Question

我正在尝试扫描字符串（用户键入的用户名），以获取特殊字符（！@＃$％^＆amp; * _ |？）。但是我相信indexOf会扫描所有这些字符，而不是仅查找一个字符。继承我的代码：

     System.out.println("Please choose a user name, it must contain a special charcter and can include spaces");
    String user;
    String spe = "[^!@#$%^&*(){}><?~*]"; //Chars i want to be accepted
    user = input.nextLine();
     int signin3 = user.indexOf(spe);
     if (signin3 != 0) { //If there there is a chararacter
       System.out.println("Correct");
     } else //If there is no character
       System.out.print("Thats not correct, maybe try one of these at the end: " + user + "123! or" + user + "abc? or" + user "Honda$" );

我遇到的问题是，当我输入一个特殊字符时，它仍会输出其他内容，只有当我输入所有那些不是我希望它工作的字符时它才有效，任何人都知道如何修复这个？谢谢！

Answer 1

首先如评论中所述，indexOf在找不到它寻找的内容时返回-1，而不是0。

我毫不怀疑你在问这个问题之前并没有真正在线搜索解决方案......但无论如何，我推荐的解决方案是使用匹配器。

    System.out.println("insert username");
    String user;
    Pattern p = Pattern.compile("[^a-z0-9 ]"); //Chars to look for
    Scanner scan = new Scanner(System.in);
    user =scan.nextLine();
    Matcher m = p.matcher(user); //Matching the pattern(what you wanna look for) and the username
    boolean b = m.find();
    if (b==true) { //If there there is a chararacter
       System.out.println("Correct");
     } else //If there is no character
       System.out.print("Thats not correct, maybe try one of these at the end: " + user + "123! or" + user + "abc? or" + user+"Honda$" );

如何使用indexOf（）查看字符串是否包含多个子字符串

1 个答案: