markdown
#說明
二元搜尋法，是將資料分成兩半，由中間開始搜尋，並且比較大小，太小往大的那邊搜尋、太大往小的那邊搜尋。
#操作流程
##Code
```
import java.io.*;
class Searcher{
int [] data;
int item;
int search(int[] data,int item)
{
this.data=data;
this.item=item;
return BSearch(0,data.length-1);
//test
}
int BSearch(int low ,int high){
if (low> high) {
return -1;
}
int middle=(low + high)/2 ;
if (item ==data[middle]) {
return middle;
}
else if (item>data[middle]) {
return BSearch(middle+1,high);
}
else {
return BSearch(low,middle-1);
}
}
}
public class BSearch {
public static void main(String[] argv)throws IOException {
Searcher a= new Searcher();
System.out.print("please input what you want to find\n->");
BufferedReader br =new
BufferedReader(new InputStreamReader(System.in));
int target =java.lang.Integer.parseInt(br.readLine());
int i =a.search(new int []{3,5,7,8,10,34,56},target);
if (i==-1) {
System.out.println("Didn't find it"+target);
}
else {
System.out.println("in the "+ i +" location find target "+ target );
}
}
}
```
##Demo
- Code
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