简单的java程序

1.二分查找，java的输入与输出

 1 package com;
 2 
 3 
 4 public class Firstapp{
 5     public static void main(String args[])
 6     {
 7         java.util.Scanner sc=new java.util.Scanner(System.in);
 8         int n,start,end,middle;
 9         System.out.println("请输入：");
10         n=sc.nextInt();
11         int a[]={-2,1,4,5,8,12,17,23,45,56,90,100};
12         start=0;
13         end=a.length-1;
14         middle=(start+end)/2;
15         int count=0;
16         while(n!=a[middle]){
17             if(n>a[middle]){
18                 start=middle;
19             }
20             else if(n<a[middle]){
21                 end=middle;
22             }
23                 middle=(start+end)/2;
24                 count++;
25                 if(count>a.length/2)    
26                     break;
27             }
28         if(count>a.length/2)
29             System.out.println(":"+n+"不在数组内");
30         else
31             System.out.println(":"+n+"是数组中第"+middle+"个元素");
32         
33         }
34     }

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