Question

ActionPerformed方法不允许我抛出IOException，那么在执行某个动作时如何读取.txt文件呢？谢谢你的帮助。

 public void actionPerformed(ActionEvent event) {

 String command = event.getActionCommand();
 if (command.equals("Word puzzle generator")) {
   file=textN.getText()+".txt";
   row=Integer.valueOf(textR.getText());
   col=Integer.valueOf(textC.getText());
   System.out.println(file+row+col);

   readfile(file);



  }
}

Answer 1

你应该不在那里读取文件！

actionPerformed方法由事件派发线程执行。该线程负责更新GUI。当您在此线程中读取文件时，它将阻止用户界面。此类操作应在自己的线程上完成。这可以通过SwingWorker方便地完成，如以下示例所示，该示例读取名为example.txt的文件：

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class ReadFileFromGui
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }

    private static void createAndShowGui()
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton readFileButton = new JButton("Read file");

        readFileButton.addActionListener(e -> readFile());

        f.getContentPane().add(readFileButton);

        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static void readFile()
    {
        SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>()
        {
            @Override
            protected Void doInBackground() throws Exception
            {
                try
                {
                    doReadFile();
                }
                catch (IOException e)
                {
                    JOptionPane.showMessageDialog(
                        null, "Error: "+e.getMessage());
                }
                return null;
            }

            @Override
            protected void done()
            {
                JOptionPane.showMessageDialog(
                    null, "Finished reading file");
            }
        };
        worker.execute();
    }

    private static void doReadFile() throws IOException
    {
        String fileName = "example.txt";
        try (BufferedReader br = new BufferedReader(
            new InputStreamReader(new FileInputStream(fileName))))
        {
            while (true)
            {
                String line = br.readLine();
                if (line == null)
                {
                    break;
                }
                System.out.println("Read: "+line);
            }
        }
    }
}

Answer 2

你需要包装到try-catch块中：

try {
    readfile(file);
}
catch (IOException ex) {
    throw new RuntimeException(ex);
}

如何在actionPerformed中读取文件

2 个答案:

你应该不在那里读取文件！