java - 在子字符串上使用 "Predefined character classes"

Question

我想使用 '\W' 检查字符串的最后一个字符是否为非单词字符，并允许使用某些符号，例如“.，!等”，我想到使用代码与此类似。

Boolean notCompleted = true;
           int deduct = 1;
           while(notCompleted){
               if(string.charAt(string.length() -deduct) == '\W'){ // '\W' <-- doesn't work since it accepts anything other than "escape sequences".
                   if(string.charAt(string.length() -deduct) == '.'||string.charAt(string.length() -deduct) == ','||string.charAt(string.length() -deduct) == '!'){
                       //Do nothing and move on to the while loop
                   }else{
                       //Replace the non word character with ' '.
                   }
               }
               deduct++;
               if(deduct >= html.length()){
                   notCompleted = false;
               }
           }

这不起作用的原因是因为使用 string.charAt 只接受“转义序列”。

My question is there another way to pull this off rather than doing.

string.replaceAll("\W", "");

非常感谢所有建议。谢谢。

感谢 npinti 给我的提示，我构建了这段代码。但是我收到一条错误行

所请求的 fakeNewString 的期望结果应该是“!asdsdefwef.,a,,sda.sd”；

fakeNewString = sb.toString(); // NullPointerException

public static void test5(){
        Boolean notCompleted = true;
        String fakeNewString = "!@#$%^&*( asdsdefwef.,a,,sda.sd";
        int start = 0, end = 1;
           StringBuilder sb = null;
           try{

        while(notCompleted){
               start++;
               String tempString = fakeNewString.substring(start, end);
               if(Pattern.matches("\\W$", tempString)){
                   if(Pattern.matches("!", tempString)||Pattern.matches(".", tempString)||Pattern.matches(",", tempString)||Pattern.matches("\"", tempString)){
                       //do nothing
                       sb.append(tempString);
                   }else{
                       //Change it to spaces.
                       tempString = " ";
                       sb.append(tempString);
                   }
               }
               end++;
               if(end >= fakeNewString.length()){
                   notCompleted = false;
                   fakeNewString = sb.toString();
                   System.out.println(fakeNewString);
               }
           }

       }catch (Exception e) {
        // TODO: handle exception
           e.printStackTrace();
       }
}

Answer 1

你可以这样做:

Pattern pattern = Pattern.compile("\\W$");
Matcher matcher = pattern.match(string);

if (matcher.find())
{
    //do something when the string ends with a non word character
}

看看this有关正则表达式的更多信息的教程。