java - Java中使用LinkedHashMap替换StringBuilder中的字符

Question

基本上，我正在编写一个程序，该程序接受一大块文本(如一篇文章)，并根据其他两个字符串行替换字符，这两个字符串行被纳入程序中，如下所示:

uvxftkbsqpznlcwdeijhoamgyr

etaoinsrhldcumfpgwybvkxjqz

程序迭代大文本 block 中的字符，如果某个字符与顶行字符匹配，则将其替换为下面的字符。 我已将两个字符串行放入 LinkedHashMap 中以便于访问，但由于某种原因，程序无法正确替换字符。这是我的代码:

public class MyReplacer{

public static void main(String[] args) throws IOException {
    String fileName = "";
    Scanner in = new Scanner(System.in);
    System.out.println("Please enter file name");
    fileName = in.nextLine();
    BufferedReader readerForText = new BufferedReader(new FileReader(fileName));
    Scanner keyFileReader = new Scanner(new File("Key.txt"));
    String topLine = "";
    String bottomLine = "";
    //BufferedReader readerForKeyFile = new BufferedReader(new FileReader("Key.java"));
    StringBuilder fileString = new StringBuilder();

    List<Character> topList = new ArrayList<Character>();

    List<Character> bottomList = new ArrayList<Character>();

    try{
         String line = readerForText.readLine();
         while (line!= null){
             fileString.append(line);
             fileString.append("\n");
             line = readerForText.readLine();
         }
         fileString.toString().toLowerCase();

         System.out.println(fileString);
         topLine = keyFileReader.nextLine();
         bottomLine = keyFileReader.nextLine();


         //Convert top line to char array
         char arrayChar1[] = topLine.toCharArray();
         for(char a:arrayChar1)
         {
            topList.add(a);
         }

         //Convert bottom to char array
         char arrayChar2[] = bottomLine.toCharArray();
         for(char a:arrayChar2)
         {
            bottomList.add(a);
         }


         LinkedHashMap<Character,Character> keyMapper = new LinkedHashMap<Character,Character>();

         for(int i = 0;i<topLine.length();++i)
         {
             keyMapper.put(arrayChar1[i],arrayChar2[i]);
         }

         //Testing that key and value pair has been read in correctly
             for(Map.Entry<Character, Character> entry : keyMapper.entrySet())
                {
                    System.out.print(entry.getKey()+  "\n" + entry.getValue());
                }


         //Replace letters in fileString

            for(int x = 0;x<fileString.length();x++)
            {
                for(Map.Entry<Character, Character> entry : keyMapper.entrySet())
                {
                    if(fileString.charAt(x)==entry.getKey())
                    {
                        fileString.setCharAt(x,entry.getValue());
                    }

                }
            }
System.out.println(fileString);



     } finally{
         readerForText.close();
         keyFileReader.close();
 }
}

大文本的示例如下所示:

vkpuu mlusvbxfs

但是，当我替换角色时，它看起来像:

wxujj xujzwzkvz

因此它没有正确替换字符

任何关于为什么这样做的解释都会很棒。 谢谢

Answer 1

问题就出在这里。

for(int x = 0;x<fileString.length();x++)
{
    for(Map.Entry<Character, Character> entry : keyMapper.entrySet())
    {
        if(fileString.charAt(x)==entry.getKey())
        {
            fileString.setCharAt(x,entry.getValue());
        }

    }
}      

这应该是

for(int x = 0;x<fileString.length();x++)
{
    Character c = keyMapper.get(fileString.charAt(x));
    if (c != null)
        fileString.setCharAt(x, c);
}

您的方法的问题在于，通过搜索这样的条目，您可以多次更改单个字符。

例如

u -> e -> g -> j