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Transfer cursor to JTextField when press JButton

When I click on the "Preview Page" button, the cursor should move to the Start Position (txtStartPosition). Below is my code that I wrote but somehow it is not working.
btnPreviewPage = new JButton("Preview Single");
btnPreviewPage.setFocusable(false);
btnPreviewPage.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
txtStartPosition.setCaretPosition(txtStartPosition.getCaretPosition() - 1);
new UIPreviewPage().execute();
}
});
panel.add(btnPreviewPage, "cell 1 18,alignx right");

You need to do JTextField.requestFocus();or, the more preferred JTextField.requestFocusInWindow();
https://docs.oracle.com/javase/7/docs/api/javax/swing/JComponent.html#requestFocus()
public void requestFocus()
Requests that this Component gets the input focus. Refer to Component.requestFocus() for a complete description of this method.
Note that the use of this method is discouraged because its behavior is platform dependent. Instead we recommend the use of requestFocusInWindow(). If you would like more information on focus, see How to Use the Focus Subsystem, a section in The Java Tutorial.
Overrides:
requestFocus in class Component
Since:
1.4
See Also:
Component.requestFocusInWindow(), Component.requestFocusInWindow(boolean)
Using your code it should be
tnPreviewPage = new JButton("Preview Single");
btnPreviewPage.setFocusable(false);
btnPreviewPage.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
//Add YourJTextField.requestFocusInWindow() here, but not sure if the other information is needed
txtStartPosition.setCaretPosition(txtStartPosition.getCaretPosition() - 1);
new UIPreviewPage().execute();
}
});
panel.add(btnPreviewPage, "cell 1 18,alignx right");

How to change the default cursor position of a JTextArea?

In previous question I asked how to set cursor to the bottom of the JTextArea. The answer was textField.getDocument().getLength() Technically, I can use textField.getDocument().getLength() after every text insert, but this is not convenient.
However, this is not exactly what I meant. I need to change the JTextArea PROPERTY of cursor position. In my program _result is JTextArea. It gets texts from multiple classes and methods, so using textField.getDocument().getLength() everytime after _result.append("text") is not convenient and makes code error prone and not flexible
Is there any way I could do something like:
// this is just a pseudocode
_result.setDefaultCursorPosition(bottom);
and then whenever text goes there (NO MATTER from what class or method), the cursor is always at the bottom.

This would move the caret to the end position after each document change:
_result.getDocument().addDocumentListener(new DocumentListener() {
private void atEnd() {
_result.setCaretPosition(_result.getText().length());
}
public void insertUpdate(DocumentEvent evt) { atEnd(); }
public void removeUpdate(DocumentEvent evt) { atEnd(); }
public void changedUpdate(DocumentEvent evt) { atEnd(); }
});
It still allows the user to re-position the caret by clicking, or by other calls to setCaretPosition.

How can I Listen for Keyboard input without Text Field Java

I am working on a Java application and interfacing with an RFID reader that acts as a keyboard input device.
The application will be used for employee time tracking, so the employee should not see the code that his/her RFID tag contains.
Currently, the application opens a jFrame that asks the employee to scan their tag. This is where I would like to listen for the keyboard input.
All of the RFID tags are 10 digits, so I would like to use some kind of regex to detect when a card is scanned if possible.
If someone could point me in the right direction, or contribute some code I would be grateful.
Thanks in advance.
UPDATE:
I was able to read the input of the scanner by adding the following to the constructor of my JFrame.
addKeyListener(new KeyListener(){
#Override
public void keyPressed(KeyEvent e){ System.out.print(e.getKeyChar());}
#Override
public void keyReleased(KeyEvent e) { }
#Override
public void keyTyped(KeyEvent e) { }
});
So it is now confirmed that the Reader is just standard Keyboard input.
Here is an example of what I get for a tag: 0006459027
Now, the big question is, how do I take the characters that I got, and detect that it is a 10 digit string, and from there trigger an event to open a new frame?

First, I'd see if the RFID reader is triggering an ActionEvent to be fired when the tag is scanned. This would be the simplest approach.
Failing that, you would need to attach a DocumentListener to the fields underlying document and monitor for changes.
You'll need to decide how best to interrupt the results (as you're likely to get each letter of the RFID at a time). You could monitor the length of the document or have a javax.swing.Timer which triggers after a short delay (you'd reset the timer on each update event triggered by the DocumentListener)
Check out
JTextField.addActionListener
JTextField.getDocument().addDocumentListener
I'd suggest taking a look at DocumentFilter as well, but your interested in the final result, not modifying it.
UPDATED with DocumentListener Example
// In the classes variable decleration section...
private JTextField rfidField;
// In the classes constructor or UI init method...
rfidField = new JTextField(12);
rfidField.getDocument().addDocumentListener(new DocumentListener() {
public void handleUpdate(DocumentEvent e) {
if (e.getDocument().getLength() == 10) {
System.out.println("Trigger me happy...");
SwingUtilities.invokeLater(new Runnable() {
public void run() {
rfidField.setText(null);
}
});
}
}
#Override
public void insertUpdate(DocumentEvent e) {
handleUpdate(e);
}
#Override
public void removeUpdate(DocumentEvent e) {
handleUpdate(e);
}
#Override
public void changedUpdate(DocumentEvent e) {
handleUpdate(e);
}
});
// Now don't forget to add the field to your forms container ;)
//////
One of things I would be do when you "trigger" the code event is, once you've read it from the text field, is clear the text field (JTextField.setText(null)) - IMHO

If the RFID reader acts as a keyboard input device, try with key events:
JFrame frame = new JFrame();
// frame setup
frame.addKeyListener(new KeyAdapter(){
public void KeyPressed(KeyEvent ke)
{
System.out.println(ke);
}
});
Otherwise you have to check which kind of event it fires.

I was in a similar situation but with a bar-code scanner.
I really worked hard on a custom DocumentListener that would take care of all scenarios, and none of it worked.
Out of desperation, I added an ActionListener and it then worked very well.
Here is a code snap-shot :
try {
txtStockItemRef.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
System.out.println(txtStockItemRef.getText());
DatabaseManager.peformStockItemLookupByBarcodeRef(txtStockItemRef.getText());
}
});
} catch(Exception exc) {
LiveCityRetailTools.handleExceptionWithUserMessage(exc);
}

JTable won't listen to Doubleclicks

I´m trying to implement an undo (and redo) function for an editable JTable with the default components. The JTable has an extra class to specify its properties called SpecifiedJTable.
To do so I wanted to grab the moment when a cell is doubleclicked (i.e. the moment when a cell is chosen/marked to be edited) to push the information in the cell and its coordinates onto the stack.
This should be done by a MouseListener ...at least that was my idea.
I tried this (standing in the constructor of my SpecifiedJTable class)
class JTableSpecified extends JTable {
private static final long serialVersionUID = 1L;
private int c; // the currently selected column
private int r; // the currently selected row
public JTableSpecified(String[][] obj, String[] columnNames) {
super(obj, columnNames); // constructs the real table
// makes that you can only select one row at a time
this.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
// makes that columns are not squeezed
this.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
// forbids to rearrange the columns
getTableHeader().setReorderingAllowed(false);
// adds action listener
this.getModel().addTableModelListener(new TableModelListener() {
public void tableChanged(TableModelEvent e) {
r = getSelectedRow();
c = getSelectedColumn();
// get the String at row r and column c
String s = (String) getValueAt(r, c);
if (jobDisplayed) jobSwitch(c, s);
else resSwitch(c, s);
}
});
this.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (e.getClickCount() == 2) {
System.out.println("test");
}
}
});
}
}
but somehow the clickCounter doesn´t want to reach anything that´s higher than 1.
I am glad about any answer and help. Thanks.

The problem you are experiencing is related to use of mouseClicked() rather than using mousePressed(). In this case it appears to be very hard to increase the click counter, yet still it is possible. It took me lots of clicking and also mouse movement to increase the click counter over 1. You could try it by yourself, in your code. To get the counter over 1 you need to go crazy on the mouse by pressing & releasing fast while moving the mouse from cell to cell at the same time (or maybe I was just luckily clicking between the cells?).
As you can see in this fully working sample, made from your code, two mouse presses, using the mousePressed() method are being detected just fine.
public class JTableSpecified extends JTable {
private static final long serialVersionUID = 1L;
public JTableSpecified(String[][] obj, String[] columnNames) {
super(obj, columnNames); // constructs the real table
// makes that you can only select one row at a time
this.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
// makes that columns are not squeezed
this.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
// forbids to rearrange the columns
getTableHeader().setReorderingAllowed(false);
// adds action listener
this.getModel().addTableModelListener(new TableModelListener() {
#Override
public void tableChanged(TableModelEvent e) {
}
});
this.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
if (e.getClickCount() == 2) {
System.out.println("test");
}
System.out.println("e.getClickCount() = " + e.getClickCount());
}
});
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JPanel panel = new JPanel();
panel.add(new JTableSpecified(new String[][]{{"oi", "oi2"}, {"oi3", "oi4"}}, new String[]{"Col1", "Col2"}));
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(panel);
f.pack();
f.setVisible(true);
}
});
}
}
Conclusion: Maybe you in fact want to use the mousePressed() method?

This answer extends Boro´s answer.
To catch every case that enables the user to edit the table I will also need to add a KeyListener for F2 (which has the same effect as double clicking onto a cell) and disable the automatic cell editing by pressing any key.
I just added it to the constructor right behind the mouseListener (see above)
// forbids the editing by striking a key
this.putClientProperty("JTable.autoStartsEdit", Boolean.FALSE);
// keyListener to react on pressing F2 (key code 113)
this.addKeyListener(new KeyAdapter(){
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == 113) System.out.println("test");
}
});

The BasicTableUI is responding to the double-click by going into an edit mode on the cell that was double-clicked. It does lots of complicated stuff, part of which involves creating a JTextField (or other component) to allow the data to be edited, and then preventing the mouse click event from propagating any further.
If your table, or that table cell, is not editable, you can easily capture mouse events with click count 2, 3, 4, .... But since you want your table to be editable, you need a different approach.
One idea would be to override JTable.editCellAt()
A better idea is to forget about messing with the JTable and instead listen for data changes on the table model itself.

the error in the code is that the mouseClicked method is called as soon as the first click takes place. when a double click takes place the mouseClicked method is called again. you can place a static variable (or a class variable) for the earlier click event storing the time (using the e.getWhen() method).
Check for the time difference and if it's small enough, execute your actions (I'd suggest calling a doubleClick method).
you may have to implement mouse listener in your class JTableSpecified since a static variable might not be placed in your existing code.

Java KeyListener not firing on JSpinner

have tried a few different approaches to this but with no success so far. Just wondered if I'm missing anything. I have a JSpinner which is a component of a DateSelector widget alongside a Calendar. I am trying to fire a validation method if the user changes any text in the JSpinner instead of using the Calendar control or the JSpinner up and down arrows.
Here are the different approaches I have tried:
jSpinner1.addKeyListener(kl);
jSpinner1.getEditor().addKeyListener(kl);
((JSpinner.DefaultEditor) jSpinner1.getEditor().getTextField().addKeyListener(kl);
Anyone out there got any ideas as to what I'm doing wrong? Thanks
UPDATE
Apologies, I should have said that I have already added a ChangeListener to the JSpinnerDateModel which is attached to the JSpinner. Like so:
ChangeListener changeListener = new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
dateChanged();
}
};
jSpinnerDateModel.addChangeListener(changeListener);
KeyListener keyListener = new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println(e.getKeyChar());
dateChanged();
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
};
((JSpinner.DefaultEditor) jSpinner1.getEditor()).getTextField().addKeyListener(
keyListener);
Thanks
Frank

If you want to disable keyboard editing do this:
JFormattedTextField tf = ((JSpinner.DefaultEditor)spinner.getEditor()).getTextField();
tf.setEditable(false);
To listen for key events you need to add a listener to the text field. This works for me:
((JSpinner.DefaultEditor)spinner.getEditor()).getTextField().addKeyListener(new KeyListener(){
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println("PRESSED!");
}
#Override
public void keyTyped(KeyEvent e) {
}
});

JSpinners handle KeyEvents themselves, but they fire ChangeEvents to the outside world. Adding a ChangeListener should allow you to perform the validation you wish.
See also: Detecting Spinner Value Changes (Java Tutorials)

This is a shortfall of swing, and in my opinion JSpinner should follow JComboBox in supplying the following access to the underlying text field:
JComboBox.getEditor().getEditorComponent()
From going through the source of J1.7 I found you can acheive pretty much the same thing with
JSpinner.getEditor().getComponent(0)
Therefore you can "hack" the listener in the following way:
JSpinner.getEditor().getComponent(0).addKeyListener(...)
Obviously this depends on the 'under the covers' implementation of swing and works as at J1.7 but there is no guarantee this works for other versions future or past.
Enjoy.
EDIT
or if the editor is an instance of DefaultEditor, you can cast it as such and use 'getTextField()'. It would be handy if this were defined in the interface.