How to have a JButton that moves as I scroll on the frame?

I have a Panel which I have made scrollable in my frame.
What I need is to add a button that stays fixed in the lower right corner even when I scroll.
I'm new to Java Swing so would appreciate all and any help that I can get.

mainPanel = new SimulationPanel(); //class SimulationPanel extends JPanel

//making mainPanel scrollable
mainPanel.setPreferredSize(new Dimension(((int)(WIDTH*1.2)), HEIGHT));
JScrollPane scrollPane = new JScrollPane(mainPanel);
scrollPane.setViewportView(mainPanel);

// Settings for JFrame
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
frame = new JFrame("Warehouse Simulator");
frame.setContentPane(scrollPane);
frame.setSize(screenSize.width, screenSize.height);
frame.setResizable(true);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setVisible(true);

</details>


# 答案1
**得分**: 2

我会使用嵌套的面板，其中外部面板采用 `BorderLayout`。然后使用一个采用 `FlowLayout` 的面板，将其对齐到 `FlowLayout.RIGHT`，并将按钮放在其中。

```java
public class Example extends JFrame {
    public Example() {
        super("");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        setLayout(new BorderLayout());

        JTextArea textArea = new JTextArea(10000, 0);
        JScrollPane scrollPane = new JScrollPane(textArea);

        add(scrollPane, BorderLayout.CENTER);

        JButton button = new JButton("button");

        JPanel panelWithButton = new JPanel(new FlowLayout(FlowLayout.RIGHT));
        panelWithButton.add(button);
        add(panelWithButton, BorderLayout.PAGE_END);

        setLocationByPlatform(true);
        pack();
        setSize(600, 600);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            new Example().setVisible(true);
        });
    }
}

结果：

public class Example extends JFrame {
	public Example() {
		super("");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		setLayout(new BorderLayout());

		JTextArea textArea = new JTextArea(10000, 0);
		JScrollPane scrollPane = new JScrollPane(textArea);

		add(scrollPane, BorderLayout.CENTER);

		JButton button = new JButton("button");

		JPanel panelWithButton = new JPanel(new FlowLayout(FlowLayout.RIGHT));
		panelWithButton.add(button);
		add(panelWithButton, BorderLayout.PAGE_END);

		setLocationByPlatform(true);
		pack();
		setSize(600, 600);
	}

	public static void main(String[] args) {
		SwingUtilities.invokeLater(() -> {
			new Example().setVisible(true);
		});
	}
}

答案2

得分: 1

我会选择使用BoxLayout。在metaPanel中添加另一个面板（scrollingPanel），然后在其中放置你的滚动面板，然后再添加一个按钮。不再使用scrollingPanel作为contentPane，而是使用metaPanel。示例（示例可行，但你需要修改它以使界面看起来更好）：

JPanel mainPanel = new JPanel();
JScrollPane scrollPane = new JScrollPane(mainPanel);
scrollPane.setViewportView(mainPanel);

JPanel metaPanel = new JPanel();
BoxLayout boxlayout = new BoxLayout(metaPanel, BoxLayout.Y_AXIS);
metaPanel.setLayout(boxlayout);
metaPanel.add(scrollPane);
metaPanel.add(new JButton("按钮"));

// JFrame的设置
frame = new JFrame("仓库模拟器");
frame.setContentPane(metaPanel); // 在这里放置metaPanel
frame.setSize(500, 300);
frame.setResizable(true);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setVisible(true);

    JPanel mainPanel = new JPanel();
    JScrollPane scrollPane = new JScrollPane(mainPanel);
    scrollPane.setViewportView(mainPanel);

    JPanel metaPanel = new JPanel();
    BoxLayout boxlayout = new BoxLayout(metaPanel, BoxLayout.Y_AXIS);
    metaPanel.setLayout(boxlayout);
    metaPanel.add(scrollPane);
    metaPanel.add(new JButton("button"));

    // Settings for JFrame
    frame = new JFrame("Warehouse Simulator");
    frame.setContentPane(metaPanel); // Put metaPanel here
    frame.setSize(500, 300);
    frame.setResizable(true);
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.setVisible(true);