Develop Reference

JPanel won't update

I've hit a problem in getting a JPanel to update.
My simple program uses a custom JPanel which displays a label and a textfield. A Jbutton on the main panel is used to replace the JPanel with a new JPanel. The initial panel shows up fine but when the button is pressed the panel is not updated with a new MyPanel. I can tell that a new object is being created as count is being incremented.
public class SwingTest extends JFrame{
private JPanel mp;
private JPanel vp;
private JButton button;
public static void main(String[] args) {
SwingTest st = new SwingTest();
}
public SwingTest() {
vp = new MyPanel();
mp = new JPanel(new BorderLayout());
mp.add(vp, BorderLayout.CENTER);
button = new JButton("Change");
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent ae) {
vp = new MyPanel();
vp.revalidate();
}
});
mp.add(button, BorderLayout.SOUTH);
this.add(mp);
this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setSize(250, 150);
pack();
setVisible(true);
}
}
and my custom panel....
public class MyPanel extends JPanel{
private JLabel label;
private JTextField tf;
static int count = 0;
public MyPanel(){
count++;
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
setPreferredSize(new Dimension(400, 200));
c.gridx = 0;
c.gridy = 0;
label = new JLabel(String.valueOf(count));
tf = new JTextField(10);
add(label,c);
c.gridx = 1;
add(tf, c);
}
}

You state:
A Jbutton on the main panel is used to replace the JPanel with a new JPanel.
And yet this code:
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent ae) {
vp = new MyPanel();
vp.revalidate();
}
});
and yet this code does not do this at all. All it does is change the JPanel referenced by the vp variable, but has absolutely no effect on the JPanel that is being displayed by the GUI, which suggests that you're confusing reference variable with reference or object. To change the JPanel that is displayed, you must do exactly this: add the new JPanel into the container JPanel into the BorderLayout.CENTER (default) position, then call revalidate() and repaint() on the container.
e.g.,
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
// vp = new MyPanel();
// vp.revalidate();
mp.remove(vp); // remove the original MyPanel from the GUI
vp = new MyPanel(); // create a new one
mp.add(vp, BorderLayout.CENTER); // add it to the container
// ask the container to layout and display the new component
mp.revalidate();
mp.repaint();
}
});
Or better still -- use a CardLayout to swap views.
Or better still -- simply clear the value held by the JTextField.
For more on the distinction between reference variable and object, please check out Jon Skeet's answer to this question: What is the difference between a variable, object, and reference?

JRadioButton toggle unexpectedly in CardLayout panels

So the problem is: I'm trying to make a wizard-like CardLayout. In each card panel, I put back & next JButton and 3 JRadioButton to switch between 3 pages.
Now, when I select the radio buttons the 1st time, it works normally. However, the 2nd time I select the radio button, they don't get selected as expected. For example, I want to select page 2, the card panel 2 does show up, but the radio button 2 state does not show that it's being selected, instead either radio button 1 or 3 gets selected. Button 2 only gets selected when I click it again. Same thing happens when I try to select the others.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CardLayoutWizardDemo extends JFrame{
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable() {
public void run() {
CardLayoutWizardDemo frame= new CardLayoutWizardDemo();
frame.init();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
private static final long serialVersionUID = 1L;
private JPanel cardPanel, panel1, panel2, panel3, btnPanel1, btnPanel2, btnPanel3;
private JLabel label1, label2, label3;
private JRadioButton step1, step2, step3;
private ButtonGroup bg;
private CardLayout cl = new CardLayout();
private void init(){
setTitle("CardLayoutWizardDemo");
cardPanel = new JPanel();
cardPanel.setLayout(cl);
panel1 = new JPanel(new BorderLayout());
panel2 = new JPanel(new BorderLayout());
panel3 = new JPanel(new BorderLayout());
label1 = new JLabel("label 1");
label2 = new JLabel("label 2");
label3 = new JLabel("label 3");
panel1.add(label1, BorderLayout.NORTH);
panel2.add(label2, BorderLayout.NORTH);
panel3.add(label3, BorderLayout.NORTH);
btnPanel1 = new JPanel();
btnPanel2 = new JPanel();
btnPanel3 = new JPanel();
btnPanel1.setName("panel1");
btnPanel2.setName("panel2");
btnPanel3.setName("panel3");
btnPanel1 = initTutBtn(btnPanel1);
btnPanel2 = initTutBtn(btnPanel2);
btnPanel3 = initTutBtn(btnPanel3);
panel1.add(btnPanel1, BorderLayout.SOUTH);
panel2.add(btnPanel2, BorderLayout.SOUTH);
panel3.add(btnPanel3, BorderLayout.SOUTH);
cardPanel.add(panel1, "1");
cardPanel.add(panel2,"2");
cardPanel.add(panel3,"3");
getContentPane().add(cardPanel, BorderLayout.CENTER);
setPreferredSize(new Dimension(350,500));
setMinimumSize(new Dimension(240,320));
pack();
setLocationByPlatform(true);
}
/**create new set of 3 step buttons
*/
private JPanel initTutBtn(JPanel btnPanel){
btnPanel.setLayout(new BoxLayout(btnPanel,BoxLayout.X_AXIS));
step1 = new JRadioButton();
step2 = new JRadioButton();
step3 = new JRadioButton();
step1.setActionCommand("step1");
step2.setActionCommand("step2");
step3.setActionCommand("step3");
bg = new ButtonGroup();
bg.add(step1);
bg.add(step2);
bg.add(step3);
if (btnPanel.getName().equals("panel1")){
step1.setSelected(true);
}else if (btnPanel.getName().equals("panel2")){
step2.setSelected(true);
}else if (btnPanel.getName().equals("panel3")){
step3.setSelected(true);
}
step1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
goToStep(e);
}
});
step2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
goToStep(e);
}
});
step3.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
goToStep(e);
}
});
btnPanel.add(step1);
btnPanel.add(step2);
btnPanel.add(step3);
return btnPanel;
}
private void goToStep(ActionEvent evt){
if(evt.getActionCommand().equals("step1")){
cl.show(cardPanel, "1");
}else if(evt.getActionCommand().equals("step2")){
cl.show(cardPanel, "2");
}else if(evt.getActionCommand().equals("step3")){
cl.show(cardPanel, "3");
}
}
}
I think maybe the problems lie where I create new radio buttons within initButton() and goToStep(ActionEvent evt)but I can't figure out what I did wrong

how to identify dynamically created jbutton actions

I create two jbuttons in one panel(can be Box).i create same panel dynamically several times in same frame.so if two panels created dynamically those button make with same variable name.But i want to identify buttons one by one for put actions.how to identify dynamically created buttons one by one?
button creating code
public class Jscrollpanetest extends JFrame {
JScrollPane scrollPane;
Box box;
private static int panelCount = 0;
public Jscrollpanetest() {
setPreferredSize(new Dimension(200, 400));
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
scrollPane = new JScrollPane();
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.getVerticalScrollBar().setUnitIncrement(15);
box = Box.createVerticalBox();
scrollPane.getViewport().add(box);
this.add(scrollPane);
this.pack();
this.setLocationRelativeTo(null);
this.setVisible(true);
Timer t = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent ae) {
box.add(new TestPanel(), box.size());
scrollPane.validate();
}
});
t.setRepeats(true);
t.start();
}
public class TestPanel extends JPanel {
int myId = panelCount++;
public TestPanel() {
this.setLayout(new GridBagLayout());
this.setBorder(BorderFactory.createBevelBorder(1));
JButton up = new JButton("^");
JLabel rate = new JLabel("1");
JButton down = new JButton("^");
JLabel label = new JLabel("" + myId);
label.setHorizontalAlignment(JLabel.CENTER);
label.setVerticalAlignment(JLabel.CENTER);
this.setMaximumSize(new Dimension(1000, 200));
this.setPreferredSize(new Dimension(1000, 100));
this.add(label);
this.add(up);
this.add(rate);
this.add(down);
}
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
Jscrollpanetest testScrollPane = new Jscrollpanetest();
}
});
}
}

If use and dynamic created ActionListener there will be no problem. So each button will have its own ActionListener.
If using a common ActionListener must add tags to each button as extend JButton.

Trying to use cards layout, but cant make show work

im trying to to use cards layout, and i have 2 buttons at the the top that supoose to change the card but for some reason it wont work, the next method works but the show or first\last doesnt, ofcourse i cant use next, cause i want a specific card for every button, here is my code:
cards = new CardLayout();
cardPanel = new JPanel();
cardPanel.setLayout(cards);
cards.show(cardPanel, "gapas");
JPanel firstCard = new JPanel();
firstCard.setBackground(Color.WHITE);;
JPanel secondCard = new JPanel();
secondCard.setBackground(Color.blue);
cardPanel.add(firstCard, "kalam");
cardPanel.add(secondCard, "gapan");
guiFrame.add(tabsPanel,BorderLayout.NORTH);
guiFrame.add(cardPanel,BorderLayout.CENTER);
guiFrame.setVisible(true);
}
ActionListener action = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand().matches("kalam")){
cards.show(cardPanel,"kalam");
System.out.println("kalam");
}
else{
cards.show(cardPanel, "gapas");
System.out.println("gapas");
}
}
};

I think you want something like this.
public class TestCard extends JFrame implements ActionListener {
CardLayout cards;
JPanel cardPanel, tabsPanel;
JButton b1, b2;
public TestCard() {
b1= new JButton("kalam");
b2= new JButton("gapas");
tabsPanel = new JPanel();
cards = new CardLayout();
cardPanel = new JPanel();
cardPanel.setLayout(cards);
JPanel firstCard = new JPanel();
firstCard.setBackground(Color.WHITE);
JPanel secondCard = new JPanel();
secondCard.setBackground(Color.blue);
cardPanel.add(firstCard, "kalam");
cardPanel.add(secondCard, "gapas");
tabsPanel.add(b1);
tabsPanel.add(b2);
add(tabsPanel, BorderLayout.NORTH);
add(cardPanel, BorderLayout.CENTER);
b1.addActionListener(this);
b2.addActionListener(this);
setSize(800, 600);
cards.show(cardPanel, "gapas");
setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().matches("kalam")) {
cards.show(cardPanel, "kalam");
System.out.println("kalam");
} else {
cards.show(cardPanel, "gapas");
System.out.println("gapas");
}
}
public static void main(String[] args) {
new TestCard();
}
}

Documentation states:
show (Container parent, String name) Flips to the component that was added to this layout with the specified name, using the addLayoutComponent method.
You add two items:
kalam
gapan
but you try to show: gapas.
Additionally I would add first and then try 2 show.

Adding label and text box control to GUI

I would like to know what code to insert and where to add a simple label that can just say the word "Label" and a input text box that I can enter a number.
public CalculateDimensions() {
JTabbedPane Tab = new JTabbedPane();
JPanel jplInnerPanel1 = createInnerPanel("First Tab");
Tab.addTab("One", jplInnerPanel1);
Tab.setSelectedIndex(0);
JPanel jplInnerPanel2 = createInnerPanel("Second Tab");
Tab.addTab("Two", jplInnerPanel2);
JPanel jplInnerPanel3 = createInnerPanel("Third Tab");
Tab.addTab("Three", jplInnerPanel3);
JPanel jplInnerPanel4 = createInnerPanel("Fourth Tab");
Tab.addTab("Four", jplInnerPanel4);
JPanel jplInnerPanel5 = createInnerPanel("Fifth Tab");
Tab.addTab("Five", jplInnerPanel5);
setLayout(new GridLayout(1, 1));
add(Tab);
}
protected JPanel createInnerPanel(String text) {
JPanel jplPanel = new JPanel();
JLabel jlbDisplay = new JLabel(text);
jlbDisplay.setHorizontalAlignment(JLabel.CENTER);
jplPanel.setLayout(new GridLayout(1, 1));
jplPanel.add(jlbDisplay);
return jplPanel;
}
public static void main(String[] args) {
JFrame frame = new JFrame("Calculations");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
frame.getContentPane().add(new CalculateDimensions(),
BorderLayout.CENTER);
frame.setSize(400, 400);
frame.setVisible(true);
}
}

The Swing tutorial is an excellent resource for building GUIs.
Take a look at the visual guide and click on the components you want for detailed how to guides for creating text boxes, and other items.
http://download.oracle.com/javase/tutorial/ui/features/components.html

in your public static void main() method you should not instantiate JFrame frame = new JFrame("Calculations");
This is where you are going wrong!
That line should read:
CalculateDimensions frame = new CalculateDimensions("Calculations");
You will also need to change the line says
public class CalculateDimensions {
(it's near the top) says
public class CalculateDimensions extends JFrame {
then inside the method called public class CalculateDimensions { you need to add a line after JPanel jplInnerPanel1 = createInnerPanel("First Tab"); which says
jplInnerPanel1.add(new JLabel("Label");