I'm trying to reset my JTextField in case that Space is typed. It throws me:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification
my code is:
import java.awt.Color;
import java.awt.EventQueue;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
public class MainFrame extends JFrame {
private JPanel contentPane;
private JTextField textField;
/** * Launch the application. */
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainFrame frame = new MainFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/** * Create the frame. */
public MainFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JDesktopPane desktopPane = new JDesktopPane();
desktopPane.setBackground(Color.LIGHT_GRAY);
desktopPane.setBounds(6, 6, 438, 266);
contentPane.add(desktopPane);
textField = new JTextField();
textField.getDocument().addDocumentListener(new DocumentListener() {
public void changedUpdate(DocumentEvent e) {
}
public void removeUpdate(DocumentEvent e) {
}
public void insertUpdate(DocumentEvent e) {
if (textField.getText().contains(" ")) {
System.out
.println("Space was entered! clearing the text field");
textField.setText("");
}
}
});
textField.setBounds(133, 112, 134, 28);
desktopPane.add(textField);
textField.setColumns(10);
}
}
A DocumentListener is only suitable for notifications to the underlying Document of a JTextComponent. You need a DocumentFilter here
Example
Document listeners should not modify the contents of the document; The change is already complete by the time the listener is notified of the change. Instead, write a custom document that overrides the insertString or remove methods, or both. See Listening for Changes on a Document for details.
(From http://docs.oracle.com/javase/tutorial/uiswing/events/documentlistener.html)
Instead of writing a custom document, I believe it's easier to implement a KeyListener as followed:
JTextField textField = new JTextField();
textField.addKeyListener( new KeyListener() {
#Override
public void keyTyped(KeyEvent arg0) {
if(arg0.getKeyChar() == ' '){
System.out.println("Space was entered! clearing the text field");
textField.setText("");
arg0.consume();
}
}
#Override
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void keyPressed(KeyEvent arg0) {
// TODO Auto-generated method stub
}
Where the arg0.consume() prevents the space from appearing after clearing the textfield
Related
I have a JTextField which needs to be updated from a derived class. So, Used
CLASS TABPANE :
package forstack;
import java.awt.Cursor;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingWorker;
import javax.swing.border.EmptyBorder;
public class TabPane extends JFrame implements ActionListener, propertyChangeListener{
/**
*
*/
private static final long serialVersionUID = 1L;
private JPanel contentPane;
protected JTextField textField;
private Task task;
class Task extends SwingWorker<Void, Void> {
/*
* Main task. Executed in background thread.
*/
#Override
public Void doInBackground() {
Modbus obj = new Modbus();
obj.updatetextfield();
return null;
}
/*
* Executed in event dispatching thread
*/
#Override
public void done() {
setCursor(null); //turn off the wait cursor
//gcsObj.setVisible(false);
}
}
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
TabPane frame = new TabPane();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public TabPane() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JPanel panel = new JPanel();
panel.setBounds(10, 11, 414, 240);
contentPane.add(panel);
panel.setLayout(null);
JButton btnNewButton = new JButton("New button");
btnNewButton.addActionListener(this);
btnNewButton.setBounds(160, 142, 89, 23);
panel.add(btnNewButton);
textField = new JTextField();
textField.setText("Mainclass");
textField.setBounds(119, 61, 175, 20);
panel.add(textField);
textField.setColumns(10);
}
#Override
public void propertyChange(PropertyChangeEvent event) {
// TODO Auto-generated method stub
}
#Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
//Instances of javax.swing.SwingWorker are not reusuable, so
//we create new instances as needed.
task = new Task();
task.addPropertyChangeListener(this);
task.execute();
}
}
CLASS MODBUS :
package forstack;
public class Modbus extends TabPane{
/**
*
*/
private static final long serialVersionUID = 1L;
public void updatetextfield() {
// TODO Auto-generated method stub
textField.setText("hello im here");
textField.revalidate();
textField.repaint();
System.out.println(textField.getText());
}
}
OUTPUT FRAME:
I got the output in the console as "hello im here" but it's not visible in the GUI..
Anyone help me with this issue ..
Check that you don't have 2 different JTextField instances.
Try renaming the JTextFields variables to have different names.
Looks like you're updating the one that's not showing on GUI.
This is the code.
The button doesnt work with key, if i dont click it first. It would
be great if you could help me.
I used eclipse when i created this frame
This is just an example code, but I just want to know how it functions
For any more detalis, ask here.
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JTextField;
public class ExampleApp {
private JFrame frmHi;
private JTextField textField;
private JButton btnAnother;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ExampleApp window = new ExampleApp();
window.frmHi.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public ExampleApp() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmHi = new JFrame();
frmHi.setTitle("Hi");
frmHi.setBounds(100, 100, 450, 300);
frmHi.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmHi.getContentPane().setLayout(null);
JButton btnEnter = new JButton("Enter");
btnEnter.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
textField.setText("You pressed enter");
}
}
});
btnEnter.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText("Hi there from button");
}
});
btnEnter.setBounds(119, 63, 89, 23);
frmHi.getContentPane().add(btnEnter);
textField = new JTextField();
textField.setEnabled(false);
textField.setEditable(false);
textField.setBounds(108, 30, 173, 20);
frmHi.getContentPane().add(textField);
textField.setColumns(10);
btnAnother = new JButton("Backspace");
btnAnother.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent arg0) {
if (arg0.getKeyCode() == KeyEvent.VK_BACK_SPACE){
textField.setText("you pressed backspace");
}
}
});
btnAnother.setBounds(119, 119, 89, 23);
frmHi.getContentPane().add(btnAnother);
}
}
Your KeyListener addded to JButton so it works only when the button has focus (after click).
It's better to define KeyBindings for the keys you have to process.
I use this Java code for demonstration (Just created using eclipse)
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class executor extends JFrame {
private JPanel contentPane;
private JTextField textField;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
executor frame = new executor();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public executor() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
final JLabel lblNewLabel = new JLabel("New label");
contentPane.add(lblNewLabel, BorderLayout.NORTH);
textField = new JTextField();
textField.addKeyListener(new KeyAdapter() {
#Override
public void keyTyped(KeyEvent e) {
lblNewLabel.setText(textField.getText());
}
});
contentPane.add(textField, BorderLayout.CENTER);
textField.setColumns(10);
}
}
and if you type anything into the textfield the label shows everything exactly except prior to the last
Buttonpress. Is there any way to fix that? thank you!
The text field contents change only after the key listener is notified. Instead of trying to track key presses, it is better to listen to the changes in the contents of the text field. This ensures that you also catch changes made by other means, such as cut and paste. The interface for doing that is DocumentListener:
textField.getDocument().addDocumentListener(new DocumentListener() {
#Override
public void removeUpdate(DocumentEvent e) {
lblNewLabel.setText(textField.getText());
}
#Override
public void insertUpdate(DocumentEvent e) {
lblNewLabel.setText(textField.getText());
}
#Override
public void changedUpdate(DocumentEvent e) {
}
});
I am trying to open the menu frame using a button on the main frame. I added an event to the button and I tried calling the other class but it keeps giving me an error of ":: expected after this token"
This is my main frame
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Main extends JFrame {
public static JPanel mainPane;
public final JButton menuButton = new JButton("New button");
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Main frame = new Main();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Main() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
mainPane = new JPanel();
mainPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(mainPane);
mainPane.setLayout(null);
menuButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Menu.main(String[] args);
}
});
menuButton.setBounds(76, 89, 104, 32);
mainPane.add(menuButton);
}
}
And this is my menu frame
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
public class Menu extends JFrame {
public static JPanel menuPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Menu frame = new Menu();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Menu() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
menuPane = new JPanel();
menuPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(menuPane);
menuPane.setLayout(null);
JLabel menuTitle = new JLabel("Menu");
menuTitle.setBounds(194, 11, 46, 14);
menuPane.add(menuTitle);
}
}
change your action event to this.no need to call main method .create a new instance of Menu class instead.
menuButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Menu menu = new Menu();
menu.setVisible(true);
}
});
if you relly want to call main method then use
menuButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Menu.main(new String[0]);
}
});
the error is here
Menu.main(String[] args);//error
this is not a correct way of passing arguments to a methods.this is declaration of parameter list.
you can correct error by changing it to ,
String args[] = null;
Menu.main(args); //correct
I am trying to implement a swing frame. In this, I want to display a processing status in a textPanel using a different thread while performing the needed task. I tried the following code. Of course there is something wrong with the logic. Please provide me with the proper approach
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class SampleSwing {
private JFrame frame;
public static JTextField textField;
public static boolean processing=false;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SampleSwing window = new SampleSwing();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public SampleSwing() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
textField = new JTextField();
textField.setBounds(0, 31, 434, 20);
frame.getContentPane().add(textField);
textField.setColumns(10);
JButton btnNewButton = new JButton("New button");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
processing=true;
Processingstatus ps=new Processingstatus();
ps.start();
/*perform the actual task*/
processing=false;
}
});
btnNewButton.setBounds(174, 74, 89, 23);
frame.getContentPane().add(btnNewButton);
}
}
class Processingstatus extends Thread{
public void run() {
try {
while(SampleSwing.processing) {
SampleSwing.textField.setText("Processing");
Thread.sleep(1000);
SampleSwing.textField.setText("Processing..");
Thread.sleep(1000);
SampleSwing.textField.setText("Processing...");
Thread.sleep(1000);
}
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
First I thought, "you should be using a SwingWorker, as it has methods to handle progress and EDT updates..."
But when I looked closer, you don't actually really care about the process itself, you just want some where to show that a process is running...They are two separate entities, that are only related because one (the UI updates) will run so long as the other is running.
So, instead, I used a javax.swing.Timer. This allows me to schedule an event to occur every n milliseconds and have that triggered in the EDT, nice and clean...
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingWorker;
import javax.swing.Timer;
public class SampleSwing {
private JFrame frame;
public static JTextField textField;
public static boolean processing = false;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SampleSwing window = new SampleSwing();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public SampleSwing() {
initialize();
}
private Timer processTimer;
private void initialize() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
textField = new JTextField(25);
frame.add(textField, gbc);
processTimer = new Timer(500, new ActionListener() {
private StringBuilder dots = new StringBuilder(3);
#Override
public void actionPerformed(ActionEvent e) {
dots.append(".");
if (dots.length() > 3) {
dots.delete(0, dots.length());
}
textField.setText("Processing" + dots.toString());
}
});
JButton btnNewButton = new JButton("New button");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
if (!processing) {
processing = true;
processTimer.start();
} else {
processTimer.stop();
processing = false;
textField.setText(null);
}
}
});
frame.add(btnNewButton, gbc);
frame.pack();
frame.setLocationRelativeTo(null);
}
}
ps For the reason why your original code didn't work, see my comment in the above comments section ;)