static int | binarySearch(int[] a, int key) Searches the specified array of ints for the specified value using the binary search algorithm. |
import java.util.Arrays;
public class Test {
public static void main(String[] args) {
// initializing unsorted byte array
byte byteArr[] = {10,20,15,22,35};
// sorting array
Arrays.sort(byteArr);
// let us print all the elements available in list
System.out.println("The sorted byte array is:");
for (byte number : byteArr) {
System.out.println("Number = " + number);
}
// 输入需要搜索的数字
byte searchVa1 = 15; //搜索在数组的数字
byte searchVa2 = 22; //搜索不在数组的数组
int retVa1 = Arrays.binarySearch(byteArr,searchVa1);
int retVa2 = Arrays.binarySearch(byteArr, searchVa2);
int position1=retVa1>=0?retVa1:-retVa1-2;
int position2=retVa2>=0?retVa2:-retVa2-2;
System.out.println("The index of 10 element is : " + position1); //输出结果为 1
System.out.println("The index of 22 element is : " + position2); //输出结果为 3
}
}
15在数组排序后是第2个,索引为1
22在数组排序后在第3个和第4个中间 位置排在第4个,索引为3
需要注意的是,用Arrays.binarySearch搜索时,必须对元素进行排序.