我正在做一个家庭作业,它有四个文本字段和一个文本区域,以及一个将文本字段和文本区域保存到文本文件的按钮,每行一个元素。然后,一个对话框应该通知用户文件已保存。然后,当对话框关闭时,它应该清空文本字段和文本区域。但是,我在程序中遇到了一些问题。
关于对话框窗口,当我尝试编译时,程序显示以下错误:
emailProg.java:81: error: no suitable method found for showMessageDialog(emailProg.sendAction, String)
JOptionPane.showMessageDialog(this, "Saved");
^
其次,我不确定在关闭对话框后如何清空文本字段和文本区域。我知道可以通过使用以下代码来清空文本字段:
[textfield].setText("");
但我不确定如何在关闭对话框后执行此操作。
这是我的代码:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class emailProg extends JFrame {
private JPanel panNorth;
private JPanel panCenter;
private JPanel panSouth;
private JLabel toLabel;
private JLabel ccLabel;
private JLabel bccLabel;
private JLabel subLabel;
private JLabel msgLabel;
private JTextField toField;
private JTextField ccField;
private JTextField bccField;
private JTextField subField;
private JTextArea msgArea;
private JButton send;
//The Constructor
public emailProg() {
setTitle("Compose Email");
setLayout(new BorderLayout());
panNorth = new JPanel();
panNorth.setLayout(new GridLayout(4, 2));
JLabel toLabel = new JLabel("To:");
panNorth.add(toLabel);
JTextField toField = new JTextField(15);
panNorth.add(toField);
JLabel ccLabel = new JLabel("CC:");
panNorth.add(ccLabel);
JTextField ccField = new JTextField(15);
panNorth.add(ccField);
JLabel bccLabel = new JLabel("Bcc:");
panNorth.add(bccLabel);
JTextField bccField = new JTextField(15);
panNorth.add(bccField);
JLabel subLabel = new JLabel("Subject:");
panNorth.add(subLabel);
JTextField subField = new JTextField(15);
panNorth.add(subField);
add(panNorth, BorderLayout.NORTH);
panCenter = new JPanel();
panCenter.setLayout(new GridLayout(2, 1));
JLabel msgLabel = new JLabel("Message:");
panCenter.add(msgLabel);
JTextArea msgArea = new JTextArea(5, 15);
panCenter.add(msgArea);
add(panCenter, BorderLayout.CENTER);
panSouth = new JPanel();
panSouth.setLayout(new FlowLayout());
JButton send = new JButton("Send");
panSouth.add(send);
add(panSouth, BorderLayout.SOUTH);
send.addActionListener (new sendAction());
}
private class sendAction implements ActionListener {
public void actionPerformed (ActionEvent event) {
try {
PrintWriter outfile = new PrintWriter("email.txt");
outfile.print("To: ");
outfile.println(toField.getText());
outfile.print("CC: ");
outfile.println(ccField.getText());
outfile.print("Bcc: ");
outfile.println(bccField.getText());
outfile.print("Subject: ");
outfile.println(subField.getText());
outfile.print("Message: ");
outfile.println(msgArea.getText());
JOptionPane.showMessageDialog(this, "Saved");
}
catch(FileNotFoundException e) {
System.out.println("File not found.");
}
}
}
public static void main(String[] args) {
emailProg win = new emailProg();
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.pack();
win.setVisible(true);
}
}
感谢您提供的任何帮助。