Java:如何用单个字符替换连续字符？

Question

如何在java中用单个字符替换连续字符？

String fileContent = "def  mnop.UVW";
String oldDelimiters = " .";
String newDelimiter = "!";
for (int i = 0; i < oldDelimiters.length(); i++){
    Character character = oldDelimiters.charAt(i);
    fileContent = fileContent.replace(String.valueOf(character), newDelimiter);
}

当前输出:def!!mnop!UVW

所需输出:def!mnop!UVW

请注意，两个空格被替换为两个感叹号。如何用一个分隔符替换连续的分隔符？

Answer 1

由于您想要匹配旧分隔符中的连续字符，因此正则表达式解决方案在这里似乎不可行。如果它属于旧的分隔符之一，您可以改为逐字符匹配，然后将其设置为新的分隔符，如下所示。

import java.util.*;
public class Main{
    public static void main(String[] args) {
        String fileContent = "def  mnop.UVW";
        String oldDelimiters = " .";

        // add all old delimiters in a set for fast checks
        Set<Character> set = new HashSet<>();
        for(int i=0;i<oldDelimiters.length();++i) set.add(oldDelimiters.charAt(i));

        /* 
           match all consecutive chars at once, check if it belongs to an old delimiter 
           and replace it with the new one
        */

        String newDelimiter = "!";
        StringBuilder res = new StringBuilder("");
        for(int i=0;i<fileContent.length();++i){
            if(set.contains(fileContent.charAt(i))){
                while(i + 1 < fileContent.length() && fileContent.charAt(i) == fileContent.charAt(i+1)) i++;
                res.append(newDelimiter);
            }else{
                res.append(fileContent.charAt(i));        
            }
        }

        System.out.println(res.toString());
    }
}

演示: https://onlinegdb.com/r1BC6qKP8