODO Auto-generated method stub
DataWraper [] data={
new DataWraper(21, ""),
new DataWraper(30, ""),
new DataWraper(49, ""),
new DataWraper(30, "*"),
new DataWraper(16, ""),
new DataWraper(9, ""),
new DataWraper(-16, ""),
new DataWraper(10, ""),
new DataWraper(25, ""),
new DataWraper(18, ""),
};
System.out.println("排序之前：\n"+Arrays.toString(data));
mergeSort(data);
System.out.println("排序之后：\n"+Arrays.toString(data));
}

}

排序之前：
[21, 30, 49, 30*, 16, 9, -16, 10, 25, 18]
开始排序：
[21, 30, 49, 30*, 16, 9, -16, 10, 25, 18]
[21, 30, 49, 30*, 16, 9, -16, 10, 25, 18]
[21, 30, 49, 16, 30*, 9, -16, 10, 25, 18]
[16, 21, 30, 30*, 49, 9, -16, 10, 25, 18]
[16, 21, 30, 30*, 49, -16, 9, 10, 25, 18]
[16, 21, 30, 30*, 49, -16, 9, 10, 25, 18]
[16, 21, 30, 30*, 49, -16, 9, 10, 18, 25]
[16, 21, 30, 30*, 49, -16, 9, 10, 18, 25]
[-16, 9, 10, 16, 18, 21, 25, 30, 30*, 49]
排序之后：
[-16, 9, 10, 16, 18, 21, 25, 30, 30*, 49]