問題在Java中

Question

替換字符串我試圖用一個縮短的URL替換字符串內的URL：

public void shortenMessage() 
    { 
     String body = composeEditText.getText().toString(); 
     String shortenedBody = new String(); 
     String [] tokens = body.split("\\s"); 

     // Attempt to convert each item into an URL. 
     for(String token : tokens) 
     { 
      try 
      { 
       Url url = as("mycompany", "someapikey").call(shorten(token)); 
       Log.d("SHORTENED", token + " was shortened!"); 
       shortenedBody = body.replace(token, url.getShortUrl()); 
      } 
      catch(BitlyException e) 
      { 
       //Log.d("BitlyException", token + " could not be shortened!"); 

      } 
     } 

     composeEditText.setText(shortenedBody); 
     // url.getShortUrl() -> http://bit.ly/fB05 
    } 

鏈接之後被縮短，我想打印在一個EditText修改後的字符串。我的EditText沒有正確顯示我的消息。

例如：

"I like www.google.com" should be "I like [some shortened url]" after my code executes. 

Answer 1

在Java中，字符串是不可變的。 String.replace（）返回一個新的字符串，這是替換的結果。因此，當您在循環中執行shortenedBody = body.replace(token, url.getShortUrl());時，shortenedBody將保留（僅最後一次）替換的結果。

這裏有一個修復，使用StringBuilder。

public void shortenMessage() 
{ 
    String body = composeEditText.getText().toString(); 
    StringBuilder shortenedBody = new StringBuilder(); 
    String [] tokens = body.split("\\s"); 

    // Attempt to convert each item into an URL. 
    for(String token : tokens) 
    { 
     try 
     { 
      Url url = as("mycompany", "someapikey").call(shorten(token)); 
      Log.d("SHORTENED", token + " was shortened!"); 
      shortenedBody.append(url.getShortUrl()).append(" "); 
     } 
     catch(BitlyException e) 
     { 
      //Log.d("BitlyException", token + " could not be shortened!"); 

     } 
    } 

    composeEditText.setText(shortenedBody.toString()); 
    // url.getShortUrl() -> http://bit.ly/fB05 
} 

Answer 2

你可能想String.replaceAll和Pattern.quote到「引用」你的字符串，你把它傳遞給的replaceAll，它接受一個正則表達式之前。