[Java]在数组中查找一个数字并返回其下标值

此代码仅用于数组为非递减序列(二分查找)

public class BinarySearch { public static int binarySearch(int[] array,int target){ int left=0; int right=array.length-1; int mid; while(left<=right){ mid=left+(right-left)/2;//中间位置 if(array[mid]==target){ return mid; }else if(target<array[mid]){//如果目标值小于当前Mid下标位置的值 则在前半区查找 right=mid-1; }else{//反之在后半区查找 left=mid+1; } } return -1; } public static void main(String[] args) { int[] array=new int[] {1,2,3,4,5,6,7}; int needValue=binarySearch(array,4); System.out.println("4所在的下标是"+needValue); } }