Java实现折半查找(二分查找)的递归和非递归算法

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*名称:BinarySearch
*功能:实现了折半查找(二分查找)的递归和非递归算法.
*说明:
* 1、要求所查找的数组已有序,并且其中元素已实现Comparable<T>接口,如Integer、String等.
* 2、非递归查找使用search();,递归查找使用searchRecursively();
*
*本程序仅供编程学习参考
*
*@author: Winty
*@date: 2008-8-11
*@email: wintys@gmail.com
*/

class BinarySearch<T extends Comparable<T>> {
private T[] data;//要排序的数据

public BinarySearch(T[] data){
this.data = data;
}

public int search(T key){
int low;
int high;
int mid;

if(data == null)
return -1;

low = 0;
high = data.length - 1;

while(low <= high){
mid = (low + high) / 2;
System.out.println("mid " + mid + " mid value:" + data[mid]);///

if(key.compareTo(data[mid]) < 0){
high = mid - 1;
}else if(key.compareTo(data[mid]) > 0){
low = mid + 1;
}else if(key.compareTo(data[mid]) == 0){
return mid;
}
}

return -1;
}

private int doSearchRecursively(int low , int high , T key){
int mid;
int result;

if(low <= high){
mid = (low + high) / 2;
result = key.compareTo(data[mid]);
System.out.println("mid " + mid + " mid value:" + data[mid]);///

if(result < 0){
return doSearchRecursively(low , mid - 1 , key);
}else if(result > 0){
return doSearchRecursively(mid + 1 , high , key);
}else if(result == 0){
return mid;
}
}

return -1;
}

public int searchRecursively(T key){
if(data ==null)return -1;

return doSearchRecursively(0 , data.length - 1 , key);
}

public static void main(String[] args){
Integer[] data = {1 ,4 ,5 ,8 ,15 ,33 ,48 ,77 ,96};
BinarySearch<Integer> binSearch = new BinarySearch<Integer>(data);
//System.out.println("Key index:" + binSearch.search(33) );

System.out.println("Key index:" + binSearch.searchRecursively(3) );

//String [] dataStr = {"A" ,"C" ,"F" ,"J" ,"L" ,"N" ,"T"};
//BinarySearch<String> binSearch = new BinarySearch<String>(dataStr);
//System.out.println("Key index:" + binSearch.search("A") );
}
}