Question

只需要这个if(e.getSource() == this.newFile)部分的答案如果textArea包含任何文字，则提示“您要将此文件或 DISCARD 保存到NewFile吗？”

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.MenuShortcut;
import java.awt.TextArea;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.Scanner;

import javax.swing.JFileChooser;
import javax.swing.JFrame;


public class Notepad extends JFrame implements ActionListener {

    private TextArea textArea = new TextArea("",0,0,TextArea.SCROLLBARS_VERTICAL_ONLY);

    private MenuBar menuBar = new MenuBar();
    private Menu File = new Menu();
    private MenuItem newFile = new MenuItem();
    private MenuItem openFile = new MenuItem();
    private MenuItem saveFile = new MenuItem();
    private MenuItem close = new MenuItem();

    Notepad(){
        this.setSize(500,300);
        this.setTitle("Java Notepad");
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        this.textArea.setFont(new Font("Century Gothic", Font.BOLD, 12));
        this.getContentPane().setLayout(new BorderLayout());
        this.getContentPane().add(textArea);

        this.setMenuBar(this.menuBar);
        this.menuBar.add(File);
        this.File.setLabel("File");

        this.newFile.setLabel("New");
        this.newFile.addActionListener(this);
        this.newFile.setShortcut(new MenuShortcut(KeyEvent.VK_N, false));
        this.File.add(this.newFile);


        this.openFile.setLabel("Open    ");
        this.openFile.addActionListener(this);
        this.openFile.setShortcut(new MenuShortcut(KeyEvent.VK_O, false));
        this.File.add(this.openFile);

        this.saveFile.setLabel("Save    ");
        this.saveFile.addActionListener(this);
        this.saveFile.setShortcut(new MenuShortcut(KeyEvent.VK_S, false));
        this.File.add(this.saveFile);

        this.close.setLabel("Close");
        this.close.setShortcut(new MenuShortcut(KeyEvent.VK_F4, false));
        this.close.addActionListener(this);
        this.File.add(this.close);
    }

    public void actionPerformed (ActionEvent e){
        if(e.getSource() == this.close)
            this.dispose();

        else if(e.getSource() == this.openFile){
            JFileChooser open = new JFileChooser();
            int option = open.showOpenDialog(this);

            if(option == JFileChooser.APPROVE_OPTION){
                this.textArea.setText("");

                try{
                    Scanner scan = new Scanner(new FileReader(open.getSelectedFile().getPath()));
                    while(scan.hasNext())
                        this.textArea.append(scan.nextLine()+"\n");
                }
                catch(Exception ex){
                    System.out.println(ex.getMessage());
                }
            }
        }
        else if(e.getSource() == this.saveFile){
            JFileChooser save = new JFileChooser();
            int option = save.showSaveDialog(this);

            if(option == JFileChooser.APPROVE_OPTION){
                try{
                    BufferedWriter out = new BufferedWriter(new FileWriter(save.getSelectedFile().getPath()));
                    out.write(this.textArea.getText());
                    out.close();
                }
                catch(Exception ex){
                    System.out.println(ex.getMessage());
                }
            }
        }
        else if(e.getSource() == this.newFile){

        }
    }

    public static void main(String args[]){
        Notepad app = new Notepad();
        app.setVisible(true);
    }
}

Answer 1

而不是这样做：

this.saveFile.addActionListener(this);

然后这个：

e.getSource() == this.saveFile

你应该这样：

this.saveFile.addActionListener(this);
this.saveFile.setActionCommand("xy");

然后这个：

e.getActionCommand.equals("xy");

要显示提示，您可以使用JOptionPane

Answer 2

如果用户说“是”，希望您需要保存文件。

private String message = "Do u want to save this file ?"

int reply = JOptionPane.showConfirmDialog(null, "message", "title",JOptionPane.YES_NO_OPTION);
if (reply == JOptionPane.YES_OPTION) {
    save(this.textArea.getText(), save.getSelectedFile().getPath()));
}else {
    //what you need
}

private void save(String content, String path) {
        try{
            BufferedWriter out = new  BufferedWriter(newFileWriter(path) );
            out.write(content);
            out.close();
        } catch(Exception ex){
            System.out.println(ex.getMessage());
        }`enter code here`
    }

你也可以在（e.getSource（）== this.saveFile）if else子句上使用save方法。

在记事本程序的文件菜单中包含“新建”

2 个答案: