二分查找（Java）

题目：

编写程序，完成以下功能:

(1)输入5个整数到数组中;

(2)使用冒泡法对5个数按从小到大排序，输出排序后的数组;

(3)输入一个整数X，在数组中用二分法查找X，找到输出X在数组中的下标，找不到输出-1;

Java实现：

package com.company;
import java.util.Scanner;

class BinarySearch{
    public int BSearch(int []arr , int search){
        //冒泡排序
        int count = 0;
        while(count < arr.length){
            for(int i = 0 ; i < arr.length - 1 - count ; i ++){
                int temp = 0;
                if(arr[i] > arr[i+1]){
                    temp = arr[i];
                    arr[i] = arr[i+1];
                    arr[i+1] = temp;
                }
            }
            count ++;
        }

        //打印排序完的数组
        System.out.print("排序后的数组为：");
        for(int i = 0 ; i < arr.length ; i ++){
            System.out.print(arr[i] + " ");
            if(i == arr.length - 1){
                System.out.println();
            }
        }

        //二分查找
        int top = 0;
        int rear = arr.length - 1;
        int mid = (top+rear)/2;

        if(search > arr[arr.length-1] || search < arr[0]){
            return -1;
        }

        while(top <= rear){
            mid = (top + rear) / 2;
            if(arr[mid] > search){
                rear = mid - 1;
            }else if(arr[mid] < search){
                top = mid + 1;
            }else{
                return mid;
            }
        }
        return -1;
    }
}

public class Test4 {
    public static void main(String[] args) {
        int []array = new int[5];
        //数组赋值
        System.out.println("请输入5个整数:");
        Scanner input = new Scanner(System.in);
        for(int i = 0 ; i < 5 ; i ++){
            array[i] = input.nextInt();
        }

        BinarySearch bs = new BinarySearch();
        System.out.println("请输入要查找的数字:");
        int search = input.nextInt();
        System.out.println("你要查找的数字的下标是："+bs.BSearch(array,search));
    }
}