java - java中的隐藏标签/面板

Question

基本上，我试图让屏幕底部有 3 个按钮，然后在屏幕中间有一个包含文字的标签。但是，我似乎无法同时在 GUI 中同时拥有按钮和标签。我是一名初学者，对布局了解不多(即使我已经阅读过它们)，因此任何帮助/指导都会有助于解释为什么我看不到标签和按钮。在此处输入代码

    import java.awt.Dimension;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class AWorldPanel implements ActionListener {

    /** Declaring all the menu items within the GUI **/
    private JMenuItem Fileitem1 = new JMenuItem("New configuration");
    private JMenuItem Fileitem2 = new JMenuItem("Open configuration file ");
    private JMenuItem Fileitem3 = new JMenuItem("Save");
    private JMenuItem Fileitem4 = new JMenuItem("Save As");
    private JMenuItem Fileitem5 = new JMenuItem("Exit");
    private JMenuItem Viewitem1 = new JMenuItem("Display configuration");
    private JMenuItem Viewitem2 = new JMenuItem("Edit configuration");
    private JMenuItem Viewitem3 = new JMenuItem("Info about Bugs");
    private JMenuItem Viewitem4 = new JMenuItem("Info about Map");
    private JMenuItem Edititem1 = new JMenuItem("Remove");
    private JMenuItem Edititem2 = new JMenuItem("Add");
    private JMenuItem Simulationitem1 = new JMenuItem("Simulation");
    private JMenuItem Helpitem1 = new JMenuItem("Info about application");
    private JMenuItem Helpitem2 = new JMenuItem("Info about author");
    private JLabel theLabel;
    private JPanel thePanel;
    JButton Run, Pause, Reset;
    JFrame GUI = new JFrame("Graphical User Interface");
    private static AWorld guiworld;

    public AWorldPanel() {
        /** Creating the menu **/
        JMenuBar menubar = new JMenuBar();
        JMenu File = new JMenu("File");
        JMenu View = new JMenu("View");
        JMenu Edit = new JMenu("Edit");
        JMenu Help = new JMenu("Help");

        /** welcome label **/
        theLabel = new JLabel("Hello ", JLabel.CENTER);
        theLabel.setVisible(true);
        theLabel.setVerticalTextPosition(JLabel.TOP);
        theLabel.setHorizontalTextPosition(JLabel.CENTER);

        /** file sub menus **/
        menubar.add(File);
        File.add(Fileitem1);
        File.add(Fileitem2);
        File.add(Fileitem3);
        File.add(Fileitem4);
        File.add(Fileitem5);

        menubar.add(View);
        View.add(Viewitem1);
        View.add(Viewitem2);
        View.add(Viewitem3);
        View.add(Viewitem4);

        menubar.add(Edit);
        Edit.add(Edititem1);
        Edit.add(Edititem2);

        menubar.add(Help);
        Help.add(Helpitem1);
        Help.add(Helpitem2);

        JPanel panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
        panel.setBorder(new EmptyBorder(new Insets(300, 125, 100, 100)));

        Run = new JButton("Run");
        Pause = new JButton("Pause");
        Reset = new JButton("Reset");
        panel.add(Run);
        panel.add(Box.createRigidArea(new Dimension(0, 5)));
        panel.add(Pause);
        panel.add(Box.createRigidArea(new Dimension(0, 5)));
        panel.add(Reset);

        GUI.add(panel);
        GUI.add(theLabel);
        GUI.setJMenuBar(menubar);
    }

    private static void createAndShowGUI() {
        AWorldPanel newworld = new AWorldPanel();

        // Create the container
        JFrame frame = new JFrame("Graphical User Interface");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // changing the menu settings
        newworld.GUI.setLocation(300, 100);
        newworld.GUI.setSize(500, 500);
        newworld.GUI.setVisible(true);// Now the frame will appear on screen
    }

    public static void main(String args[]) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Answer 1

JFrame 的默认布局管理器是 BorderLayout。如果您未指定约束，则该组件将被添加到 BorderLayout.CENTER 中。您无法将多个组件添加到布局中的同一位置。尝试这样的事情:

    GUI.add(panel, BorderLayout.SOUTH);
    GUI.add(theLabel, BorderLayout.CENTER);

此外，还要了解标准 Java 命名约定。您将阅读的每本书、教程或示例都使用这些标准，因此不要制定自己的约定。变量名称不以大写字符开头。