I am newbie to Java. My following code give me a blank window.
Anyone can help me with what is going on ?
I am thinking that the error is at the ActionListeners.
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("Listeners");
frame.setSize(400, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setLayout(new BorderLayout());
JTextArea txtArea = new JTextArea();
HelloActionListener hlisten = new HelloActionListener(txtArea);
JButton bl = new JButton("TOP");
bl.addActionListener((ActionListener) hlisten);
JButton b2 = new JButton("LEFT");
ActionListener rightListener = (ActionEvent e) -> {
txtArea.setText("Yes,let's go Left");
};
b2.addActionListener(rightListener);
JButton b3 = new JButton("RIGHT");
b3.addActionListener((ActionEvent e) -> {
txtArea.setText("Sorry, we cant go Right");
});
JButton b4 = new JButton("Bottom");
b4.addActionListener((ActionListener) hlisten);
frame.add(bl, BorderLayout.PAGE_START);
frame.add(b2, BorderLayout.LINE_START);
frame.add(b3, BorderLayout.LINE_END);
frame.add(b4, BorderLayout.PAGE_END);
frame.add(txtArea, BorderLayout.CENTER);
frame.setVisible(true);
}
Say you want to put "Hello" in your text area when the top button is pressed. Then you need to define your HelloActionListener as below:
private static class HelloActionListener implements ActionListener {
private JTextArea textArea;
public HelloActionListener(JTextArea textArea) {
this.textArea = textArea;
}
#Override
public void actionPerformed(ActionEvent e) {
textArea.setText("Hello");
}
}
The rest of your code is kind of messy but should work, however, you don't need to make the frame to be visible twice.
UPDATE
But I do think your code should be something like this:
public class MyApplication extends JFrame {
public MyApplication() {
setTitle("Listeners");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
JTextArea txtArea = new JTextArea();
HelloActionListener hlisten = new HelloActionListener(txtArea);
JButton bl = new JButton("TOP");
bl.addActionListener(hlisten);
JButton b2 = new JButton("LEFT");
ActionListener rightListener = e -> {
txtArea.setText("Yes,let's go Left");
};
b2.addActionListener(rightListener);
JButton b3 = new JButton("RIGHT");
b3.addActionListener(e -> {
txtArea.setText("Sorry, we cant go Right");
});
JButton b4 = new JButton("Bottom");
b4.addActionListener(hlisten);
add(bl, BorderLayout.PAGE_START);
add(b2, BorderLayout.LINE_START);
add(b3, BorderLayout.LINE_END);
add(b4, BorderLayout.PAGE_END);
add(txtArea, BorderLayout.CENTER);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new MyApplication();
frame.pack();
frame.setVisible(true);
});
}
private class HelloActionListener implements ActionListener {
private JTextArea textArea;
public HelloActionListener(JTextArea textArea) {
this.textArea = textArea;
}
#Override
public void actionPerformed(ActionEvent e) {
JButton button = (JButton) e.getSource();
textArea.setText("Hello from " + button.getText());
}
}
}
There is no need for the first frame.setVisible(true); in your code - you are calling that again right at the end. But your panels are all zero size. You need to call frame.pack(); before you set it visible. Note also that all of that (the GUI stuff) should be done from the Event Dispatch Thread, not from your main thread.
Related
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.
For some reason I can't get the BorderLayout to set the way it's supposed to. Just would like to know where I'm going wrong.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ColorFactory extends JFrame
{
final int width = 500;
final int height = 300;
private JPanel buttonPanel;
private JPanel radioButtonPanel;
private JLabel msgChangeColor;
public ColorFactory()
{
setTitle("Color Factory");
setSize(width, height);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
createTopPanel();
add(buttonPanel, BorderLayout.NORTH);
createBottomPanel();
add(radioButtonPanel, BorderLayout.SOUTH);
msgChangeColor = new JLabel("Top buttons change the panel color and bottom radio buttons change the text color.");
add(msgChangeColor, BorderLayout.CENTER);
pack();
}
private void createTopPanel()
{
buttonPanel = new JPanel();
setLayout(new FlowLayout());
JButton redButton = new JButton("Red");
redButton.setBackground(Color.RED);
redButton.addActionListener(new ButtonListener());
redButton.setActionCommand("R");
JButton orangeButton = new JButton("Orange");
orangeButton.setBackground(Color.ORANGE);
orangeButton.addActionListener(new ButtonListener());
orangeButton.setActionCommand("O");
JButton yellowButton = new JButton("Yellow");
yellowButton.setBackground(Color.YELLOW);
yellowButton.addActionListener(new ButtonListener());
yellowButton.setActionCommand("Y");
buttonPanel.add(redButton);
buttonPanel.add(orangeButton);
buttonPanel.add(yellowButton);
}
private void createBottomPanel()
{
radioButtonPanel = new JPanel();
setLayout(new FlowLayout());
JRadioButton greenRadioButton = new JRadioButton("Green");
greenRadioButton.setBackground(Color.GREEN);
greenRadioButton.addActionListener(new RadioButtonListener());
greenRadioButton.setActionCommand("G");
JButton blueRadioButton = new JButton("Blue");
blueRadioButton.setBackground(Color.BLUE);
blueRadioButton.addActionListener(new RadioButtonListener());
blueRadioButton.setActionCommand("B");
JButton cyanRadioButton = new JButton("Cyan");
cyanRadioButton.setBackground(Color.CYAN);
cyanRadioButton.addActionListener(new RadioButtonListener());
cyanRadioButton.setActionCommand("C");
radioButtonPanel.add(greenRadioButton);
radioButtonPanel.add(blueRadioButton);
radioButtonPanel.add(cyanRadioButton);
}
private class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String actionColor = e.getActionCommand();
if(actionColor.equals("R"))
{
buttonPanel.setBackground(Color.RED);
radioButtonPanel.setBackground(Color.RED);
}
if(actionColor.equals("O"))
{
buttonPanel.setBackground(Color.ORANGE);
radioButtonPanel.setBackground(Color.ORANGE);
}
if(actionColor.equals("Y"))
{
buttonPanel.setBackground(Color.YELLOW);
radioButtonPanel.setBackground(Color.YELLOW);
}
}
}
private class RadioButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String actionTextColor = e.getActionCommand();
if(actionTextColor.equals("G"))
{
msgChangeColor.setForeground(Color.GREEN);
}
if(actionTextColor.equals("B"))
{
msgChangeColor.setForeground(Color.BLUE);
}
if(actionTextColor.equals("C"))
{
msgChangeColor.setForeground(Color.CYAN);
}
}
}
public static void main(String[] args)
{
ColorFactory run = new ColorFactory();
run.setVisible(true);
}
}
The problem is you are changing the layout manager for the frame when you create your top and bottom panels...
private void createTopPanel() {
buttonPanel = new JPanel();
setLayout(new FlowLayout()); // <--- This is call setLayout on the frame
This is why it's dangerous to...
Extend from something like JFrame directly...
Dynamically build components
It's all to easy to lose context and start effecting components you didn't actually want to...
Another problem (besides the one posted by MadProgrammer) is that you add your components to the JFrame itself.
You should add content to the content pane of the frame which you can get by calling JFrame.getContentPane().
Example:
JFrame f = new JFrame("Test");
Container c = f.getContentPane();
c.add(new JButton("In Center"), BorderLayout.CENTER);
c.add(new JButton("At the Bottom"), BorderLayout.SOUTH);
c.add(new JButton("At the Top"), BorderLayout.NORTH);
c.add(new JButton("On the Left"), BorderLayout.WEST);
c.add(new JButton("On the Right"), BorderLayout.EAST);
You can set/change the content panel by calling JFrame.setContentPane(). The default content panel already has BorderLayout so you don't even need to change it nor to set a new panel.
This is the JPanel
public class DisplayBoard {
public static void main (String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//The main panel
JPanel main = new JPanel();
main.setPreferredSize(new Dimension(600,800) );
main.setLayout(new BorderLayout());
//The title panel
JPanel title = new JPanel();
title.setPreferredSize(new Dimension(400, 120));
title.setBackground(Color.YELLOW);
JLabel test1 = new JLabel("Title goes here");
title.add(test1);
//The side bar panel
JPanel sidebar = new JPanel();
sidebar.setPreferredSize(new Dimension(200, 800));
sidebar.add(AddSubtract);
sidebar.setBackground(Color.GREEN);
JLabel test2 = new JLabel("Sidebar goes here");
sidebar.add(test2);
//The panel that displays all the cards
JPanel cardBoard = new JPanel();
cardBoard.setPreferredSize(new Dimension(400,640) );
//adding panels to the main panel
main.add(cardBoard, BorderLayout.CENTER);
main.add(title, BorderLayout.NORTH);
main.add(sidebar, BorderLayout.WEST);
frame.setContentPane(main);
frame.pack();
frame.setVisible(true);
}
}
and I want to add this class into the sidebar panel
public class AddSubtract {
int Number = 0;
private JFrame Frame = new JFrame("Math");
private JPanel ContentPane = new JPanel();
private JButton Button1 = new JButton("Add");
private JButton Button2 = new JButton("Subtract");
private JLabel Num = new JLabel ("Number: " + Integer.toString (Number));
public AddSubtract() {
Frame.setContentPane(ContentPane);
ContentPane.add(Button1);
ContentPane.add(Button2);
ContentPane.add(Num);
Button1.addActionListener(new Adding());
Button2.addActionListener(new Subtracting());
}
public class Adding implements ActionListener {
public void actionPerformed(ActionEvent e) {
Number++;
Num.setText ("Number: " + Integer.toString (Number));
}
}
public class Subtracting implements ActionListener {
public void actionPerformed(ActionEvent e) {
Number--;
Num.setText ("Number: " + Integer.toString (Number));
}
}
public void launchFrame(){
Frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Frame.pack();
Frame.setVisible(true);
}
public static void main(String args[]){
AddSubtract Test = new AddSubtract();
Test.launchFrame();
}
}
Can someone explain to me how I can do this ?
I have a feeling that this is not going to work, but I really want to learn the way to do it.
This definately is not going to work. For starters, you have two main() methods. Second, if you want to add a class to your Frame, it should extend from JComponent. Basically, your code should look like this:
public class MainFrame extends JFrame {
public MainFrame() {
this.add(new MainPanel())
//insert all settings here.
}
}
public class MainPanel extends JPanel {
public MainPanel() {
this.add(new AddSubtract());
this.add(/*more panels*/)
}
}
public class AddSubtract extends JPanel {
public AddSubtract() {
//add buttons and stuff here
}
}
and variables do NOT start with capitals.
Edit: And when you have some JFrame, it's usually best to have a main() method with just one line:
public static void main(String[] args) {
new MainFrame();
}
just set the settings and configuration of the JFrame in the constructor.
can any one tell me how to add a panel in a jtabbedPane whenever i am clicking on a "add" button.Its like google chrome new tab.But the thing is ,the generated panel must contains some default components.Thanks in advance.
Please see the code below. It shows you how to do what you need.
public class DemoApp {
private JTabbedPane tabPane = new JTabbedPane();
public DemoApp() {
initComponents();
}
private void initComponents() {
JFrame frame = new JFrame("Test");
frame.setSize(500, 400);
frame.setLocationRelativeTo(null);
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
frame.getContentPane().add(panel);
JButton btn = new JButton("Add panel");
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int index = tabPane.getTabCount() + 1;
JPanel newPanel = new JPanel();
newPanel.setLayout(new FlowLayout());
newPanel.add(new JLabel("Panel " + index));
tabPane.addTab("Tab " + index, newPanel);
}
});
panel.add(tabPane, BorderLayout.CENTER);
panel.add(btn, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public static void main(String[] args) {
new DemoApp();
}
}
How to close current frame (Frame1) and open a new frame (Frame2) already created and pass the data to frame2 from frame1 on the clicking of button?
Use a CardLayout1. Either that or one JFrame and one or more JDialog2 instances.
How to Use CardLayout
How to Make Dialogs
The very best way to accomplish this, is very much told to you by #Andrew Thompson.
And the other way to accomplish, the motive of the question as described in the code. Here as you make object of your new JFrame, you have to pass the things you need in the other class as an argument to the other class, or you can simply pass the object(with this you be passing everything in one go to the other class)
A sample code for a bit of help :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TwoFramesExample
{
public JFrame frame;
private JPanel panel;
private JButton button;
private JTextField tfield;
private SecondFrame secondFrame;
public TwoFramesExample()
{
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
panel = new JPanel();
panel.setLayout(new BorderLayout());
tfield = new JTextField(10);
tfield.setBackground(Color.BLACK);
tfield.setForeground(Color.WHITE);
button = new JButton("NEXT");
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
// Here we are passing the contents of the JTextField to another class
// so that it can be shown on the label of the other JFrame.
secondFrame = new SecondFrame(tfield.getText());
frame.dispose();
}
});
frame.setContentPane(panel);
panel.add(tfield, BorderLayout.CENTER);
panel.add(button, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new TwoFramesExample();
}
});
}
}
class SecondFrame
{
private JFrame frame;
private JPanel panel;
private JLabel label;
private JButton button;
private TwoFramesExample firstFrame;
public SecondFrame(String text)
{
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
panel = new JPanel();
panel.setLayout(new BorderLayout());
label = new JLabel(text);
button = new JButton("BACK");
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
firstFrame = new TwoFramesExample();
frame.dispose();
}
});
frame.setContentPane(panel);
panel.add(label, BorderLayout.CENTER);
panel.add(button, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
}
Hope this be of some help.
Regards