二分查找法(Java)

 代码实现

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

public class HalfLookup {
    public static void main(String[] args) {
        //创建扫描器对象
        Scanner sc = new Scanner(System.in);
        //声明int数组，空间为10
        int[] array = new int[10];
        //分别接受数组下标首部，中间位，尾部
        int left = 0,mid = 0,right = array.length-1;
        //接收下标
        int index = -1;

        //输入数据放入数组中
        System.out.printf("请依次输入%d个数据->->->\n",10);
        for(int i = 0;i < array.length; i++){
            System.out.printf("请输入第%d个数据:",i+1);
            array[i] = sc.nextInt();
        }

        //将数组顺序排序才好二分查找
        Arrays.sort(array);
        //输出数组
        System.out.println("\n数组中数据如下->->->");
        for(int i = 0;i < array.length; i++){
            System.out.print(array[i]+"\t");
        }

        //数组.二分查找
        System.out.println("\n请输入需要查找的值:");
        int result = sc.nextInt();
        while(left <= right){
            mid = (left + right)/2;
            if(result < array[mid]){
                right = mid - 1;
            }
            else {
                if (result > array[mid]) {
                    left = mid + 1;
                } else {
                    index = mid;
                    break;
                }
            }
        }
        if(index >= 0){
            System.out.printf("该%d在数组中的第%d个,索引值为array[%d]\n",result,index+1,index);
        }
        else{
            System.out.printf("很遗憾!%d不在该数组中!",result);
        }
    }
}