创建两个 JTextField 其中一个是实际金额，另一个是零金额。两者相加 JTextField 到 JPanel cardlayout只显示 JTextField . 下面是一个演示。

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.ComponentOrientation;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;

public class SwapFlds implements ActionListener {
    private JFrame  frame;
    private JPanel  swapper;

    @Override // java.awt.event.ActionListener
    public void actionPerformed(ActionEvent event) {
        CardLayout cl = (CardLayout) swapper.getLayout();
        cl.next(swapper);
    }

    private JPanel createButton() {
        JButton button = new JButton("Swap");
        button.addActionListener(this);
        JPanel panel = new JPanel();
        panel.add(button);
        return panel;
    }

    private JPanel createSwapper() {
        swapper = new JPanel(new CardLayout());
        JPanel real = new JPanel();
        JTextField realAmount = new JTextField(10);
        realAmount.setText("Real amount");
        real.add(realAmount);
        swapper.add(real, "real");
        JPanel dummy = new JPanel();
        JTextField dummyAmount = new JTextField(10);
        dummyAmount.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
        dummyAmount.setText("0");
        dummy.add(dummyAmount);
        swapper.add(dummy, "dummy");
        return swapper;
    }

    private void showGui() {
        frame = new JFrame();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.add(createSwapper(), BorderLayout.PAGE_START);
        frame.add(createButton(), BorderLayout.PAGE_END);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> new SwapFlds().showGui());
    }
}