java - 想要我的 JButton 返回上一个文本区域

Question

我正在尝试创建一个 GUI，在程序打开时为您提供提示。我不确定如何添加文本，然后创建允许我转到下一个文本或返回到上一个文本的按钮。我不确定我应该使用什么类型的actionListener。

import java.awt.*;
import javax.swing.*;


public class HelpfulHints extends JFrame{

    private JTextArea area; //This is my textarea to display hints
    private JPanel panel;
    private JButton close, previous, next; //Three buttons to operate program

    public HelpfulHints(){

        super("Tip of the Day");
        setLayout(new BorderLayout());

        panel = new JPanel();
        panel.setLayout(new FlowLayout(FlowLayout.CENTER));

        //Create first button
        close= new JButton("Close");
        add(close);

        //Create second button
        previous = new JButton("Previous");
        add(previous);

        //Create third button
        next = new JButton("Next");
        add(next);

        //Add buttons to panel
        panel.add(close);
        panel.add(previous);
        panel.add(next);

        //Keep buttons to south of panel
        add(panel, BorderLayout.SOUTH);

        //Create ButtonHandler for button event handling
        ButtonHandler handler = new ButtonHandler();
        close.addActionListener(handler);
        previous.addActionListener(handler);
        next.addActionListener(handler);

        //Create the helpful hint area on the screen
        area = new JTextArea();
        area.setEditable(true);
        area.setLayout(new FlowLayout(FlowLayout.CENTER));

        add(area, BorderLayout.CENTER);

        setVisible(true);

    }

    //Inner class for button event handling
    private class ButtonHandler implements ActionListener{

        //handle Button event
        @Override
        public void actionPerformed(ActionEvent e){


        }
    }
}

Answer 1

我已经根据您的需要更新了监听器的内容。

private JTextArea area; //This is my textarea to display hints
private JPanel panel;
private JButton close, previous, next; //Three buttons to operate program
private List<String> tips = new ArrayList<String>();
private int displayedTipIndex = 0;

public HelpfulHints(){
    super("Tip of the Day");
    // set up your tips
    tips.add("First Tip");
    tips.add("Second Tip");
    tips.add("Third Tip");

    // ... your other code stays the same...

    //Create the helpful hint area on the screen
    area = new JTextArea();
    area.setEditable(true);
    area.setLayout(new FlowLayout(FlowLayout.CENTER));
    // set first tip
    area.setText(tips.get(displayedTipIndex));
    add(area, BorderLayout.CENTER);    

    // disable previous button when we start
    previous.setEnabled(false);

    //
    setVisible(true);        
}

//Inner class for button event handling
private class ButtonHandler implements ActionListener{

    //handle Button event
    @Override
    public void actionPerformed(ActionEvent e){
        if(e.getSource()==next){
            displayedTipIndex++;
            area.setText(tips.get(displayedTipIndex));
            // disable the next button if no more tips
            if(displayedTipIndex>=tips.size()-1){
                next.setEnabled(false);
            }
            // re-enable previpous button
            previous.setEnabled(true);
        }
        if(e.getSource()==previous){
            displayedTipIndex--;
            area.setText(tips.get(displayedTipIndex));
            /// disable the previous button if no more tips
            if(displayedTipIndex<0){
                previous.setEnabled(false);
            }
            // re-enable next button
            next.setEnabled(true);
        }
        if(e.getSource()==close){
            System.exit(0);
        }
    }
}