Java中的二进制搜索程序

Question

这是我使用二进制搜索的程序代码：

import java.util.Random;


public class QSrt {

int[] arr = new int[20];

public void addElement() {
    for (int i = 0; i < arr.length; i++) {
        Random rd = new Random();
        arr[i] = rd.nextInt(10);
    }

}
public void sort(){
    for (int i = 0; i < arr.length - 1; i++) {
        for (int j = arr.length - 1; j > i; j--) {
           if(arr[j] < arr[j-1]){
              int t = arr[j];
              arr[j] = arr[j-1];
              arr[j-1] = t;
           }

        }

    }
}

public int binarySearch(int val){
    int first = 0;
    int last = arr.length - 1;
    int index = -1;
    while (first <= last) {
        int middle = (first + last)/2;
        if(arr[middle] == val){
            index = middle;
        }else if(arr[middle] < val){
            first = middle + 1;
        }else{
            last = middle - 1;


        }
    }
    return index;
}

public static void main(String[] args) {
    QSrt arr = new QSrt();
    arr.addElement();
    arr.sort();

    for(int i = 0; i < arr.arr.length;i++){
        System.out.print(arr.arr[i] + " ");
    }
    System.out.println("");
    System.out.println(arr.binarySearch(0));
}

}

但我遇到了一个问题：程序只打印已排序数组的元素，然后它继续运行并且不打印索引

图片如下： enter image description here

Answer 1

一旦获得所需的值，您需要跳出循环

if(arr[middle] == val){
        index = middle;
        return index;    //OR just => return middle;
    }