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Update JLabel text

I'm working on a simple GUI. On Button press i want to increase/decrease a variable and update the corresponding JLabel.
class JFrameSetUp
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JFrameSetUp extends JFrame implements ActionListener {
private int RecHeight = 0;
private int RecWidth = 0;
//Here Buttons
JButton HeightIncrease = new JButton("+");
JButton HeightDecrease = new JButton("-");
JLabel height = new JLabel(Integer.toString(RecHeight));
JLabel width = new JLabel(Integer.toString(RecWidth));
GridLayout gridLayout = new GridLayout(2, 4);
public JFrameSetUp(){
}
public void addComponentsToPane(final Container pane){
//Create GridPanel and set Layout
JPanel grid = new JPanel();
grid.setLayout(gridLayout);
//Create buttondrawPanel and set Layout
JPanel buttondraw = new JPanel();
buttondraw.setLayout(new GridLayout(2, 0));
//Adding Components to GridPanel
//Adding Layouts to pane
pane.add(grid, BorderLayout.NORTH);
pane.add(new JSeparator(), BorderLayout.CENTER);
pane.add(buttondraw, BorderLayout.SOUTH);
}
#Override
public void actionPerformed(ActionEvent e) {
//Setting up ActionListener to Buttons
if (e.getSource() == this.HeightDecrease) {
RecHeight -= 1;
height.setText(Integer.toString(RecHeight));
} else if (e.getSource() == this.HeightIncrease) {
RecHeight += 1;
height.setText(Integer.toString(RecHeight));
}
}
}
Class with MainMethod
import javax.swing.JFrame;
public class Program {
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
//Create and set up the window.
JFrameSetUp frame = new JFrameSetUp();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
frame.addComponentsToPane(frame.getContentPane());
//Display the window.
frame.pack();
frame.setVisible(true);
}
}
I'm aware, that's kind a newbish question. I think I'm wrong with my Code Structure. Any help is appreciated.
Thanks in advance.

You never register any ActionListeners to the buttons...
HeightIncrease.addActionListener(this);
HeightDecrease.addActionListener(this);
You also never add the buttons to the GUI
buttondraw.add(HeightIncrease);
buttondraw.add(HeightDecrease);
You also never add the labels to the GUI either...
grid.add(height);
grid.add(width);
I reworked the code, because your example was messing with my mind, hope you don't mind...
It's conceptually the same idea, just done slightly more efficently
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private int recHeight = 0;
private int recWidth = 0;
//Here Buttons
JButton heightIncrease = new JButton("+");
JButton heightDecrease = new JButton("-");
JLabel height = new JLabel(Integer.toString(recHeight));
JLabel width = new JLabel(Integer.toString(recWidth));
GridLayout gridLayout = new GridLayout(2, 4);
public TestPane() {
setLayout(new BorderLayout());
//Create GridPanel and set Layout
JPanel grid = new JPanel();
grid.setLayout(gridLayout);
grid.add(height);
grid.add(width);
//Create buttondrawPanel and set Layout
JPanel buttondraw = new JPanel();
buttondraw.setLayout(new GridLayout(2, 0));
heightIncrease.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
recHeight += 1;
height.setText(Integer.toString(recHeight));
}
});
heightDecrease.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
recHeight -= 1;
height.setText(Integer.toString(recHeight));
}
});
buttondraw.add(heightIncrease);
buttondraw.add(heightDecrease);
//Adding Components to GridPanel
//Adding Layouts to pane
add(grid, BorderLayout.NORTH);
add(new JSeparator(), BorderLayout.CENTER);
add(buttondraw, BorderLayout.SOUTH);
}
}
}
I would encourage you to spend some time having a look at How to Use Buttons, Check Boxes, and Radio Buttons and How to Write an Action Listeners for more details

After changing the value call
frame.repaint();

Good to see you learning Java! A few things I should point out.
Firstly, your variable names are good, but they don't follow the Java naming convention. Even though it seems small, it's just good practice to follow.
Of course, your actual problem; the action listener you've implemented is on the JFrame. (See how you extend JFrame and implement ActionListener?) This ActionListener should be on the button. You'll can do this a few ways.
Method 1: By adding it inline with your code
JButton heightButton = new JButton("Increase Height");
heightButton.addActionListener(new ActionListener(){
#Override
public void run(){
//run method here
}
});
Method 2: Create a class which implements ActionListener
class ButtonListener implements ActionListener{
#Override
public void run(){
//actionListener code here
}
}
And then instantiate an object of this type and add it directly to your code.
ActionListner buttonListener = new ButtonListener(); //or ButtonListener buttonListener = new ButtonListener();
JButton heightButton = new JButton("Increase Height");
heightButton.addActionListener(buttonListener);
Of course, as in MadProgrammers answer, don't forget to add the labels and such to your JFrame or JPanel. Good luck learning Java!

I bet that your program just shows nothing, isn't it? That's because in addComponentsToPane method, you didn't add any component but empty JPanels. After the comment //Adding Components to GridPanel, you should:
buttondraw.add(HeightIncrease);
buttondraw.add(HeightDecrease);
grid.add(height);
grid.add(width);
Then, to listen to button event, you should also add :
HeightIncrease.addActionListener(this);
HeightDecrease.addActionListener(this);
"this" is because your frame JFrameSetUp implements ActionListener, so when either bootton is clicked the method actionPerformed is invoked.
As JLabel.setText method will repaint itself and consequently its component hierarchi is repainted as well, you haven't to do anything othr.

Java: Why validate don't work

I want to change the panel dynamically and as this answer show, they recommend to use the cardLayout. But I want to change the whole UI(no old button left) and cardLayout seems not so convenient. So I have the following code:
JFrame frame = new JFrame ("Key test");
MyDrawPanel1 dp1 = new MyDrawPanel1(frame);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible (true);
JPanel p = new JPanel ();
p.setLayout(new BorderLayout());
p.add(dp1,BorderLayout.CENTER);
frame.getContentPane().add(p);
frame.pack();
frame.setVisible (true);
And in the MyDrawPanel1 there is a button to change panel:
public MyDrawPanel1(final JFrame frame) {
clickButton.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
frame.getContentPane().removeAll();
//frame.validate();
frame.getContentPane().add(new MyDrawPanel2());
((JPanel)frame.getContentPane()).revalidate();
}
});
this.add(clickButton);
}
Edit:some more codes in MyDrawPanel1.
JButton clickButton = new JButton("click");
Image image = new ImageIcon("D:/0.jpg").getImage();
public void paintComponent (Graphics g) {
super.paintComponent(g);
g.drawImage(image, 3, 40, null);
}
public Dimension getPreferredSize() {
if (image != null) {
return new Dimension(image.getWidth(null), image.getHeight(null));
}
return super.getPreferredSize(); // default
}
But the first panel doesn't disappear and I have to minimize it to refresh it so I can see the second panel. My question is the why validate don't work and if there is any other alternatives. Thanks.
Edit:here are the pictures I snipped about the panel.(first panel):
(after clicked):
Edit:
The madProgrammer and Adarsh Singhal provide two ways to solve the problem. The first is the second the panel don't call the super.paintComponent(), so add it then it works fine (as this answer say, it is the eraser so the first panel was gone). The second is calling the frame.repaint(), but I don't understand why?

We've to use repaint() to tell the components to repaint themselves. Visualize it as your case. While revalidate is used to update the layouts. So, whenever you add/remove components dynamically, you need to call both of them.The following written code displays a JFrame set to CardLayout to draw Red dp1(JPanel) completely on JFrame. On dp1, there is a Jbutton. If you click that button, dp1 will be removed & dp2(JPanel) will be drawn. dp2 is Green to distinguish changes. It seems you've forgotten repaint().
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MyFrame extends JFrame{
JButton button;
private static MyFrame frame;
public MyFrame(){
this.setSize(400, 400);
this.setLayout(new CardLayout());
this.setLocationRelativeTo(null);
JPanel dp1 = new JPanel();
dp1.setBackground(Color.RED);
add(dp1);
button = new JButton("Click me to remove dp1 & draw dp2");
dp1.add (button);
JPanel dp2 = new JPanel ();
dp2.setBackground(Color.GREEN);
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent arg0) {
frame.getContentPane().remove(dp1);
frame.add(dp2);
frame.revalidate();
frame.repaint();
}});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible (true);
}
public static void main(String[] args) {
frame = new MyFrame();
}
}

How would I use a button in Java to open Jframe over existing Jframe

I have 2 frames, the first frame has the nothing more and a button, which leads to another frame which will have all the components, like tabs which have more components.
The code I am using is:
button_1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e) {
JFrame Frame_2 = new JFrame();
Frame_1.setVisible(false);
Frame_2.setVisible(true);
}
});
this is creating a new separate frame , but i want to create new JFrame over existing JFrame
update
#VinceEmigh +1
Thanks for the detail custom solution. It shows that someone is really willing to help, I am a self learner , started just 3 months ago so your code is bit difficult to understand, but the idea of using cardlayout did the work and i came up with a solution.
JFrame guiFrame = new JFrame();
CardLayout cards;
JPanel cardPane;
JButton B_1 = new JButton("Next Card");
B_1.setActionCommand("Next Card");
B_1.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent event)
{
cards.next(cardPane);
}
});
cards = new CardLayout();
cardPane = new JPanel();
cardPane.setLayout(cards);
cards.show(cardPane, "Main");
JPanel Card_1 = new JPanel();
JLabel background_1 = new JLabel(new ImageIcon("C:\\Users\\ME\\Desktop\\Back1.jpg"));
Card_1.add(background_1);
Card_1.add(B_1);
JPanel Card_2 = new JPanel();
JLabel background_2 = new JLabel(new ImageIcon("C:\\Users\\ME\\Desktop\\Back2.jpg"));
Card_2.add(background_2);
cardPane.add(Card_1, "Main");
cardPane.add(Card_2, "Sub");

You shouldnt use 2 frames. You should use 1 frame, then switch between panels in the frame using CardLayout. Unless you're referring to nesting a frame within a frame, creating 2 different frames for 1 applicarion is typically bad practice, and should be avoided if possible.
Set your frames layout to CardLayout, add 2 panels to your frame. One panel contains the button, the other has the components.
When your button event triggers throuhh an actionlistener, switch out the panels using the cardlayout you put for the frames layout.
import java.awt.CardLayout;
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 App extends JFrame {
private CardLayout cl = new CardLayout();
private JPanel firstPanel = new FirstPanel();
private JPanel secondPanel = new SecondPanel();
public App() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(500, 500);
setLayout(cl);
add(firstPanel, "first");
add(secondPanel, "second");
setLocationRelativeTo(null);
setVisible(true);
}
public void switchPanel(String name) {
cl.show(getContentPane(), name);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
App app = new App();
}
});
}
class FirstPanel extends JPanel implements ActionListener {
private JButton button = new JButton("Button");
public FirstPanel() {
button.addActionListener(this);
add(button);
}
public void actionPerformed(ActionEvent e) {
if(e.getSource() == button) {
switchPanel("second");
}
}
}
class SecondPanel extends JPanel { }
}

Set JTextFields and JButtons position in CardLayout

This is a java template i found about Card Layout
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Main {
private static final String CARD_JBUTTON = "Card JButton";
private static final String CARD_JTEXTFIELD = "Card JTextField";
private static final String CARD_JRADIOBUTTON = "Card JRadioButton";
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Card Layout Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
// This JPanel is the base for CardLayout for other JPanels.
final JPanel contentPane = new JPanel();
contentPane.setLayout(new CardLayout(200, 200));
/* Here we be making objects of the Window Series classes
* so that, each one of them can be added to the JPanel
* having CardLayout.
*/
Window1 win1 = new Window1();
contentPane.add(win1, CARD_JBUTTON);
Window2 win2 = new Window2();
contentPane.add(win2, CARD_JTEXTFIELD);
Window3 win3 = new Window3();
contentPane.add(win3, CARD_JRADIOBUTTON);
/* We need two JButtons to go to the next Card
* or come back to the previous Card, as and when
* desired by the User.
*/
JPanel buttonPanel = new JPanel();
final JButton previousButton = new JButton("PREVIOUS");
previousButton.setBackground(Color.BLACK);
previousButton.setForeground(Color.WHITE);
final JButton nextButton = new JButton("NEXT");
nextButton.setBackground(Color.RED);
nextButton.setForeground(Color.WHITE);
buttonPanel.add(previousButton);
buttonPanel.add(nextButton);
/* Adding the ActionListeners to the JButton,
* so that the user can see the next Card or
* come back to the previous Card, as desired.
*/
previousButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.previous(contentPane);
}
});
nextButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.next(contentPane);
}
});
// Adding the contentPane (JPanel) and buttonPanel to JFrame.
frame.add(contentPane, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
And this is my Window1.java
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
class Window1 extends JPanel
{
/*
* Here this is our first Card of CardLayout, which will
* be added to the contentPane object of JPanel, which
* has the LayoutManager set to CardLayout.
* This card consists of Two JButtons.
*/
private ActionListener action;
public Window1()
{
init();
}
private void init()
{
final JButton clickButton = new JButton("Click ME");
final JButton dontClickButton = new JButton("DON\'T CLICK ME");
final JTextField title = new JTextField(12);
action = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
if (ae.getSource() == clickButton)
{
String myString = title.getText();
System.out.println(myString);
}
else if (ae.getSource() == dontClickButton)
{
JOptionPane.showMessageDialog(null, "I told you not to click me!"
, "Wrong Button", JOptionPane.PLAIN_MESSAGE);
}
}
};
clickButton.addActionListener(action);
dontClickButton.addActionListener(action);
add(clickButton);
add(dontClickButton);
add(title);
}
}
Now my problem is that how do i set the position of the textfields and buttons in Window1?
With this code they are set in the center of the view aligned horizontally.
I tried to use title.setLocation(5,5); but it's not working. Any suggestions?

Now my problem is that how do i set the position of the textfields and buttons in Window1?
Rows like Jlabel - JTextField then new row ,and in the end of the page the button
The thing is you're not using any layout managers. The default layout manager for JPanel is FlowLayout, which will do exactly what you're experiencing (horizontal layout of the components).
Getting vertical alignment could be achieved by using different layout managers. You could use a GridBagLayout for all the component, or a GridLayout, or you could nest JPanel with different layout managers. The possibilities are endless. It just comes down to the exact look you want.
See Laying out Components Within a Container to learn how to use different layout managers. I'll give you an example, but don't let it stop you from looking at the tutorials. You need to learn them.
Also besides just positioning of the components layout managers use dynamic sizing either by respecting the preferred of components are not respecting them. You can see a picture in this answer of some of the layout managers that do and don't respect preferred sizes.
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class LayoutManagers extends JPanel{
public LayoutManagers() {
JLabel label = new JLabel("Text Field");
JTextField textField = new JTextField(20);
JRadioButton rb1 = new JRadioButton("Radio 1");
JRadioButton rb2 = new JRadioButton("Radio 2");
JButton button = new JButton("Button");
JPanel panel1 = new JPanel();
panel1.add(label);
panel1.add(textField);
JPanel panel2 = new JPanel();
panel2.add(rb1);
panel2.add(rb2);
JPanel panel3 = new JPanel(new FlowLayout(FlowLayout.TRAILING));
panel3.add(button);
JPanel panel4 = new JPanel(new GridLayout(3, 1));
panel4.add(panel1);
panel4.add(panel2);
panel4.add(panel3);
setLayout(new GridBagLayout());
add(panel4);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run() {
JFrame frame = new JFrame();
frame.add(new LayoutManagers());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
});
}
}

How can I replace one of two JPanels with another JPanel in Java?

I designed an interface for the welcome screen with one JFrame included two JPanels (JPanel1 on right and JPanel2 on left). The buttons on the left is to switch the Panels in JPanel1. I want to press on a button to replace JPanel1 content with another JPanel but I don`t know how. Please help.

Here is a very simple example of something that should approximate your description. On the left, we have a hug button to toggle the content of the right panel. On the right, you have a panel with a given border and a label. When you press the button, the content on the right is swapped with the other panel.
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class TestCardLayout2 {
protected void initUI() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel leftPanel = new JPanel(new BorderLayout());
JLabel label = new JLabel("Left panel");
leftPanel.add(label, BorderLayout.NORTH);
JButton button = new JButton("Toggle right panel");
leftPanel.add(button);
frame.add(leftPanel, BorderLayout.WEST);
final CardLayout cardLayout = new CardLayout();
final JPanel rightPanel = new JPanel(cardLayout);
rightPanel.setPreferredSize(new Dimension(200, 500));
JPanel rightPanel1 = new JPanel(new FlowLayout(FlowLayout.LEFT));
rightPanel1.setBorder(BorderFactory.createLineBorder(Color.RED));
JPanel rightPanel2 = new JPanel(new FlowLayout(FlowLayout.RIGHT));
rightPanel2.setBorder(BorderFactory.createLineBorder(Color.BLUE));
JLabel label1 = new JLabel("Right panel 1 with a red border");
JLabel label2 = new JLabel("Right panel 2 with a blue borer");
rightPanel1.add(label1);
rightPanel2.add(label2);
rightPanel.add(rightPanel1, "panel1");
rightPanel.add(rightPanel2, "panel2");
frame.add(rightPanel, BorderLayout.EAST);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
cardLayout.next(rightPanel);
}
});
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TestCardLayout2().initUI();
}
});
}
}

An alternative to CardLayout would be JRootPane and its JRootPane.setContentPane() method. Here's an example:
final JPanel panel1 = ...;
final JPanel panel2 = ...;
boolean showingPanel1 = true;
final JRootPane rootPane = new JRootPane();
rootPane.setContentPane(panel1);
JButton switchButton = new JButton("Switch");
switchButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (showingPanel1) {
rootPane.setContentPane(panel2);
} else {
rootPane.setContentPane(panel1);
}
showingPanel = !showingPanel;
}
});
Add the rootPane and switchButton components to your window, and then clicking switchButton will switch out the panels.
Here's a tutorial. You should mostly be concerned with JRootPane.setContentPane, the other stuff in the tutorial isn't relevant.

The best answer I found is that I will create one JFrame only and gonna make one big JPanel include two JPanels (JPanelLeft include the buttons and JPanelRight include what the button do) then I will copy the main JPanel for each JButton.
When I press on any button I will do (JFrame.getContentPane.removeAll) to remove the old JPanel then (JFrame.getContentPane.Add(NewJPanel).
This works for me and keep my design as I Want. Thanks for every body.