刚学java不久，试着写了个最基础简单的代码，高手大神们，指导指导 *-*

Question

  写了个很简单的验证码的代码，高手大神们看看，指点指点  *-* 谢谢 public static void main(String[] args) { //生成验证码（4位） char[] codes={'3','4','5','6','7','8','a','b','c', 'd','e','f','h','i','j','k','m', 'n','p','q','r','s','t','u','v', 'w','x','y','z','A','B','C','D','E','F', 'G','H','I','J','K','M','N','P','Q','R', 'S','T','U','V','W','X','Y'}; int n=4; char[] ver=new char[n]; int index=0; int i; Random random=new Random(); boolean[] used=new boolean[codes.length]; do{ i=random.nextInt(codes.length); if(used[i]){ continue; } ver[index++]=codes[i]; used[i]=true; }while(index!=ver.length); System.out.println(ver[0]+" "+ver[1] +" "+ver[2]+" "+ver[3]); //获取用户输入 Scanner console=new Scanner(System.in); String input; do{ System.out.print("请输入验证码："); input=console.nextLine(); input=input.trim(); }while(input.length()!=ver.length); char[] inp=input.toCharArray(); //System.out.println(inp); //设置忽略大小写 //char ch; for(i=0;i<ver.length;i++){ if(inp[i]-ver[i]=='A'-'a' || inp[i]-ver[i]=='a'-'A'){ inp[i]=ver[i]; } } System.out.println( Arrays.toString(ver)); System.out.println( Arrays.toString(inp)); String in=new String(inp); String check=new String(ver); if(in.equals(check)){ System.out.println("OK!"); }else{ System.out.println("输入错误！"); } } }