摆动按钮在执行之前不可见

Question

Is it possible to create a button that won't be seen until the user clicks another button?

My goal is for the button to be invisible by default rather than when its clicked on. Then become visible when another action is performed. The code below is my original attempt at creating this.

public void but_roll1ActionPerformed(java.awt.event.ActionEvent evt) 
{
    if (!bal_but.isEnabled() && !gamble_but.isEnabled()) {
        but_roll1.setVisible(true);
        but_roll1.setEnabled(true);         
        d1 = diceRoll();
        die1_display.setText(String.valueOf(d1));  
        but_roll1.setEnabled(false);
    } else {
        but_roll1.setVisible(false);
    }
}  

Answer 1

Two better strategies:

1. Put the button in a CardLayout with a second blank panel till needed.
2. Make the button disabled until the first button is clicked.

I prefer the 2nd as the 'path of least surprise' for the user. YMMV.

Initial view

View after 'effect' button actioned

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

public class ButtonNotUsableTillAction {

    private JComponent ui = null;

    ButtonNotUsableTillAction() {
        initUI();
    }

    public void initUI() {
        if (ui!=null) return;

        ui = new JPanel(new GridLayout(1, 0, 4, 4));
        ui.setBorder(new EmptyBorder(4,4,4,4));

        // first demo, using card layout
        JPanel cardDemoPanel = new JPanel(new GridLayout(1, 0, 2, 2));
        cardDemoPanel.setBorder(new TitledBorder("Card Layout"));
        ui.add(cardDemoPanel);

        JButton actionCardButton = new JButton("Action");
        cardDemoPanel.add(actionCardButton);

        CardLayout cardLayout = new CardLayout();
        JPanel cardLayoutPanel = new JPanel(cardLayout);
        cardDemoPanel.add(cardLayoutPanel);
        cardLayoutPanel.add(new JPanel(), "panel");
        cardLayoutPanel.add(new JButton("Effect"), "button");
        cardLayout.show(cardLayoutPanel, "panel");

        ActionListener flipCardListener = new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                cardLayout.show(cardLayoutPanel, "button");
            }
        };
        actionCardButton.addActionListener(flipCardListener);

        // first demo, using disabled / enabled
        JPanel enabledDemoPanel = new JPanel(new GridLayout(1, 0, 2, 2));
        enabledDemoPanel.setBorder(new TitledBorder("Enabled"));
        ui.add(enabledDemoPanel);
        JButton actionEnabledButton = new JButton("Action");
        enabledDemoPanel.add(actionEnabledButton);
        JButton effectButton = new JButton("Effect");
        enabledDemoPanel.add(effectButton);
        effectButton.setEnabled(false);
        ActionListener enableComponentListener = new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                effectButton.setEnabled(true);
            }
        };
        actionEnabledButton.addActionListener(enableComponentListener);
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception useDefault) {
                }
                ButtonNotUsableTillAction o = new ButtonNotUsableTillAction();

                JFrame f = new JFrame(o.getClass().getSimpleName());
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                f.setLocationByPlatform(true);

                f.setContentPane(o.getUI());
                f.pack();
                f.setMinimumSize(f.getSize());

                f.setVisible(true);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

Answer 2

如@markspace所述，您需要在将按钮设置为可见后重新验证按钮的容器：

but_roll1.getParent().revalidate();