gotodlg.java

一个记事本程序

package notepad;
import javax.swing.*;
import javax.swing.event.*;

import java.awt.*;
import java.awt.event.*;
public class GoToDlg extends JDialog implements ActionListener,DocumentListener{
	JLabel label;
	JTextField tfLine;
	JButton btnOK,btnCancel;
	JPanel panel1,panel2;
	NotePad notePad;
	int line;
	public GoToDlg(NotePad initNotePad){
		setTitle("转到下列行");
		notePad = initNotePad;
		panel1 = new JPanel();
		panel2 = new JPanel();
		tfLine = new JTextField(20);
		tfLine.getDocument().addDocumentListener(this);
		label = new JLabel("请输入行数(L):");
		btnOK = new JButton("确定");
		btnOK.setEnabled(false);
		btnCancel = new JButton("取消");
		btnOK.addActionListener(this);
		btnCancel.addActionListener(this);
		panel1.add(label);
		panel1.add(tfLine);
		panel2.add(btnOK);
		panel2.add(btnCancel);
		
		add(panel1,BorderLayout.CENTER);
		add(panel2,BorderLayout.SOUTH);
		
		setSize(350,100);
		setVisible(false);
	}
	
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
		if(e.getSource() == btnOK){
			try{
				line = Integer.parseInt(tfLine.getText());
			}catch(Exception ee){
				JOptionPane.showMessageDialog(null, "您必须键入一个整数 !!");
				return;
			}
			if(!notePad.goTo(line)){
				JOptionPane.showMessageDialog(null, "行数超过限制 !!");
				return;
			}
			this.setVisible(false);
			this.dispose();
		}
		else if(e.getSource() == btnCancel){
			this.setVisible(false);
			this.dispose();
		}
	}

	public void changedUpdate(DocumentEvent e) {
		// TODO Auto-generated method stub
	}

	public void insertUpdate(DocumentEvent e) {
		// TODO Auto-generated method stub
		int length = tfLine.getText().length();
		if (length > 0) {
			btnOK.setEnabled(true);
		} else {
			btnOK.setEnabled(false);
		}
		try{
			line = Integer.parseInt(tfLine.getText());
		}catch(Exception ee){
			JOptionPane.showMessageDialog(null, "您必须键入一个整数 !!");
		}
	}

	public void removeUpdate(DocumentEvent e) {
		// TODO Auto-generated method stub
		int length = tfLine.getText().length();
		if (length > 0) {
			btnOK.setEnabled(true);
		} else {
			btnOK.setEnabled(false);
		}
	}

}