Develop Reference

How to make a JButtons appear

I want to make a JButton that lies on the NorthPane of the frame, but when I run the program there's no button. Why does it do that?
I'm using IntelliJ IDEA.
BTW I'm posting this question again, cause the first time I didn't get the desired answer.
Here's my code.
package com.company;
import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;
class Fantasyrpglifesim implements JButton {
Fantasyrpglifesim() {
}
public static void main(String[] args) {
MouseInputAdapter();
//Frame//
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.HIDE_ON_CLOSE);
frame.setSize(1500, 1500);
frame.getContentPane();
frame.setVisible(true);
JPanel mainPanel = new JPanel(new BorderLayout());
JPanel northPanel = new JPanel();
mainPanel.add(northPanel,BorderLayout.NORTH );
//frame.setLayout(new FlowLayout());//
//Buttons//
frame.add(BUTTON);
BUTTON.setText("Age up");
northPanel.add(BUTTON);
northPanel.add(BUTTON1);
BUTTON1.setText("Test");
northPanel.add(BUTTON2);
BUTTON2.setText("Test1");
northPanel.add(BUTTON2);
BUTTON2.setText("Test2");
northPanel.add(BUTTON3);
BUTTON3.setText("Test3");
northPanel.add(BUTTON4);
BUTTON4.setText("Test4");
northPanel.add(BUTTON5);
BUTTON5.setText("Test5");
northPanel.add(BUTTON6);
BUTTON6.setText("Test6");
northPanel.add(BUTTON7);
BUTTON7.setText("Test7");
northPanel.add(BUTTON8);
BUTTON8.setText("Test8");
northPanel.add(BUTTON9);
BUTTON9.setText("Test9");
northPanel.add(BUTTON10);
BUTTON10.setText("Test10");
northPanel.add(BUTTON11);
BUTTON11.setText("Test11");
northPanel.add(BUTTON12);
BUTTON12.setText("Test12");
northPanel.add(BUTTON13);
BUTTON13.setText("Test13");
northPanel.setVisible(true);
//panels//
//mainPanel.add(northPanel, BorderLayout.NORTH);//
}
private static void MouseInputAdapter() {
}
}

to add a JButton you have to create a JButton object and add that to the JPanel.
And you need to define it for EVERY button that you want to have.
anywhere. I'm surprised your compiler isn't flagging that
Anyway what you want should look sth like this
JButton testButton = new JButton("test");
northPanel.add(testButton);

First, I want you to check your compiler and IntelliJ cause they're not working if you can run the code you posted.
You cannot implement a JButton unless you have made an interface yourself.
Cause the JButton is not an interface.
No need to set a BorderLayout for your JPanel. FlowLayout will do the job.
Use a for loop to avoid duplicate code.
Learn how to use Swing components.
import javax.swing.*;
import java.awt.*;
class Fantasyrpglifesim {
private static int count = 1;
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel mainPanel = new JPanel();
JButton age = new JButton("Age up");
mainPanel.add(age);
for (int x=0; x<14;x++){
JButton button = new JButton();
button.setText("Test"+ count++);
mainPanel.add(button);
}
frame.getContentPane().add(BorderLayout.NORTH,mainPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1500, 1500);
frame.setVisible(true);
}
}
Is this your desired output?

Setting compontents in Jpanel

I'm trying to create Pair Game. I have created 2 JPanels: first for game map (100 buttons) and second for statistics. The problem is that i have deployment of timer and counter like on left picture, but i want to have it like on right picture (i edited it in paint). What layout should i use? I tryed many solution but nothing worked for me. Also, if i set null manager JPanel dissapear
public class PairGame extends JFrame implements ActionListener{
JLabel counterLabel, timerLabel;
JMenuBar menuBar;
JMenu file, help;
JMenuItem fileNew, fileExit, helpAbout;
JPanel gamePanel, statisticsPanel;
JToggleButton buttons[];
ArrayList <Integer> values;
int temp=0, counter=0;
void createMenuBar()
{
file = new JMenu("File");
fileNew = new JMenuItem("New");
fileNew.addActionListener(this);
fileNew.setAccelerator(KeyStroke.getKeyStroke("ctrl N"));
fileExit = new JMenuItem("Exit");
fileExit.addActionListener(this);
fileExit.setAccelerator(KeyStroke.getKeyStroke("ctrl Q"));
file.add(fileNew);
file.add(fileExit);
file.setMnemonic('f');
help = new JMenu("Help");
helpAbout = new JMenuItem("About");
helpAbout.addActionListener(this);
helpAbout.setAccelerator(KeyStroke.getKeyStroke("ctrl H"));
help.add(helpAbout);
help.setMnemonic('h');
menuBar = new JMenuBar();
menuBar.add(file);
menuBar.add(help);
setJMenuBar(menuBar);
}
public void createGameMap()
{
gamePanel = new JPanel(new GridLayout(10,10));
values = new ArrayList<Integer>();
for(int i=1; i<=50; i++)
values.add(i);
for(int i=51; i<=100; i++)
values.add(i-50);
Collections.shuffle(values);
buttons = new JToggleButton[100];
for(int i=0; i<100; i++)
{
buttons[i] = new JToggleButton(""+(i+1));
buttons[i].setName(String.valueOf(values.toArray()[i]));
buttons[i].addActionListener(this);
gamePanel.add(buttons[i]);
}
gamePanel.setBounds(0,0,550,400);
add(gamePanel);
}
public void createStatisticsPanel()
{
statisticsPanel = new JPanel();
counterLabel = new JLabel("Counter: "+counter);
timerLabel = new JLabel("Timer: ");
statisticsPanel.add(counterLabel);
statisticsPanel.add(timerLabel);
statisticsPanel.setBounds(0,410,540,400);
add(statisticsPanel);
}
PairGame()
{
setTitle("Pair Game");
setSize(565,600);
setLocation(400,100);
setLayout(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
createMenuBar();
createGameMap();
createStatisticsPanel();
setVisible(true);
}
public static void main(String[] args)
{
new PairGame();
}

There is a whole variety of different layout managers that allow you to place your objects "in regards" to each other.
If you have a look at the second example for BoxLayout from Oracle ... surprise: that panel shows "two elements", the upper one being a left aligned label. Probably exactly what you are looking for.
Alternatively; right the first example for GridLayout has aligned labels, too.

The purpose of my answer is not only to demonstrate a possible solution, using layout managers as GhostCat suggested, but also demonstrated the idea of an MCVE to make it easier help and get help.
Please see comment for explanations:
//post imports
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
public class PairGame extends JFrame {
//removed fields to keep code as short as possible
JLabel counterLabel, timerLabel;
JPanel gamePanel, statisticsPanel;
//menu bar removed to keep the code as short as possible
//void createMenuBar()
public void createGameMap()
{
//simplify as much as possible
gamePanel = new JPanel(new GridLayout(1,1));
JToggleButton button = new JToggleButton("1");
gamePanel.add(button);
//use layout managers is preferred practice over setting bounds
add(gamePanel, BorderLayout.CENTER);
}
public void createStatisticsPanel()
{
counterLabel = new JLabel("Counter: ");
timerLabel = new JLabel("Timer: ");
statisticsPanel = new JPanel();
//use layout managers is preferred practice over setting bounds
//the layout you want can be achieved with various managers
//such as BorderLayout, BoxLayout, Gridlayout
//Implementation of BorderLayout
statisticsPanel.setLayout(new BorderLayout());
statisticsPanel.add(counterLabel, BorderLayout.NORTH);
statisticsPanel.add(timerLabel, BorderLayout.SOUTH);
//to test box layout REPLACE the 3 statements above with
//Implementation of BoxLayout
//BoxLayout boxLayout = new BoxLayout(statisticsPanel,BoxLayout.Y_AXIS);
//statisticsPanel.setLayout(boxLayout);
//statisticsPanel.add(counterLabel);
//statisticsPanel.add(timerLabel);
add(statisticsPanel, BorderLayout.SOUTH);
}
PairGame()
{
setTitle("Pair Game");
setSize(565,600);
setLocation(400,100);
//use layout managers is preferred practice over setting bounds
getContentPane().setLayout(new BorderLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
createGameMap();
createStatisticsPanel();
setVisible(true);
}
public static void main(String[] args)
{
new PairGame();
}
}
Don't hesitate to ask for clarifications as needed.

Java - updating values in JFrame/JLabels

I am a beginner Java-coder and a few days ago I felt confident enough in my skills to start my first "big" project. It was basically a calculator, a GUI(only JFrame, JPanels, JLabels and Buttons) that would display data, accept user input, grab some more data from other classes, then calculate stuff and finally update the GUI with the new JLabel values. However I never managed to get the update part done properly, whenever I would press the 'process'-button it would create a new JFrame with the new values, while the old one was still up.
I tried the obvious stuff (repaint(), revalidate(), etc) but that didn't work at all, then I started to shift things around, put parts of the code into new classes, copied code from the net until it eventually worked. However the code was a total mess and I didn't even really understand what went exactly wrong in the first place, so I trashed the entire thing.
Here is a very simplified version of my code before things went downhill:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test_1 extends JFrame {
public static class clicks{
static int clicks = 0;
public int getclicks(){
return clicks;
}
public void setclicks(){
clicks = clicks+1;
}
}
public Test_1(){
clicks getNumber = new clicks();
int x = getNumber.getclicks();
//FRAME AND LAYOUT
JFrame window = new JFrame();
window.getContentPane().setBackground(Color.darkGray);
window.getContentPane().setLayout(new BorderLayout(20,10));
window.setTitle("Test Frame 1");
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(true);
// Top JPanel
JPanel northpanel = new JPanel();
LayoutManager northlayout = new FlowLayout();
northpanel.setLayout(northlayout);
// Top JPanel content
JLabel nlabel1 = new JLabel("Hello North");
nlabel1.setPreferredSize(new Dimension(100,20));
northpanel.add(nlabel1);
JPanel westpanel = new JPanel();
LayoutManager westlayout = new BoxLayout(westpanel, BoxLayout.Y_AXIS);
westpanel.setLayout(westlayout);
JLabel wlabel1 = new JLabel("Hello West");
wlabel1.setPreferredSize(new Dimension(100,20));
westpanel.add(wlabel1);
JPanel eastpanel = new JPanel();
LayoutManager eastlayout = new BoxLayout(eastpanel, BoxLayout.Y_AXIS);
eastpanel.setLayout(eastlayout);
JLabel elabel1 = new JLabel ("Hello East");
elabel1.setPreferredSize(new Dimension(100,20));
eastpanel.add(elabel1);
JButton southbutton = new JButton("start");
southbutton.setPreferredSize(new Dimension(400,50));
southbutton.addActionListener(new Action());
JPanel centralpanel = new JPanel();
JLabel clabel1 = new JLabel("Clicks: " + x);
centralpanel.add(clabel1);
window.add(centralpanel, BorderLayout.CENTER);
window.add(southbutton, BorderLayout.SOUTH);
window.add(eastpanel, BorderLayout.EAST);
window.add(westpanel, BorderLayout.WEST);
window.add(northpanel, BorderLayout.NORTH);
window.pack();
window.setVisible(true);
}
public static void main(String[] args) {
Test_1 window_start = new Test_1();
}
static class Action implements ActionListener{
#Override
public void actionPerformed (ActionEvent e){
clicks Numbers = new clicks();
Numbers.setclicks();
int test = Numbers.getclicks();
System.out.println("Button works, Number of clicks: "+test);
Test_1 updateData = new Test_1();
}
}
}
I know that the ActionListener creates a new instance of my JFrame, however that was the closest I ever came to "updating the JFrame" before I turned the code into Spaghetti. I assume that the way I build my code is the cause of my problem but creating the Frame and its content it different classes didn't work at all.
So my questions are:
Is there something really obvious I missing? Would it be possible to make this run the way I want to without completely changing it?
Is there a more efficient way to create a GUI? I get the feeling that the way I made this is total garbage.
I read other questions that dealt with similar problems but maybe it's because I am still pretty bad at Java but I couldn't really tell if they were related to my problem. Also I really want to understand this, so copying someone elses code wouldn't help at all.
Any help or comments are appreciated.
btw, the class click is something I just put there as a placeholder.

Alrighty I managed to get it to work. It's probably against the Etiquette to answer to his own question but I thought it might be useful for some beginners(like me yesterday). So here is my new code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test_1 extends JFrame {
public static class clicks{
static int clicks = 0;
public int getclicks(){
return clicks;
}
public void setclicks(){
clicks = clicks+1;
}
}
clicks getNumber = new clicks();
int x = getNumber.getclicks();
JPanel northpanel, westpanel, eastpanel, southpanel, centralpanel;
static JLabel nlabel1, nlabel2, nlabel3, nlabel4, nlabel5;
static JLabel wlabel1, wlabel2, wlabel3, wlabel4, wlabel5;
static JLabel elabel1, elabel2, elabel3, elabel4, elabel5;
static JLabel clabel1;
JButton southbutton;
String TextnL, TextwL, TexteL;
public Test_1(){
setBackground(Color.darkGray);
setLayout(new BorderLayout(20,10));
setTitle("Test Frame 1");
setSize(300,200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(true);
setLocationRelativeTo(null);
setVisible(true);
nlabel1 = new JLabel("North_1");
nlabel2 = new JLabel("North_2");
nlabel3 = new JLabel("North_3");
nlabel4 = new JLabel("North_4");
nlabel5 = new JLabel("North_5");
wlabel1 = new JLabel("West_1 ");
wlabel2 = new JLabel("West_2 ");
wlabel3 = new JLabel("West_3 ");
wlabel4 = new JLabel("West_4 ");
wlabel5 = new JLabel("West_5 ");
elabel1 = new JLabel("East_1");
elabel2 = new JLabel("East_2");
elabel3 = new JLabel("East_3");
elabel4 = new JLabel("East_4");
elabel5 = new JLabel("East_5");
clabel1 = new JLabel("START");
southbutton = new JButton("Process");
southbutton.addActionListener(new Action());
northpanel = new JPanel();
northpanel.add(nlabel1);
northpanel.add(nlabel2);
northpanel.add(nlabel3);
northpanel.add(nlabel4);
northpanel.add(nlabel5);
add(northpanel, BorderLayout.NORTH);
westpanel = new JPanel();
LayoutManager wBox = new BoxLayout(westpanel, BoxLayout.Y_AXIS);
westpanel.setLayout(wBox);
westpanel.add(wlabel1);
westpanel.add(wlabel2);
westpanel.add(wlabel3);
westpanel.add(wlabel4);
westpanel.add(wlabel5);
add(westpanel, BorderLayout.WEST);
eastpanel = new JPanel();
LayoutManager eBox = new BoxLayout(eastpanel, BoxLayout.Y_AXIS);
eastpanel.setLayout(eBox);
eastpanel.add(elabel1);
eastpanel.add(elabel2);
eastpanel.add(elabel3);
eastpanel.add(elabel4);
eastpanel.add(elabel5);
add(eastpanel, BorderLayout.EAST);
centralpanel = new JPanel();
centralpanel.add(clabel1);
add(centralpanel, BorderLayout.CENTER);
add(southbutton, BorderLayout.SOUTH);
}
public static void main(String[] args) {
Test_1 window_start = new Test_1();
}
static class Action implements ActionListener{
#Override
public void actionPerformed (ActionEvent e){
clicks Numbers = new clicks();
Numbers.setclicks();
int test = Numbers.getclicks();
clabel1.setText("clicks: "+test);
}
}
}
And again, any comments/suggestions are welcome.

JAVA - Can't add Text Field and Button to container

I'm trying to do a little program that use some buttons and text field.
I was able to create window with JPanel but don't have idea how to add button and text field
The code I'm using is:
public UI() {
sprites = new HashMap();
// spriteCache = stage.getSpriteCache();
JFrame okno = new JFrame ("VoLTE Script");
setBounds(0,0,SZEROKOSC,WYSOKOSC);
JPanel panel = (JPanel)okno.getContentPane();
panel.setLayout (null);
panel.add(this);
okno.setBounds(0,0,800,600);
okno.setVisible(true);
JTextField pole = new JTextField(10);
JButton przycisk = new JButton("teasda");
przycisk.setPreferredSize(new Dimension(300, 350));
przycisk.setLayout(new BorderLayout());
panel.add(przycisk);
przycisk.setVisible(true);
pole.setBounds (300,300,200,200);
pole.setLayout(null);
pole.setVisible(true);
panel.add(pole);
okno.addWindowListener(new WindowAdapter(){
public void windowClosing (WindowEvent e){
System.exit(0);
}
});
okno.setResizable(false);
createBufferStrategy(2);
strategia=getBufferStrategy();
requestFocus();
// addKeyListener(this);
// addMouseListener(this);
}

You need to use the layout properly, when using border layout you need to tell it which border to use (, BorderLayout.NORTH or something), check out the tutorials at oracles page.
P.S. Think of how your naming your fields etc. Naming something "przycisk" just gives me a reason not to read the code further.

Thank You for help and sorry for Polish names(fixed already).
I was able to add Text Area with scroll.
Looks like problem was in panel.add(this); putted before button and text field.
From my understanding if panel.add(this) is set before panel.add(pole); then panel.add(this) is set in front and pole is added but not seen.
Below my actual working code:
...
public UI() {
sprites = new HashMap();
// spriteCache = stage.getSpriteCache();
JFrame okno = new JFrame ("VoLTE Script");
setBounds(0,0,WIDTH,HEIGHT);
JPanel panel = (JPanel)okno.getContentPane();
panel.setLayout (null);
okno.setBounds(0,0,800,600);
okno.setVisible(true);
JTextArea pole = new JTextArea();
pole.setLayout(null);
pole.setLineWrap(true);
//pole.setBackground(Color.BLACK);
pole.setEditable(false);
JScrollPane scroll = new JScrollPane(pole);
scroll.setBounds(25,250,500,300);
scroll.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
panel.add(scroll);
panel.add(this);
okno.addWindowListener(new WindowAdapter(){
public void windowClosing (WindowEvent e){
System.exit(0);
}
});
okno.setResizable(false);
createBufferStrategy(2);
strategia=getBufferStrategy();
requestFocus();
// addKeyListener(this);
addMouseListener(this);
}
...

This code is from this site: Example of Java GUI
//Imports are listed in full to show what's being used
//could just import javax.swing.* and java.awt.* etc..
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JComboBox;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JList;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class GuiApp1 {
//Note: Typically the main method will be in a
//separate class. As this is a simple one class
//example it's all in the one class.
public static void main(String[] args) {
new GuiApp1();
}
public GuiApp1()
{
JFrame guiFrame = new JFrame();
//make sure the program exits when the frame closes
guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
guiFrame.setTitle("Example GUI");
guiFrame.setSize(300,250);
//This will center the JFrame in the middle of the screen
guiFrame.setLocationRelativeTo(null);
//Options for the JComboBox
String[] fruitOptions = {"Apple", "Apricot", "Banana"
,"Cherry", "Date", "Kiwi", "Orange", "Pear", "Strawberry"};
//Options for the JList
String[] vegOptions = {"Asparagus", "Beans", "Broccoli", "Cabbage"
, "Carrot", "Celery", "Cucumber", "Leek", "Mushroom"
, "Pepper", "Radish", "Shallot", "Spinach", "Swede"
, "Turnip"};
//The first JPanel contains a JLabel and JCombobox
final JPanel comboPanel = new JPanel();
JLabel comboLbl = new JLabel("Fruits:");
JComboBox fruits = new JComboBox(fruitOptions);
comboPanel.add(comboLbl);
comboPanel.add(fruits);
//Create the second JPanel. Add a JLabel and JList and
//make use the JPanel is not visible.
final JPanel listPanel = new JPanel();
listPanel.setVisible(false);
JLabel listLbl = new JLabel("Vegetables:");
JList vegs = new JList(vegOptions);
vegs.setLayoutOrientation(JList.HORIZONTAL_WRAP);
listPanel.add(listLbl);
listPanel.add(vegs);
JButton vegFruitBut = new JButton( "Fruit or Veg");
//The ActionListener class is used to handle the
//event that happens when the user clicks the button.
//As there is not a lot that needs to happen we can
//define an anonymous inner class to make the code simpler.
vegFruitBut.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent event)
{
//When the fruit of veg button is pressed
//the setVisible value of the listPanel and
//comboPanel is switched from true to
//value or vice versa.
listPanel.setVisible(!listPanel.isVisible());
comboPanel.setVisible(!comboPanel.isVisible());
}
});
//The JFrame uses the BorderLayout layout manager.
//Put the two JPanels and JButton in different areas.
guiFrame.add(comboPanel, BorderLayout.NORTH);
guiFrame.add(listPanel, BorderLayout.CENTER);
guiFrame.add(vegFruitBut,BorderLayout.SOUTH);
//make sure the JFrame is visible
guiFrame.setVisible(true);
}
}
For the future i will recommend you to use the extends JFrame so you can only write a gui like this without initialize a JFrame:
public class CalculatorGUI extends JFrame {
public CalculatorGUI() {
setTitle("Calculator");
setBounds(300, 300, 220, 200);
}}
I suggest you check out a couple of tutorials about how to create a Java Gui or sth.

JPanels not added to JTabbedPane

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.