//方法一
package com.watching.contact;
public class QueryTest2 {
public static void main(String[] args) {
int[] arr = new int[] {1,4,8,9,11,15,18,19,20};
//二分法查找需要数列有序
System.out.println();
int dest = 4 ;//输入你想找到的数;
int head = 0;//首索引;
int end = arr.length - 1;//末索引;
boolean isflag = true;
for(int i = 0;i < arr.length / 2;i++) {
int middle = (head + end) / 2;
if (arr[middle] == dest) {
System.out.println("恭喜你找到了" + dest + "!它在数组的第" + middle + "个位置!");
isflag = false;
break;
}
else if(arr[middle] < dest) {
head = middle + 1;
}
else end = middle - 1;
}
if(isflag == true) {
System.out.println("抱歉,没在数组中找到你想找的数~");
}
}
}
//方法二
```package com.watching.contact;
public class QueryTest2 {
public static void main(String[] args) {
//二分法查找需要数列有序
int[] arr = new int[] {1,2,3,4,5,25,99,574,1000};
int dest = 5;
int head = 0;//首索引
int end = arr.length - 1;//末索引
while(head < end) {
int middle = (head + end) / 2;
if(arr[middle] == dest) {
System.out.println("恭喜你找到了" + dest + "!它在数组的第" + middle + "个位置!");
break;
}
else if(arr[middle] < dest) {
end = middle - 1;
}
else {
head = middle + 1;
}
}
}
}