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External JPanel classs does not show correctly in Main JFrame class

basically I'm trying to understand Threads in Java.So I thought I'd create a main JFrame class containing two JPanels from external classes and then do something in one and control it with messages from the second panel.So far I have only created the first external panel and there the probleme starts! It does not show correctly although it appears to be "loaded".(see system.out lines)
So here is the Main Class
package com.maybee.gui;
import java.awt.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
public class Maybee extends JFrame implements Runnable
{
public JFrame maynFrame = null;
public JPanel contentPanel = null;
public SimPanel simPanel = null;
public int screenWidth = 0;
public int screenHeight = 0;
public Maybee()
{
}
private void init()
{
System.out.println("In Inint");
maynFrame = new JFrame("Maybee");
maynFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice();
screenWidth = gd.getDisplayMode().getWidth();
screenHeight = gd.getDisplayMode().getHeight();
maynFrame.setPreferredSize(new Dimension(screenWidth,screenHeight - 100));
maynFrame.setContentPane(getContentPanel());
maynFrame.setVisible(true);
maynFrame.pack();
}
public JPanel getContentPanel()
{
if (contentPanel == null)
{
contentPanel = new JPanel();
contentPanel.setPreferredSize(new Dimension(screenWidth,screenHeight - 100));
contentPanel.setBorder(new LineBorder(Color.BLUE));
contentPanel.setBackground(Color.RED);
contentPanel.setLayout(new BorderLayout());
contentPanel.add(getSimPanel(),BorderLayout.CENTER);
}
return contentPanel;
}
public SimPanel getSimPanel()
{
if(simPanel == null)
{
simPanel = new SimPanel(this);
}
return simPanel;
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
System.out.println("Start");
Maybee maybee = new Maybee();
maybee.run();
}
});
}
public void run()
{
init();
}
}
and now the first external JPanel class
package com.maybee.gui;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;
public class SimPanel extends JPanel
{
public Maybee localMaybee = null;
public JPanel simPanel = null;
private JButton btn;
public SimPanel(Maybee interMaybee)
{
localMaybee = interMaybee;
init();
}
public void init()
{
simPanel = new JPanel();
simPanel.setLayout(new BorderLayout());
simPanel.setPreferredSize(new Dimension(localMaybee.screenWidth/4,localMaybee.screenHeight - 100));
simPanel.setBackground(Color.GREEN);
simPanel.add(getBtn(),BorderLayout.CENTER);
simPanel.setVisible(true);
System.out.println("IN SIM" + localMaybee.screenWidth);
}
public JButton getBtn()
{
if(btn == null)
{
btn = new JButton("ENDE");
btn.setSize(70, 20);
btn.setForeground(Color.YELLOW);
btn.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
}
});
}
return btn;
}
}
So what am I missing?
Many thanks!

The immediate issue is the second instance of JPanel created in SimPanel.init(). SimPanel is already a JPanel, there is no need to maintain public JPanel simPanel member.
The same problem is in the Maybee class which extends JFrame, but maintains public JFrame maynFrame member.
Also, as already mentioned in comments above (thanks #Frakcool!) :
Make sure to call pack() before setVisible();
Don't call setPreferredSize(), do override getPreferredSize() intead;
No need to extend JFrame;
No need to call setVisible on JPanel;
Don't call btn.setSize(), it is a job for a layout manager;
No need for setContentPane(), JFrame by default has a JPanel as content pane with BorderLayout. Calling add() is enough in this case.
Here is a slightly modified version of the original code (simplified for clarity):
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Maybee2 {
static class SimPanel extends JPanel {
public SimPanel() {
setLayout(new BorderLayout());
JButton btn = new JButton("ENDE");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
//TODO
}
});
add(btn, BorderLayout.CENTER);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 200);
}
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame("Maybee");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
SimPanel simPanel = new SimPanel();
frame.add(simPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
EDIT:
The application may consist of many panels. The high level container such as JFrame is not aware of all the underlying layout complexities and cannot enforce a certain size. The panel itself knows its internal layout and its content. So the panel reports its preferred size to the layout manager which eventually packs the content. See Laying Out Components Within a Container for more information.
setBackground has its effect although the button occupies the center of the BorderLayout which takes all the space of the panel. Change the layout of the panel and see the effect. Or move the button into another area, ie - add(btn, BorderLayout.NORTH); Read more in A Visual Guide to Layout Managers.

JTabbedPane tab border removal

JTabbedPane - tab border is being shown even after using BasicTabbedPaneUI. Please let me know how can I change such that no border is shown between the tabs? Is there any method to remove the border completely ?
Please Send me the code snippet. Thanks in advance.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.basic.BasicTabbedPaneUI;
public class TabbedPaneTest implements Runnable {
#Override
public void run() {
final JTabbedPane pane = new JTabbedPane();
pane.addTab("A", createTab(Color.RED));
pane.addTab("B", createTab(Color.YELLOW));
pane.addTab("C", createTab(Color.BLUE));
pane.setUI(new BasicTabbedPaneUI() {
#Override
protected void paintContentBorder(Graphics g, int tabPlacement, int selectedIndex) {
}
});
pane.setBackground(Color.WHITE);
pane.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent arg0) {
pane.setForegroundAt(pane.getSelectedIndex(), Color.GREEN);
}
});
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(pane);
frame.pack();
//frame.setSize(500, 200);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JPanel createTab(Color color) {
JPanel p = new JPanel(new BorderLayout()) {
private static final long serialVersionUID = 1L;
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 300);
}
};
p.setBorder(BorderFactory.createLineBorder(color, 2));
p.setBackground(Color.WHITE);
return p;
}
public static void main(String[] args) throws Exception {
SwingUtilities.invokeLater(new TabbedPaneTest());
}
}

// Remove the white line under a tab button
Insets insets = UIManager.getInsets("TabbedPane.contentBorderInsets");
insets.top = -1;
UIManager.put("TabbedPane.contentBorderInsets", insets);

How could I make the colour BLACK be transparent on top of the uploaded image?

Right now all I have is created the black background and uploaded my image I wanted. I want to make it so the image is behind a transparent background. I initially had this all in separate class files but put them all in one main class
package Flashlight;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Flashlight3 extends JFrame {
public class FlashLabelChange extends JPanel {
Flashlight.FlashDisp flashDisp;
public FlashLabelChange(Flashlight.FlashDisp _flashDisp) {
flashDisp = _flashDisp;
JButton btn1 = new JButton("Start");
add(btn1);
class Button implements ActionListener {
public void actionPerformed(ActionEvent event) {
if (event.getActionCommand().equals("Start")) {
flashDisp.UpdateLabel("Start");
}
}
}
ActionListener button = new Button();
btn1.addActionListener(button);
}
}
public class FlashDisp extends JPanel {
private JLabel lblName;
private String sLabel;
private JLabel lblImage;
public FlashDisp() {
lblImage = new JLabel();
add(lblImage);
lblName = new JLabel("Start?");
add(lblName); //add it to the Frame
}
void UpdateLabel(String _sNew) {
sLabel = _sNew;
lblName.setText(sLabel);
}
void UpdateBackground(String _sNew) {
sLabel = _sNew;
if (sLabel == ("Black")) {
setBackground(Color.black);
lblImage.setIcon(new ImageIcon("Hallway.png"));
}
}
}
public class FlashColour extends JPanel {
FlashDisp flashDisp;
public FlashColour(FlashDisp _flashDisp) {
flashDisp = _flashDisp;
setLayout(new GridLayout(3, 1));
JButton btnDark = new JButton("Dark");
add(btnDark);
class ColourChangeListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
if (event.getActionCommand().equals("Dark")) {
flashDisp.UpdateBackground("Black");
}
}
}
ActionListener colourChangeListener = new ColourChangeListener();
btnDark.addActionListener(colourChangeListener);
}
}
public static void main(String[] args) {
JFrame frame = new JFrame();
FlashMain flashMain = new FlashMain();
frame.setSize(400, 400);
frame.setTitle("FLAAAASH LIGHT");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(flashMain);
frame.setVisible(true);
}
}

I think that you need to use the opaque method.
Have a look here
setOpaque(true/false); Java for using opaque.
Hope that helps.

Why can this code note be run as a JFrame?

I am trying to make an applet run as a JFrame. The code I have below is simple but should work. It will run as an JApplet but when I go to RUN AS --> nothing appears.
import java.awt.*;
import java.applet.Applet;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class LifeCycle extends Applet
{
private static final long serialVersionUID = 1L;
String output = "test";
String event;
public void init()
{
gui(); //I am not certain if this needs to be there.
event = "\nInitializing...";
printOutput();
}
public void start()
{
event = "\nStarting...";
printOutput();
}
public void stop()
{
event = "\nStopping...";
printOutput();
}
public void destroy()
{
event = "\nDestroying...";
printOutput();
}
private void printOutput()
{
System.out.println(event);
output += event;
repaint();
}
private void gui() {
JFrame f = new JFrame("Not resizable");
JPanel d = new JPanel();
// LifeCycle a = new LifeCycle();
// a.init();//not working
d.setLayout(new BorderLayout());
d.add(new JButton("a"));
d.add(new JButton("b"));
d.setBackground(Color.RED);
//f.add(new LifeCycle());
f.add(d);
f.setSize(545,340);
f.setResizable(false);
f.setLocationRelativeTo(null);
f.setTitle("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//a.destroy();
}
public void paint(Graphics g)
{
System.out.println("Graphics Paint Method!");
g.drawString(output, 100, 100);
}
public static void main(String[] args) {
LifeCycle l = new LifeCycle();
l.gui();
}
}
I would like to see the code that should be changed, but I cannot seem to find why this will not work. I have added to buttons to the panel to be displayed.

Don't mix AWT (Applet) with Swing components. Stick with just Swing.
Gear your class towards creating JPanels. Then you can place it in a JApplet if you want an applet or a JFrame if you want a JFrame.
Read up on use of BorderLayout -- you're adding multiple components to the default BorderLayout.CENTER position, and only one component, the last one added, will show.
For example ...
LifeCycle2.java
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JPanel;
class LifeCycle2 {
private static final int GAP = 5;
private static final int PREF_W = 545;
private static final int PREF_H = 340;
private JPanel mainPanel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return LifeCycle2.this.getPreferredSize();
}
};
public LifeCycle2() {
JPanel buttonPanel = new JPanel(new GridLayout(1, 0, GAP, 0));
buttonPanel.add(new JButton("A"));
buttonPanel.add(new JButton("B"));
buttonPanel.setOpaque(false);
JPanel flowLayoutPanel = new JPanel();
flowLayoutPanel.setOpaque(false);
flowLayoutPanel.add(buttonPanel);
mainPanel.setLayout(new BorderLayout());
mainPanel.setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
mainPanel.setBackground(Color.red);
mainPanel.add(flowLayoutPanel, BorderLayout.NORTH);
}
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
public JComponent getMainPanel() {
return mainPanel;
}
}
Show as a JFrame,
LifeCycleFrame.java
import javax.swing.*;
public class LifeCycleFrame {
private static void createAndShowGui() {
LifeCycle2 lifeCycle2 = new LifeCycle2();
JFrame frame = new JFrame("LifeCycleTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(lifeCycle2.getMainPanel());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Show as an applet,
LifeCycleApplet.java
import java.lang.reflect.InvocationTargetException;
import javax.swing.JApplet;
import javax.swing.SwingUtilities;
public class LifeCycleApplet extends JApplet {
#Override
public void init() {
try {
SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
LifeCycle2 lifeCycle2 = new LifeCycle2();
getContentPane().add(lifeCycle2.getMainPanel());
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
}

Add f.setVisible(true); to the end of the gui() method. Without this call your frame won't be shown.
Please read the "How to Make Frames" Tutorial

how to change UI depending on combo box selection

In dialog I need to display one group of controls if some combo is checked and another group of controls otherwise.
I.e. I need 2 layers and I need to switch between them when combo is checked/unchecked. How can I do that?
Thanks

CardLayout works well for this, as suggested below.
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
/** #see http://stackoverflow.com/questions/6432170 */
public class CardPanel extends JPanel {
private static final Random random = new Random();
private static final JPanel cards = new JPanel(new CardLayout());
private static final JComboBox combo = new JComboBox();
private final String name;
public CardPanel(String name) {
this.name = name;
this.setPreferredSize(new Dimension(320, 240));
this.setBackground(new Color(random.nextInt()));
this.add(new JLabel(name));
}
#Override
public String toString() {
return name;
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
create();
}
});
}
private static void create() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
for (int i = 1; i < 9; i++) {
CardPanel p = new CardPanel("Panel " + String.valueOf(i));
combo.addItem(p);
cards.add(p, p.toString());
}
JPanel control = new JPanel();
combo.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JComboBox jcb = (JComboBox) e.getSource();
CardLayout cl = (CardLayout) cards.getLayout();
cl.show(cards, jcb.getSelectedItem().toString());
}
});
control.add(combo);
f.add(cards, BorderLayout.CENTER);
f.add(control, BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}