I have a problem. Now I'm working with 3 panels, mainPanel and 2 others ( btnPanel and iconPanel).
So the problem is when I push button "reset" I delete iconPanel and add it again it moves slightly to right on its own. Maybe someone can check my code where the problem?
Also I dont want to create another question so I give 2 extra questions.
Do I delete JPanel properly?
If I delete JPanel with components inside they also will be removed from memory?
P.s. Im beginner so dont judge me :)
Main.java
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Main extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("Made by Mac4s");
frame.setVisible(true);
frame.setSize(310, 654);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setResizable(false);
MainScreen screenObj = new MainScreen();
screenObj.setPreferredSize(new Dimension(310, 650));
frame.add(screenObj);
}
});
}
}
MainScreen.java
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 MainScreen extends JPanel {
private JButton resetBtn;
private JPanel btnPanel;
private JPanel iconPanel;
public MainScreen() {
JPanel mainPanel = new JPanel(new BorderLayout());
this.setBackground(Color.BLACK);
setBtnPanelAndComp();
setIconPanelAndComp();
add(mainPanel);
}
private void setBtnPanelAndComp() {
btnPanel = new JPanel(new BorderLayout());
btnPanel.setBackground(Color.GREEN);
btnPanel.setPreferredSize(new Dimension(295, 30));
setButtons();
this.add(btnPanel, BorderLayout.NORTH);
}
private void setButtons() {
resetBtn = new JButton("Reset");
resetBtn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
resetIconLabel();
}
});
btnPanel.add(resetBtn, BorderLayout.WEST);
}
private void resetIconLabel() {
this.remove(iconPanel);
this.repaint();
this.revalidate();
setIconPanelAndComp();
}
private void setIconPanelAndComp() {
iconPanel = new JPanel(new BorderLayout());
iconPanel.setBackground(Color.YELLOW);
iconPanel.setPreferredSize(new Dimension(295, 580));
this.add(iconPanel, BorderLayout.SOUTH);
}
}
"the problem is when I push button "reset" I delete iconPanel and add it again it moves slightly to right on its own."
The reason this happens is because a JPanel has a FlowLayout by default. You're trying add to a BorderLayout position that is non-existent.
this.add(iconPanel, BorderLayout.SOUTH);
The FlowLayout has default gaps on the edges, so when you set the size of the frame, those gaps aren't respected. To over come this, it is also preferable to pack() the frame, instead of setSize()
The reason BorderLayout works (doesn't shift) is because preferred sizes aren't respected.
If you set the layout in the constructor to this.setLayout(new BorderLayout()); You won't have the shift.
public MainScreen() {
JPanel mainPanel = new JPanel(new BorderLayout());
this.setLayout(new BorderLayout()); <----
setBtnPanelAndComp();
setIconPanelAndComp();
add(mainPanel);
}
Notes
You should setVisible() after adding components. That's why your frame jumps when you first open it. You are setting the frame visible, then moving it around with the location, and adding components.
Related
I am trying to create this layout
for a project using Swing in Java 8, but since Swing is something I have never learned I am really struggling with trying to get the layout set up. I've tried my best but I just do not understand this. I don't think I will have any trouble with the backend functionality of the window I just can't get it to look the way I need it.
A common strategy to solve complex computing tasks, is to break them into small, well defined manageable tasks. Divide and conquer.
This also applies to gui: break the design into small, easy to layout containers.
In this case, consider dividing the design into 4 areas (JPanels) nested in a main JPanel:
This basic layout, that can get you started, can be achieved like so:
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Gui {
private final String text ="Growing ";
private JPanel grid;
private JFrame f;
Gui() {
creategui();
}
void creategui(){
f = new JFrame("Hexagon Cross For Less");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
f.setLayout(new BoxLayout(f.getContentPane(),BoxLayout.Y_AXIS));
JPanel primes = new JPanel();
primes.setPreferredSize(new Dimension(1000,120));
primes.setBackground(Color.CYAN);
f.add(primes);
JPanel xFiles = new JPanel();
xFiles.setPreferredSize(new Dimension(1000,120));
xFiles.setBackground(Color.YELLOW);
f.add(xFiles);
JPanel actions = new JPanel();
actions.setPreferredSize(new Dimension(1000,120));
actions.setBackground(Color.GREEN);
f.add(actions);
JPanel status = new JPanel();
status.setPreferredSize(new Dimension(1000,40));
status.setBackground(Color.LIGHT_GRAY);
f.add(status);
f.pack();
f.setVisible(true);
}
public static void main(String[] args) {
new Gui();
}
}
it produces the following layout:
It can be better structured by representing each such distinct area (JPanel) in a separate class.
The following code produces exactly the same layout (it is a single-file mre. Copy past it to Gui.java and run):
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Gui {
private final String text ="Growing ";
private JPanel grid;
private JFrame f;
Gui() {
creategui();
}
void creategui(){
f = new JFrame("Hexagon Cross For Less");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
f.add(new MainPane());
f.pack();
f.setVisible(true);
}
public static void main(String[] args) {
new Gui();
}
}
class MainPane extends JPanel{
MainPane() {
setLayout(new BoxLayout(this,BoxLayout.Y_AXIS));
add(new Primes());
add(new CrossFiles());
add(new Actions());
add(new Status());
}
}
class Primes extends JPanel{
Primes() {
setPreferredSize(new Dimension(1000,120));
setBackground(Color.CYAN);
}
}
class CrossFiles extends JPanel{
CrossFiles() {
setPreferredSize(new Dimension(1000,120));
setBackground(Color.YELLOW);
}
}
class Actions extends JPanel{
Actions() {
setPreferredSize(new Dimension(1000,120));
setBackground(Color.GREEN);
}
}
class Status extends JPanel{
Status() {
setPreferredSize(new Dimension(1000,40));
setBackground(Color.LIGHT_GRAY);
}
}
To continue, apply the same technique and define the layout of each of the 4 sub panels.
The design of Actions could be :
Hint: Primes and CrossFiles have exactly the same layout.
I am writing some Java code that allows the user to see a frame with JLabel, JTextField and JButton.
I want the JLabel to be called "Count" and I have a problem with FlowLayout.
I want the interface to look like this:
Instead, I have this:
This is my code:
package modul1_Interfate_Grafice;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Exercitiu04 implements ActionListener {
private JFrame frame;
private JLabel labelCount;
private JTextField tfCount;
private JButton buttonCount;
private int count = 0;
public void go() {
frame = new JFrame("Java Counter");
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
frame.getContentPane().add(BorderLayout.CENTER, labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
labelCount.add(tfCount);
buttonCount = new JButton("Count");
labelCount.add(buttonCount);
buttonCount.addActionListener(this);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(350, 150);
frame.setLocation(400, 200);
}
#Override
public void actionPerformed(ActionEvent event) {
count++;
tfCount.setText(count + "");
}
public static void main(String[] args) {
Exercitiu04 a = new Exercitiu04();
a.go();
}
}
Solve it.
Instead of labelCount.setLayout(new FlowLayout());` i should have had
frame.setLayout(new FlowLayout());
From description of JLabel class,
JLabel is:
A display area for a short text string or an image, or both.
But here: labelCount.add(tfCount) and here labelCount.add(buttonCount) you're trying to put a textfield and a button into a label. In this case, positions of button and textfield are controlled by FlowLayout but position of the text in the label is not.
Instead of this, you should put all of your elements in common JPanel, like this:
...
frame = new JFrame("Java Counter");
frame.setLayout(new BorderLayout());
JPanel wrapper = new JPanel(); // JPanel has FlowLayout by default
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
wrapper.add(labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
wrapper.add(tfCount);
buttonCount = new JButton("Count");
buttonCount.addActionListener(this);
wrapper.add(buttonCount);
frame.add(BorderLayout.CENTER, wrapper);
...
And, like MasterBlaster said, you should put swing methods in EDT.
There are only two things you should know about FlowLayout:
a) It is a default layout manager of the JPanel component
b) It is good for nothing.
This trivial layout cannot be achieved with FlowLayout.
When doing layouts in Swing, you should familiarize yourself
with some powerful layout managers. I recommend MigLayout and
GroupLayout.
package com.zetcode;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import net.miginfocom.swing.MigLayout;
/*
Simple UI with a MigLayout manager.
Author Jan Bodnar
Website zetcode.com
*/
public class MigLayoutCounterEx extends JFrame {
public MigLayoutCounterEx() {
initUI();
}
private void initUI() {
JLabel lbl = new JLabel("Counter");
JTextField field = new JTextField(10);
JButton btn = new JButton("Count");
createLayout(lbl, field, btn);
setTitle("Java Counter");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void createLayout(JComponent... arg) {
setLayout(new MigLayout());
add(arg[0]);
add(arg[1]);
add(arg[2]);
pack();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
MigLayoutCounterEx ex = new MigLayoutCounterEx();
ex.setVisible(true);
});
}
}
The example is trivial. You just put the three components into the
cells.
Screenshot:
You shouldn't use setSize when dealing with FlowLayout. Instead use pack(). It makes the window just about big enough to fit all your components in. That should tidy things up for you
I want to write a simple Swing application with a button and a text field at the bottom. I'm using a JTextField but it is not clickable. I searched on the web and SO, but I could not find a solution. In question How to Set Focus on JTextField?, I found the following :
addWindowListener( new WindowAdapter() {
public void windowOpened( WindowEvent e ){
entry.requestFocus();
}
});
but this does not help. In this other question (How do you set a focus on Textfield in Swing?) I found Component.requestFocus() but this does not work either. I also tried
entry.setFocusable(true);
entry.setEditable(true);
entry.setEnabled(true);
without effects. My code:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class StackSample extends JFrame {
public StackSample() {
initUI();
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void initUI() {
JPanel panel = new JPanel(new BorderLayout());
add(panel, BorderLayout.CENTER);
JPanel bottomPanel = new JPanel(new FlowLayout());
panel.add(bottomPanel, BorderLayout.SOUTH);
JButton buttonDraw = new JButton("Draw");
bottomPanel.add(buttonDraw);
JTextField entry = new JTextField();
bottomPanel.add(entry);
setPreferredSize(new Dimension(250, 150));
setLocationRelativeTo(null);
}
private static final long serialVersionUID = 8359448221778584189L;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
MyApp app = new MyApp();
app.setVisible(true);
}
});
}
}
Your JTextField is clickable. The only problem is that it's too small.
This is because you're using FlowLayout, which will make components as small as possible.
One solution is to simply switch to a layout that allows components to fill as much space as possible, such as BoxLayout:
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel,BoxLayout.X_AXIS));
You haven't specified a size for your JTextField, so it defaults to zero characters wide. Try using the constructor that specifies the number of columns.
Also, what is MyApp? I can't see any evidence that your StackSample is ever created or used.
I want to create a gui, which has on the top two horizontal components(a combobox and a button) and on the bottom I would like to add several components. I created everything like that:
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSeparator;
public class minimumExample extends JFrame {
private JButton addItem;
private JComboBox itemBox;
private String[] itemSelect = { "test1", "test2" };
private JPanel addUpperPane;
private JPanel addLowerPane;
public void createControlPane() {
setLayout(new BorderLayout());
addUpperPane = new JPanel(new BorderLayout(5, 5));
addLowerPane = new JPanel(new GridLayout(0, 1));
addItem = new JButton("Add item");
itemBox = new JComboBox(itemSelect);
addItem.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
getContentPane().setLayout(new GridLayout(0, 1));
if(itemBox.getSelectedItem().toString().equals("test1")) {
addLowerPane.add(new Button("Lolonator"));
validate();
repaint();
}
}
});;
addUpperPane.add(itemBox);
addUpperPane.add(addItem);
addUpperPane.add(new JSeparator(JSeparator.HORIZONTAL));
//put everything together
add(addUpperPane);
add(addLowerPane);
repaint();
}
private void makeLayout() {
setTitle("Test App");
setLayout(new BorderLayout());
setPreferredSize(new Dimension(1000, 500));
createControlPane();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setVisible(true);
}
/**
* starts the GUI
*/
public void start() {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
makeLayout();
}
});
}
public static void main(String[] args) throws IOException {
minimumExample ex = new minimumExample();
ex.start();
}
}
My problem is that nothing gets shown and I also thing that the layouts are not correct. Any recommendations what I should change to fix my problem?
I appreciate your answer!
UPDATE
Here is a simple wireframe of how my gui should look like:
UPDATE 2
Changing everything to:
addUpperPane.add(itemBox, BorderLayout.EAST);
addUpperPane.add(addItem, BorderLayout.WEST);
addUpperPane.add(new JSeparator(JSeparator.HORIZONTAL));
//put everything together
add(addUpperPane, BorderLayout.NORTH);
add(addLowerPane, BorderLayout.SOUTH);
Gives me that:
Any recommendations how to remove the gap?
Since you used BorderLayout you need the specify the location of each component of the layout what you are doing is that you are only adding all the component on the same position of the layout which by default is CENTER.
solution:
addUpperPane.add(itemBox,BorderLayout.EAST);
addUpperPane.add(addItem,BorderLayout.WEST);
addUpperPane.add(new JSeparator(JSeparator.HORIZONTAL));
//put everything together
add(addUpperPane,BorderLayout.NORTH);
add(addLowerPane,BorderLayout.SOUTH);
Also this doesn't make since setLayout(new BorderLayout()); that JFrame's default layout is already BorderLayout so no need to set the layout to it again.
EDIT:
If you want your component to be side by side then FlowLayout is the way to go:
addUpperPane = new JPanel(); //default component of JPanel is FlowLayout
addUpperPane.add(itemBox);
addUpperPane.add(addItemT);
EDIT number 2:
problem:
getContentPane().setLayout(new GridLayout(0, 1)); //remove it
sample:
addItem.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(itemBox.getSelectedItem().toString().equals("test1")) {
addLowerPane.add(new Button("Lolonator"));
revalidate();
}
}
});;
The solution of Rod_Algonquin is right.
If you are going to build more GUI I can recommend MigLayout to you. It helps you to write nice GUIs which less lines of readable code.
Their homepage: http://miglayout.com/
For my homework extra credit I am creating a JTabbedPane and adding two Jpanels. I feel like I am very close, but it still does not compile. When I run it, both JPanels open, but the JTabbedPane does not. I get a lot of Unknown Source errors. I suspect that at this point my issue in in the JPanels themselves because they started out being JFrames and I have tried (unsuccessfully I think) to convert the JFrames to JPanels.
JTabbedPaneAssignment is supposed to create the JTabbedPane and populate the two panes with the apps DayGui on one tab and OfficeAreaCalculator on the other. I only include the JTabbedPaneAssignment and DayGui classes here. I apologize if its too much code, I have trimmed off a lot of what I consider extraneous, but there may still be too much.
Here is the calling class JTabbedPaneAssignment
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class JTabbedPaneAssignment extends JPanel
{
public JTabbedPaneAssignment()
{
//super(new GridLayout(1, 1));
JTabbedPane tabbedPane = new JTabbedPane();
DayGui pnlDay = new DayGui();
OfficeAreaCalculator pnlOffice = new OfficeAreaCalculator ();
this.add(tabbedPane);
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
tabbedPane.add(panel1,"First panel");
tabbedPane.add(panel2,"Second panel");
//JComponent panel1 = makeTextPanel("Pane #1");
panel1.setPreferredSize(new Dimension(300, 150));
tabbedPane.addTab("DayGui", panel1);
tabbedPane.setMnemonicAt(0, KeyEvent.VK_1);
//JComponent panel2 = makeTextPanel("Pane #2");
panel2.setPreferredSize(new Dimension(410, 50));
tabbedPane.addTab("OfficeAreaCalculator", panel2);
tabbedPane.setMnemonicAt(1, KeyEvent.VK_2);
add(tabbedPane);
}
protected JComponent makeTextPanel(String text)
{
JPanel panel = new JPanel(false);
JLabel filler = new JLabel(text);
filler.setHorizontalAlignment(JLabel.CENTER);
panel.setLayout(new GridLayout(1, 1));
panel.add(filler);
return panel;
}
// Create JTabbedPane
private static void createAndShowGUI()
{
// Create and set up the window.
JFrame frame = new JFrame("JTabbedPane");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JTabbedPaneAssignment(), BorderLayout.CENTER);
JTabbedPane DayGui = new JTabbedPane();
JTabbedPane OfficeAreaCalculator = new JTabbedPane();
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
Here is DayGui class. It started out as a JFrame, but I am trying to convert it to a JPanel. I think my issue is in this section of code, but I don't know
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//public class DayGui extends JPanel
public class DayGui extends JPanel
{
private JPanel dayPanel;
private JButton cmdGood;
private JButton cmdBad;
public DayGui()
{
//dayPanel = new JPanel("Messages");
cmdGood = new JButton("Good");
cmdBad = new JButton("Bad");
Container c = dayPanel.getRootPane();
c.setLayout(new FlowLayout());
c.add(cmdGood);
c.add(cmdBad);
dayPanel.setSize(300, 150);
ButtonsHandler bhandler = new ButtonsHandler();
cmdGood.addActionListener(bhandler);
cmdBad.addActionListener(bhandler);
dayPanel.setVisible(true);
dayPanel.getRootPane().setBackground(Color.CYAN);
}
class ButtonsHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == cmdGood)
JOptionPane.showMessageDialog(null, "Today is a good day!",
"Event Handler Message",
JOptionPane.INFORMATION_MESSAGE);
if (e.getSource() == cmdBad)
JOptionPane.showMessageDialog(null, "Today is a bad day!",
"Event Handler Message",
JOptionPane.INFORMATION_MESSAGE);
}
}
}
You have been very ambiguous with your question, and you've posted way more code than anyone here has time to trawl through.
I've made a very small but working JTabbedPane example for you to see the smallest amount of work you need to get it working.
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
public class JTabbedPaneExample extends JFrame{
public JTabbedPaneExample(String title){
super(title);
setSize(800,600);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
JTabbedPane tabbedPane = new JTabbedPane();
JPanel panelOne = new JPanel();
JPanel panelTwo = new JPanel();
tabbedPane.add(panelOne,"First panel");
tabbedPane.add(panelTwo,"Second panel");
add(tabbedPane);
}
public static void main(String[] args){
new JTabbedPaneExample("JTP Example").setVisible(true);
}
}
Then running, this code looks like:
If you repeat the same process in your code, and you've still got errors, then the problem is not with your JTabbedPane, but something else.
Okay, here goes a second time. Now you've got the DayGui class up, we notice that you're trying to use dayPanel before you've initialised it. i.e. nowhere do you say dayPanel = new JPanel();. This resulted in a NullPointerException being thrown in your code, screwing up your normal course of exection. Fix this and your DayGui class would run fine at runtime.
Among your codebase, you also do some very funky things, namely start using something but never getting around to finishing it up. An example of this is you extending JPanel, but resorting to using a member variable of type JPanel to do the rest of the work. The suggestion is to scrap the instance variable all together and use the methods you've inherited from extending JPanel.
Now lets move onto your JTabbedPaneAssignment class. Although not terrible, the code is not very readable and it repeats itself in many places (adding your tabbedpanel multiple times). If you were to take this code further into a larger project, maintenance and debugging would quickly become a problem.
For the purposes of showing you how much clutter you had in your code, I've quickly rewritten your provided code to be compilable, and should roughly do what you're working on.
JTabbedPaneAssignment:
import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
public class JTabbedPaneAssignment extends JPanel
{
public JTabbedPaneAssignment()
{
final JTabbedPane tabbedPane = new JTabbedPane();
final DayPanel dayPanel = new DayPanel();
final JPanel officePanel = new JPanel();
tabbedPane.add("DayGui", dayPanel);
tabbedPane.setMnemonicAt(0, KeyEvent.VK_1);
tabbedPane.add("OfficeAreaCalculator", officePanel);
tabbedPane.setMnemonicAt(1, KeyEvent.VK_2);
add(tabbedPane);
}
// Create JTabbedPane
private static void createAndShowGUI()
{
// Create and set up the window.
JFrame frame = new JFrame("JTabbedPane");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JTabbedPaneAssignment(), BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
DayGui - renamed as DayPanel:
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class DayPanel extends JPanel {
public DayPanel() {
super();
setBackground(Color.CYAN);
final JButton goodButton = new JButton("Good");
final JButton badButton = new JButton("Bad");
ActionListener listener = new DayPanel.ButtonsHandler();
goodButton.addActionListener(listener);
badButton.addActionListener(listener);
add(goodButton);
add(badButton);
}
class ButtonsHandler implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
final String command = ((JButton) e.getSource()).getActionCommand();
if (command.equals("Good")) {
showMessage("Today is a good day!");
} else if (command.equals("Bad")) {
showMessage("Today is a bad day!");
}
}
// Show popup message
private void showMessage(String message) {
JOptionPane.showMessageDialog(null, message,
"Event Handler Message", JOptionPane.INFORMATION_MESSAGE);
}
}
}
So what is different in these? Basically, I've removed your NullPointerException you were getting in DayGui. Any other changes I've made are with the intention than you try and keep your code clutter free, so you really know what is going on in your code.
Hope this helps.
When I run it, both JPanels open, but the JTabbedPane does not. I get
a lot of Unknown Source errors.
Well, based on your code and your import section:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
This lines won't compile (unless DayGUI and OfficeAreaCalculator classes are in the same package than your JTabbedPaneAssignment class):
DayGui pnlDay = new DayGui();
OfficeAreaCalculator pnlOffice = new OfficeAreaCalculator ();
This is the only error I've got trying to compile and run your example. I changed lines below:
tabbedPane.addTab( "DayGui", new JPanel());
tabbedPane.addTab("Office Calculator", new JPanel());
And it worked like a charm.
Update
Based on your recent edit (adding your DayGui class, thank you) you have couple of mistakes in your code.
DayGui : this class extends of JPanel so you need to add your components directly on this class, you don't need this panel:
private JPanel dayPanel;
You need to set the layout manager, buttons and background directly on DayGuiclass, like this:
public DayGui() {
cmdGood = new JButton("Good");
cmdBad = new JButton("Bad");
setLayout(new FlowLayout());
add(cmdGood);
add(cmdBad);
setSize(300, 150);
ButtonsHandler bhandler = new ButtonsHandler();
cmdGood.addActionListener(bhandler);
cmdBad.addActionListener(bhandler);
setBackground(Color.CYAN);
}
JTabbedPaneAssignment : I think you're trying to add panel1 and panel2 as tabs but you use add method instead addTab:
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
tabbedPane.add(panel1,"First panel");
tabbedPane.add(panel2,"Second panel");
Also this line:
tabbedPane.addTab("DayGui", panel1);
Should be:
tabbedPane.addTab("DayGui", pnlDay);
Finally in this line you are adding panel2 for a second time and that's not correct:
tabbedPane.addTab("OfficeAreaCalculator", panel2); //I'd comment this line
If you make suggested changes you'll see something like this (BTW the CYAN color almost made me blind :P):
Hope this be helpful and sorry for the extension.