废话少说,看代码

public static void main(String[] args) {
            
		//二分查找:有多个相同的值时只查出现的第一个,立刻停止查找
		//查到了返回下标
		//普通查找
		int arr[]={1,2,3,4,5};
		int index = Search(arr, 4);
		System.out.println(index);
			//二分查找
		int arr1[]={1,2,3,4,5,16,28,44,56,66,128};
		int index1=ErFenSearch(arr1, 66);
		System.out.println(index1);
	}
		//普通查找
	public static int Search(int []arr,int key){
		for(int i=0;i<arr.length;i++){
			if(key==arr[i]){
				return i;
			}
		}
		return -1;
	}
	//二分查找
public static int ErFenSearch(int []arr,int key){
         Search(arr,70)
		int max=arr.length -1;
		int min =0;
		while(min<=max){
			int mid =(max+min)/2;	//int mid =(max+min) >>1;
			if(arr[mid] == key){
				return mid;
			}else if(arr[mid]>key){
				max=mid-1;
			}else if(arr[mid]<key){
				min=mid+1;
			}
		}
		return -1;
	}