Java搜索文件

Question

我有两个字符串变量：

"givenAccnt“是从用户获得的输入字符串。

"accntToken“是一行文本的子字符串(第一个字符串)。

如果givenAccnt 等于 accntToken，我希望返回与accntToken匹配的文本行。

此外，可能有超过1匹配的情况。我希望将所有匹配保存到一个变量中，然后立即返回这些匹配(行)。

下面的代码只返回最后一行的匹配。(如果匹配在其他行，它就会错过)

我似乎不明白它为什么会那样做。

任何帮助都将不胜感激。

givenAccnt = searchTextField.getText();//else, user is using search field to get given account
try
   {
      scanner = new Scanner(file);        //initialize scanner on file
      while(scanner.hasNextLine())        //while lines are being scanned
      {   
         getLine = scanner.nextLine();          //gets a line
         int i = getLine.indexOf(' ');          //get first string-aka-accnToken
         accntToken = getLine.substring(0, i);    
       }
       if(givenAccnt.equals(accntToken))   //if match   
       {
          collectedLines = new StringBuilder().append(getLine).toString();
          psswrdLabels = new JLabel(collectedLines, JLabel.LEFT);
          psswrdLabels.setAlignmentX(0);
          psswrdLabels.setAlignmentY(0);
          fndPwrdsCNTR += 1;     //counter for number of passwords found 
          JOptionPane.showMessageDialog(null, psswrdLabels ,+fndPwrdsCNTR+" PASSWORD(S) FOUND!", JOptionPane.INFORMATION_MESSAGE);    //shows window with matched passwords (as JLabels)
                            searchTextField.setText("");    //clears search field, if it was used
         }else
           //..nothing found
     }catch (FileNotFoundException ex) {
         //..problem processing file...
                    } 

Answer 1

不能在每一行上创建新的StringBuilder。相反，在阅读行之前创建它。守则：

givenAccnt = searchTextField.getText();//else, user is using search field to get given account
try
   {
builder=new StringBuilder();//initialize builder to store matched lines
      scanner = new Scanner(file);        //initialize scanner on file
      while(scanner.hasNextLine())        //while lines are being scanned
      {   
         getLine = scanner.nextLine();          //gets a line
         int i = getLine.indexOf(' ');          //get first string-aka-accnToken
         accntToken = getLine.substring(0, i);    
       }
       if(givenAccnt.equals(accntToken))   //if match   
       {
          collectedLines = builder.append(getLine).toString();
          psswrdLabels = new JLabel(collectedLines, JLabel.LEFT);
          psswrdLabels.setAlignmentX(0);
          psswrdLabels.setAlignmentY(0);
          fndPwrdsCNTR += 1;     //counter for number of passwords found 
          JOptionPane.showMessageDialog(null, psswrdLabels ,+fndPwrdsCNTR+" PASSWORD(S) FOUND!", JOptionPane.INFORMATION_MESSAGE);    //shows window with matched passwords (as JLabels)
                            searchTextField.setText("");    //clears search field, if it was used
         }else
           //..nothing found
     }catch (FileNotFoundException ex) {
         //..problem processing file...
                    }