Java基本算法

import java.util.Scanner; 

public class BinarySearch { 

/* 
* 二分查找法 
*/ 
public static int binarySearch(int[] a, int x, int n) { 
int left = 0; 
int right = n - 1; 
while (left <= right) { 
int middle = (left + right) / 2; 
if (x == a[middle]) 
return middle; 
if (x > a[middle]) 
left = middle + 1; 
else 
right = middle - 1; 
} 
return -1; 
} 

public static void main(String[] args) { 
Scanner sc = new Scanner(System.in); 
// 输入数组个数 
System.out.println("请输入数组元素的个数："); 

int idex = sc.nextInt(); 
// 生成数组 
int[] b = new int[idex]; 
// 输入元素 
System.out.println("请输入元素："); 
for (int i = 0; i < b.length; i++) { 
b[i] = sc.nextInt(); 
} 
System.out.println("输入的数组内容为："); 
for (int a : b) { 
System.out.println(a); 
} 
System.out.println("---------------------------"); 
// 排序 
System.out.println("数组进行排序后输出为："); 
b = sort(b); 
for (int a : b) { 
System.out.println(a); 
} 
System.out.println("---------------------------"); 
// 输入要查询的元素 
System.out.println("请输入要查询的元素："); 
int element = sc.nextInt(); 
int i = binarySearch(b, element, b.length); 
     System.out.println(i); 

} 
// 由小到大排序（进行选择排序） 
public static int[] sort(int[] a) { 
for (int i = 0; i < a.length; i++) { 
for (int j = 0; j < a.length - 1; j++) { 
if (a[j] > a[j + 1]) { 
int temp = a[j]; 
a[j] = a[j + 1]; 
a[j + 1] = temp; 
} 
} 
} 
return a; 
} 
}