尝试将文本文件读入JTextArea

Question

我试图打开一个文本文件并将其值添加到String变量中，然后设置为JTextArea。无论我做什么，它总会在textarea中返回任何内容。 我希望它在您点击清除按钮时更改文本，但是我想将其更改为Test.txt文件中的内容。

package texteditor; 

import java.awt.FlowLayout; 
import java.awt.datatransfer.Clipboard; 
import java.awt.datatransfer.StringSelection; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.io.BufferedReader; 
import java.io.FileNotFoundException; 
import java.io.FileReader; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.io.PrintWriter; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JOptionPane; 
import javax.swing.JTextArea; 

public class GUI extends JFrame { 
    //GUI Variables 

    private JButton save; 
    private JButton clear; 
    private JButton copy; 
    private JButton paste; 
    private JButton open; 
    private JTextArea textField; 
    private StringSelection stringSelection; 
    private Clipboard clipboard; 
    String textFieldWritable; 

    public GUI() { 
     super("Text Editor"); 
     //Sets Layout 
     setLayout(new FlowLayout()); 

     save = new JButton("Save"); 
     add(save); 
     clear = new JButton("Clear"); 
     add(clear); 
     open = new JButton("Open"); 
     add(open); 


     textField = new JTextArea(10, 35); 
     add(textField); 

     handler handle = new handler(); 

     save.addActionListener(handle); 
     clear.addActionListener(handle); 

    } 

    private class handler implements ActionListener { 

     @Override 
     public void actionPerformed(ActionEvent event) { 
      if (event.getSource() == save) { 
       textFieldWritable = String.format("%s", textField.getText()); 
       try { 
        FileWriter fileWrite = new FileWriter("Text.txt"); 
        PrintWriter printWrite = new PrintWriter(fileWrite); 

        printWrite.println(textFieldWritable); 
        printWrite.close(); 
       } catch (IOException e) { 
        JOptionPane.showMessageDialog(null, 
         "Error, File Already Exists!", "Error", 
         JOptionPane.ERROR_MESSAGE); 
       } 
      } else if (event.getSource() == clear) { 
       textField.setText(""); 
      } else if (event.getSource() == open) { 
       try { 
        FileReader fileReader = new FileReader("Text.txt"); 
        BufferedReader bufferedReader = new BufferedReader(fileReader); 

        String inputFile = ""; 
        String textFieldReadable = bufferedReader.readLine(); 

        while (textFieldReadable != null) { 
         inputFile += textFieldReadable; 
         textFieldReadable = bufferedReader.readLine(); 
        } 
        System.out.println("inputFile"); 
       } catch (FileNotFoundException ex) { 
        System.out.println("no such file exists"); 
       } catch (IOException ex) { 
        System.out.println("unkownerror"); 
       } 
      } 
     } 
    } 
} 

Answer 1

对我来说，它看起来像你从来没有把你读过的文字设置到文本区域。

try { 
    FileReader fileReader = new FileReader("Text.txt"); 
    BufferedReader bufferedReader = new BufferedReader(fileReader); 

    String inputFile = ""; 
    String textFieldReadable = bufferedReader.readLine(); 

    while (textFieldReadable != null){ 
     inputFile += textFieldReadable; 
     textFieldReadable = bufferedReader.readLine();      
    } 
    System.out.println("inputFile"); 
    // Opps // 
    textField.setText(inputFile); 

} 
catch (FileNotFoundException ex) { 
    System.out.println("no such file exists"); 
} 
catch (IOException ex) { 
    System.out.println("unkownerror"); 
} 

就个人而言，我只是使用功能通过JTextComponent提供并传递给它一个Reader，并允许它来阅读本身。

import java.awt.BorderLayout; 
import java.awt.EventQueue; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.io.File; 
import java.io.FileReader; 
import java.io.Reader; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextArea; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

public class TextAreaReadTest { 

    public static void main(String[] args) { 
     new TextAreaReadTest(); 
    } 

    public TextAreaReadTest() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
       } 

       JFrame frame = new JFrame("Testing"); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.setLayout(new BorderLayout()); 
       frame.add(new TestPane()); 
       frame.pack(); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 
     }); 
    } 

    public class TestPane extends JPanel { 

     private JTextArea textArea; 

     public TestPane() { 
      setLayout(new BorderLayout()); 
      textArea = new JTextArea(10, 80); 
      add(new JScrollPane(textArea)); 
      JButton read = new JButton("Read"); 
      read.addActionListener(new ActionListener() { 

       @Override 
       public void actionPerformed(ActionEvent e) { 
        Reader reader = null; 
        try { 
         reader = new FileReader(new File("D:/SWANH.txt")); 
         textArea.read(reader, "The force is strong with this one"); 
        } catch (Exception exp) { 
         exp.printStackTrace(); 
        } finally { 
         try { 
          reader.close(); 
         } catch (Exception exp) { 
         } 
        } 
       } 
      }); 
      add(read, BorderLayout.SOUTH); 
     } 

    } 

} 

Answer 2

此代码工作对我来说

public DisplayText() throws IOException { 
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    setBounds(100, 100, 450, 300); 
    contentPane = new JPanel(); 
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 
    setContentPane(contentPane); 
    contentPane.setLayout(null); 

    textArea.setBounds(15, 13, 424, 210); 
    textArea.setEditable(false); 
    contentPane.add(textArea); 

    JScrollPane scrollPane = new JScrollPane(textArea); 
    scrollPane.setBounds(12, 12, 424, 185); 
    contentPane.add(scrollPane); 

    JButton btnPatchDetails = new JButton("Details"); 
    btnPatchDetails.setBounds(135, 234, 137, 25); 
    contentPane.add(btnPatchDetails); 

    btnPatchDetails.addActionListener(this); 
    btnPatchDetails.setActionCommand("Patch Details"); 

    JButton btnNext = new JButton("Next"); 
    btnNext.setBounds(314, 234, 107, 25); 
    contentPane.add(btnNext); 

    JLabel lblDependancyPatchAvailable = new JLabel("Dependancy Patch Available : "); 
    lblDependancyPatchAvailable.setBounds(22, 209, 220, 15); 
    contentPane.add(lblDependancyPatchAvailable); 

    lblAvailability.setBounds(254, 209, 61, 15); 
    contentPane.add(lblAvailability); 
} 

public void actionPerformed(ActionEvent e) { 
    if ("Patch Details".equals(e.getActionCommand())) { 
     BufferedReader reader = null; 
     JarFile jarFile = null; 
     try { 

      String inputFile = "readMe/tempReadme.txt"; 
      String write; 

      jarFile = new JarFile(inputJar); 
       JarEntry entry = jarFile.getJarEntry(inputFile); 

       reader = new BufferedReader(new InputStreamReader(jarFile.getInputStream(entry))); 
       String line,searchStr = "Patch Details",endStr = "Problem:"; 
       boolean readFlag = false; 
       boolean writeFlag = false; 

       while ((line = reader.readLine()) != null) { 

        if (line.trim().contains(searchStr)) { 
         readFlag = true; 
        } 

        if (line.trim().equals(endStr)) { 
         break; 
        } 

        if (readFlag) { 
         StringTokenizer tempTokenizer = new StringTokenizer(line,""); 
         while (tempTokenizer.hasMoreElements()) { 
          write = tempTokenizer.nextToken(); 
         textArea.append(write + "\n"); 
         } 
        } 
        writeFlag = true; 
       } 
       if(writeFlag){ 
        lblAvailability.setText("YES"); 
       } else { 
        lblAvailability.setText(""); 
       } 

       lblAvailability.getText(); 
      } catch (Exception ex) { 
       ex.printStackTrace(); 
      } finally { 

       try { 
        jarFile.close(); 
        reader.close(); 
       } catch (IOException e1) { 
        e1.printStackTrace(); 
       } 
      } 
    }