Layout problem

[Hui Zhao]

Hi, I want to plot a 3d and two combox, but only combox displayed.
Why my drawing no appearence?
Thanks, this is an executable code.

import java.io.*;
 
import java.awt.Font;
import java.awt.Color;
import java.awt.Graphics;
 
import java.awt.geom.*;
 
import java.awt.*;
import java.awt.BorderLayout;
import javax.swing.*;
 
import java.util.Hashtable;
import java.awt.event.*;
import javax.swing.event.*;
import java.applet.Applet;
public class TestLayout extends JApplet
{
private Drawing drawing;
       
        private JComboBox comb;
        private JComboBox alfa;
private Container panel;
        private String af[] = {"Paint","No Paint"};
        private String e[] = {"One","Two"};
        private GridBagLayout layout;
        private GridBagConstraints gbc;
        
public void init()
{
panel = getContentPane();
                drawing = new Drawing();
                panel.add(drawing,"Center");
                panel.add(getComboPanel(),BorderLayout.EAST);
}
 
        public JPanel getComboPanel() {
          
                comb = new JComboBox(e);
                layout = new GridBagLayout();
                JPanel cPanel = new JPanel(layout);
                
                cPanel.setLayout(layout);
                gbc = new GridBagConstraints();
                addComponent(this,comb,0,0,1,1,GridBagConstraints.NONE, GridBagConstraints.CENTER);
                comb.setEditable(false);
                comb.setForeground (Color.BLUE);
                comb.setBackground (Color.GREEN);
 
                comb.setAlignmentX(Component.LEFT_ALIGNMENT);
               
                alfa = new JComboBox(af);
                addComponent(this,alfa,0,1,1,1,GridBagConstraints.NONE, GridBagConstraints.CENTER);
                alfa.setEditable(false);
                alfa.setForeground(Color.BLUE);
                alfa.setBackground(Color.GREEN);
                alfa.setAlignmentX(Component.LEFT_ALIGNMENT);
                
                 cPanel.add(comb);
                 cPanel.add(alfa);
                 return cPanel;
         }         
        
         private void addComponent(Container container, Component component,
                 int row, int column, int width, int height, int fill, int anchor)
         {
             gbc.gridx = column;
             gbc.gridy = row;
             gbc.gridwidth = width;
             gbc.gridheight = height;
             gbc.fill = fill;
             gbc.anchor = anchor;
             layout.setConstraints(component,gbc);
             container.add(component);
         }
}
 
 class Drawing extends JPanel 
{
       public void paintComponent(Graphics g)
    {
            super.paintComponent( g ); // call superclass's paint method
            this.setBackground( Color.WHITE );
            Graphics2D g2d = (Graphics2D)g; 
            g2d.draw3DRect(3,100,90,55,true);
 }
   // end method paintComponent
 
       public static void main(String[] args)
            {
            JFrame appletFrame = new JFrame("My Applet");
            Applet theApplet = new TestLayout();
            appletFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            appletFrame.setSize(800,800);
            appletFrame.add(theApplet,"Center");
            theApplet.init();
            appletFrame.setVisible(true);
            }
} // end class Drawing

[Ulf Dittmer]

panel.add(drawing,"Center");

This looks a bit odd. Have you tried "panel.add(getComboPanel(), BorderLayout.CENTER)" instead?

You should also set the layout explicitly, like "panel.setLayout(new BorderLayout())".