Java二分查找

package com.m.demo;

import java.util.Arrays;
import java.util.Scanner;

public class Test4 {

	public static void main(String[] args) {

		int []num= {1,3,4,5,7,8,9};
		int start=0,end=num.length-1;
		System.out.println("请输入你要查找的数");
		Scanner s=new Scanner(System.in);
		int input=s.nextInt();
		while(start<=end) {
			if(num[(start+end)/2]input) {
				end=(start+end)/2-1;
			}else {
				System.out.printf("找到了，位置为%d",(start+end)/2);
				break;
			}
		}
		if(start>end) {
			System.out.println("没有这个数");
		}

	}

}