java不显示按钮和标签

Question

我有点卡住了。我应该显示2个按钮和1个标签，但我的程序没有显示它们。如果你有任何想法，那就太好了。我正在使用eclipse，代码正在编译和运行。这是代码

/** This is the driver class of the program.
 * Here is the main method with the JFrame.
 * class name RunFurniture.class
 * @author Kiril Anastasov
 * @date 18/03/2012
 */
import java.awt.*;
import javax.swing.*;
public class RunRurniture 
{

    /**
     * @param args
     */
    public static void main(String[] args) 
    {

        JFrame application = new JFrame();
        PanelFurniture panel = new PanelFurniture();
        application.add(panel);
        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        application.setSize(600,450);
        application.setLocationByPlatform(true);
        application.setVisible(true);

    }

}

/** Here is the GUI of the program.
 * class name PanelFurniture.class
 * @author Kiril Anastasov
 * @date 18/03/2012
 */
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class PanelFurniture extends JPanel implements ActionListener
{

    JLabel label;
    JButton a,b;
    JPanel centerPanel, eastPanel;

    public void actionPerformed(ActionEvent ae)
    {
        this.setLayout(new BorderLayout());

        centerPanel = new JPanel();
        //centerPanel.setLayout();
        this.add(centerPanel, BorderLayout.CENTER);

        eastPanel = new JPanel(new GridLayout(1,3));
        label = new JLabel();
        b = new JButton("Move");
        eastPanel.add(b);
        eastPanel.add(label);
        a = new JButton("ee");
        eastPanel.add(a);

         //this.add(eastPanel);
        this.add(eastPanel, BorderLayout.EAST);
    }
}

Answer 1

您只在执行操作时将组件添加到面板中，并且您从未将其注册为侦听器，因此它将永远不会显示。而是将它们添加到构造函数/init方法中：

public class PanelFurniture extends JPanel
{

    JLabel label;
    JButton a,b;
    JPanel centerPanel, eastPanel;

    public void init()
    {
        this.setLayout(new BorderLayout());

        centerPanel = new JPanel();
        //centerPanel.setLayout();

        this.add(centerPanel, BorderLayout.CENTER);


        eastPanel = new JPanel(new GridLayout(1,3));

        label = new JLabel();
        b = new JButton("Move");
        eastPanel.add(b);
        eastPanel.add(label);
        a = new JButton("ee");
        eastPanel.add(a);

        this.add(eastPanel, BorderLayout.EAST);
    }
}

并在创建面板后调用init()：

PanelFurniture panel = new PanelFurniture();
panel.init();
application.add(panel);

此外，确保用户界面是EDT上的构造函数：

SwingUtils.invokeLater(new Runnable() {
    @Override
    public void run() {
        JFrame application = new JFrame();
        PanelFurniture panel = new PanelFurniture();
        application.add(panel);
        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        application.setSize(600,450);
        application.setLocationByPlatform(true);
        application.setVisible(true);
    }
});