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.
Related
hi i am trying to build a grid-layout GUI with mouse listener. SO when a particular cell is clicked in a grid ,information would be displayed. I don't know where to start, any help would be good
thankyou
I believe you have a class that inherits from JPanel or JFrame and there is whole GUI in it. Then, this class should implement mouseListener. Then your class should have similar code:
#override
public void mouseClicked(MouseEvent e){}
#override
public void mousePressed(MouseEvent e){}
#override
public void mouseEntered(MouseEvent e){}
#override
public void mouseReleased(MouseEvent e){
/*This method is being called when you release your click. It's better
then mouseClicked because mouseClicked is only called when you press
and release on the same pixel or Object (not sure about it)
*/
}
#override
public void mouseExiteded(MouseEvent e){}
In each method you can get source of
MouseEvent e
using
Object source = e.getSource();
if (source == button1){
//Do sth
}if (source == button2){
//Do sth else
}if (source == radioButton1){
//Do whatever you want
}
Then you have reference to the source, so you can modify what you want.
In your gridlayout, set all grids with some Component such as Button or Label. You can set listeners on the components added and display information when a component is clicked
To use properly a gridbaglayout, you should first work on the gridbagconstraints. Then, you should use the ActionListener interface to handle the mouse clicks. If the cells are of the type Labels, you coud hide the text by using myLabel.setText("") and putting the text by using myLabel.setText("information to display"). If you need more help, just ask :D and +1 if it helps ^^
I am learning java and Swing right now and trying to develop simple programms for education purposes.
So here is the question.
I have gridlayout and fields on my frame with default text
accNumberField = new JTextField("0", 10);
accNumberField.addFocusListener(new FocusListener() {
int focusCounter = 0;
#Override
public void focusGained(FocusEvent arg0) {
// TODO Auto-generated method stub
if (focusCounter > 0)
accNumberField.setText("");
focusCounter++;
}
What I want is that when user click on field for the first time the default text is disappered. So I add focus listener and used accNumberField.setText(""); in focusGained method.
But the problem is that for default first field in my frame getting focus right in time of frame creation. And default text is disappearing from the begining. I used counter as you can see. But that's not what I wanted.
I want that no field would get focus in time of creation and every field would be able to get focus from the time when user would click on one of them.
Sorry if I spelled something wrong. English is not my native language.
Found a thread having a code example of your desired functionality, Java JTextField with input hint. Precisely, you need to provide your own implementation of JTextField which will be holding the "default-text" in a field, specially created for that.
For your second question, you can set the focus to some button or frame itself.
Is there any reason that you use focusListener()? why not use mouseListener() as follow?
accNumberField.addMouseListener(new MouseAdapter()
{
#Override
public void mouseReleased(MouseEvent e)
{
accNumberField.setText("");
}
});
if you want to clear the text for the first click, you can simply use a boolean:
//outside constructor
private boolean isTextCleared = false;
//in constructor
accNumberField.addMouseListener(new MouseAdapter()
{
#Override
public void mouseReleased(MouseEvent e)
{
if (!isTextCleared)
{
accNumberField.setText("");
isTextCleared = true;
}
}
});
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);
}
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.
I'm having some problems I just can't figure out...
I'm writing a Swing Java application with a JList that accepts drag-and-drops. I want to change the cursor while dragging a file or folder from my system over the Java application.
I've found it myself... Thanks Clinton for answering though. Here's what I've used:
first create the JList... You all know how to do that...
Then I've added a setDropTarget:
lstFiles.setDropTarget(new DropTarget()
{
#Override
public synchronized void drop(DropTargetDropEvent dtde)
{
this.changeToNormal();
//handle the drop... [...]
}
#Override
public synchronized void dragEnter(DropTargetDragEvent dtde)
{
//Change cursor...
Cursor cursor = new Cursor(Cursor.HAND_CURSOR);
setCursor(cursor);
//Change JList background...
lstFiles.setBackground(Color.LIGHT_GRAY);
}
#Override
public synchronized void dragExit(DropTargetEvent dtde)
{
this.changeToNormal();
}
private void changeToNormal()
{
//Set cursor to default.
Cursor cursor = new Cursor(Cursor.DEFAULT_CURSOR);
setCursor(cursor);
//Set background to normal...
lstFiles.setBackground(Color.WHITE);
}
});
The following will only change the cursor when the user has moved the mouse over your JList.
You can change the cursor when you mouse over a component (i.e. your JList) by using a mouse listener and the setCursor method.
Essentially just add the mouse listener to your JList and use setCursor to change the cursor when the user mouses over the component in your application (mouseEntered and mouseExit). You may also need to do a little inquiry on your drag and drop code to only change the cursor when something valid is being dragged into your JList.
Hope this helps a bit.