I am building a GWT component to behave much like the comments box here on stackoverflow, and other sites. I am trying to register listeners for KeyPress, Change and ONPASTE events that will update my status line with number of characters remaining, etc.
It works except it is always one character behind the actual number of characters in the text area. I set the max number of characters to 10. When I type the first character it still says, "10 characters remaining". It doesn't update the status line until I type the second character and then it is one off, it says 9 characters remaining when the second character is typed.
When I BACKSPACE or DELETE, it is also one off, when there are no characters it still says "9 characters remaining" until I press the BACKSPACE or DELETE a second time.
I am getting this behavior in both Firefox, Chrome and Internet Explorer on Windows. So I think I am not registering something correctly.
I know this has something to do with when the events are getting fired, but I have spend hours on trying to diagnose this behavior and have run out of ideas.
Here is where I am registering the event handlers, the complete code is BoundedTextAreaWithFeedback.
private void registerHandlers()
{
final BoundedTextAreaWithFeedback outer = this;
this.textArea.addChangeHandler(new ChangeHandler()
{
public void onChange(final ChangeEvent changeEvent)
{
outer.validate();
}
});
this.textArea.addKeyPressHandler(new KeyPressHandler()
{
public void onKeyPress(final KeyPressEvent keyPressEvent)
{
outer.validate();
}
});
this.panel.addFocusHandler(new FocusHandler()
{
public void onFocus(final FocusEvent focusEvent)
{
outer.textArea.setFocus(true);
}
});
// capture paste events
this.textArea.sinkEvents(Event.ONPASTE);
}
Here is the validate() method.
private boolean validate()
{
final boolean isValid;
final int len = this.textArea.getText().length();
if (len < this.minLength)
{
this.status.setText("Enter at least " + this.minLength + " characters.");
this.status.setStyleName("input-status-underflow");
isValid = false;
}
else if (len > this.maxLength)
{
this.status.setText(this.maxLength - len + " characters remaining");
this.status.setStyleName("input-status-overflow");
isValid = false;
}
else
{
this.status.setText(this.maxLength - len + " characters remaining");
this.status.setStyleName("input-status-ok");
isValid = true;
}
return isValid;
}
I just started adding every addXXXHandler() until one worked.
this.textArea.addKeyUpHandler(new KeyUpHandler()
{
public void onKeyUp(final KeyUpEvent event)
{
outer.validate();
}
});
Seems to have done the trick.
Here is the working code, CTRL-V and paste from context menu also work now.
Try using a DeferredCommand to execute the validation code. I believe the problem is that when the event is firing, they character is not yet added to the text area. The DeferredCommand will not execute until any pending event handlers have finished, allowing the length of the text to be calculated correctly.
See this question for an example of using a DeferredCommand.
Related
I'm trying to make a 2d game using java microedition and i just want to make my control smoother but the problem is when i press the LEFT key while pressing the UP Key the condition is not working i dont know why
public void moveJet2() throws IOException{
int gameAction = getKeyStates();
if(gameAction==LEFT_PRESSED && gameAction==UP_PRESSED){
padX-=padXVel;
padY-=padYVel;
}
else if(gameAction==RIGHT_PRESSED){
padX += padXVel;
}
else if(gameAction==UP_PRESSED){
padY-=padYVel;
}
else if(gameAction==DOWN_PRESSED){
padY+=padYVel;
}
}
getKeyStates() returns the state of keys in a single int. The various keys have individual values. UP_PRESSED = 0x0002 and LEFT_PRESSED = 0x0004. So if you press UP on your d-pad while calling getKeyStates(), you'll get 2 back, and if (getKeyStates()==UP_PRESSED) will thus be true.
Likewise, if you press LEFT on your d-pad while calling getKeyStates(), you'll get 4 back.
But if you press UP and LEFT at the same time, you can't get back 2 and 4 - because that's obviously 2 ints - and getKeyStates() only returns one int.
What you do get back though, is rather simple: 2 + 4 = 6.
So, asking if (getKeyStates()==6) will be true if pressing UP and LEFT at the same time. Or if (getKeyStates()==UP_PRESSED+LEFT_PRESSED).
Typically though, you would ask using bit-operators, like this:
public void moveJet2() throws IOException{
int gameAction = getKeyStates();
if((gameAction & LEFT_PRESSED)!=0) {
padX -= padXVel;
}
if((gameAction & RIGHT_PRESSED)!=0) {
padX += padXVel;
}
if((gameAction & UP_PRESSED)!=0) {
padY-=padYVel;
}
if((gameAction & DOWN_PRESSED)!=0){
padY+=padYVel;
}
}
Because using that approach will work with any of the 8 directions you can press at the same time.
Below is the code I'm using to add an OnKeyboardActionListener to my KeyboardView. (For the sake of brevity, I've omitted the required overridden methods that I've left empty.)
keyboardView.setOnKeyboardActionListener(new OnKeyboardActionListener() {
private void shiftOn(boolean on) {
System.out.println("Shifting " + (on ? "on" : "off"));
keyboard.setShifted(on);
shiftKey.icon = keyboard.isShifted() ? shiftLockDrawable : shiftDrawable;
}
#Override
public void onKey(int primaryCode, int[] keyCodes) {
Editable editable = editText.getEditableText();
int selectionStart = editText.getSelectionStart();
if (primaryCode == SHIFT) {
shiftOn(!keyboard.isShifted());
} else {
if (primaryCode == DELETE) {
if (editable != null && selectionStart > 0) {
editable.delete(selectionStart - 1, selectionStart);
}
} else {
editable.insert(selectionStart, Character.toString((char) primaryCode));
}
shiftOn(false);
}
}
});
The problem
When I press the shift key, everything goes as expected; both the key's icon and the state of "shiftedness" changes.
However, when I press any other key (which is supposed to turn shift off), the state of shiftedness changes to off, but the icon doesn't change to the unshifted version. I experience the same problem when using text instead of icons.
I've tried calling postInvalidate() on my KeyboardView but to no avail.
Here's a video that highlights my problem.
I added the following code to the end of the shiftOn method:
keyboard.invalidateKey(SHIFT);
It seems to me that the redrawing of the shift key is attached to the actual input event. Can you, instead of changing the shiftKeyIcon simulate a shift key press in code? You just generate an additional shift key press event when another key is pressed.
I hope this helps you.
I think that there is a problem in shiftOn(). I don't exactly know what shiftLockDrawable and shiftDrawable do, but maybe the following code works
private void shiftOn(boolean on) {
System.out.println("Shifting " + (on ? "on" : "off"));
shiftKey.icon = (on ? shiftLockDrawable : shiftDrawable);
keyboard.setShifted(on);
}
If this doesn't work or if this isn't what you want, could you maybe provide more information?
I found some good Q/A here on my problem but couldn't find the right one.
I have a barcode reader that reads barcode and sends scanned code as keyboard input. It is alright I can catch input easily
browser.addKeyListener(new KeyAdapter() {
#Override public void keyPressed(KeyEvent e) {
if(e.keyCode >=48 && e.keyCode <=57) {
System.out.println("number caught");
}
}
});
But I will have more inputs in my application so I need to know if it is send by barcode reader or by keyboard.
I think it can be achieved by adding some timer in code that verifies how long is some "sequence" reading.
I just can not figure it out, (I mean logic behind it), I am missing piece of logic.
User is typing some info, (alpha numerical)
user desides to use barcode reader to read barcode
I tried timer e.g
if(System.currentTimeMillis() - lastPressProcessed ??? 500) { after keyListener is triggered but I think I am missing something.
sidenote:
USB barcode reads code fast so keystrokes are emulated really fast est whole barcode is written in about 1 second + carry /r/n (also enter is pressed).
sidenote2: barcodes are going to be different in length so I can not read just some length in short time and decide wether it is user input or barcode input (max numbers read 13 + enter).
sidenote3: I have no input field for barcode I am trying to achieve running it on "background".
I am seeking logic/pseudocode suggestions on topic.
related topics that are really close to mine are here, and here
Thank you.
edit
After deep tought I found out the solution I'll keep this Q here just for another users that might find this usable.
solution
--moved to answer + edited
This code coveres everything I wanted to achieve, it reads just numbers (actualy numbers that are under F keys, not numbers that are on numpad, I had problem with it because scanner is keyboard dependant so I made function signsToNumbers() that converts signs !##$%^&*() to numbers 1234567890. I may change this function because every key on keyboard has its own unique identifier + modifier, it seems that scanner sends also SHIFT modifier to the application but that is not as problem as it seems I'll just match e.keyCode.
The code below works as:
waits for number input otherwise does nothing
if 1st number is inserted it is looping in if condition until either 200ms is reached or '\r\n` is received
sends data to server via URL
code
#Override public void keyPressed(KeyEvent e) {
if (timer == true && System.currentTimeMillis() - lastTimer < 200) {
if(e.keyCode >=48 && e.keyCode <=57) { //number pressed
lastTimer = System.currentTimeMillis();
myString = myString + Character.toString(e.character);
}
if(e.keyCode == SWT.CR) {
myString = signsToNumbers(myString);
newUrl = browser.getUrl()+ "/newcode/" + myString;
browser.setUrl(newUrl);
text.setText(newUrl);
System.out.println(myString);
System.out.println("barcode read");
myString = "";
timer = false;
lastTimer = 0;
}
}else{
if(e.keyCode >=48 && e.keyCode <=57) {
lastTimer = System.currentTimeMillis();
timer = true;
myString = Character.toString(e.character);
}
myString = "";
lastTimer = 0;
}
}
});
Here you can download my solution:
http://jhead.hu/resource/java/general/BarcodeReader.java
The following code sample shows you, how to use it. When a new barcode is identified, an ActionEvent is generated and you can get the barcode via the getActionCommand() method. If the panel is not active you can send the characters further to the focus manager.
The only problem is that my barcode scanner sends the characters too fast so the character bits are sometimes mixed. I've got no better solution yet.
public class PanelWithBarcodeReading extends javax.swing.JPanel implements ActionListener {
private BarcodeReader barcodeReader = new BarcodeReader();
public PanelWithBarcodeReading() {
initComponents();
barcodeReader.addActionListener(this);
barcodeReader.setParent(this);
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(barcodeReader);
}
#Override
public void actionPerformed(ActionEvent e) {
if (SwingUtilities.getWindowAncestor(this).isActive()) {
System.out.println("BARCODE='" + e.getActionCommand() + "'");
} else {
barcodeReader.dispatchLastBarcodeAsKeyEvents();
}
}
...
}
Outside of the actual SWT listener, is there any way to ignore a listener via code?
For example, I have a java program that implements SWT Text Widgets, and the widgets have:
SWT.Verify listeners to filter out unwanted text input.
ModifyListeners to wait for the correct number of valid input characters and automatically set focus (using setFocus())to the next valid field, skipping the other text widgets in the tab order.
focusLost(FocusEvent) FocusListeners that wait for the loss of focus from the text widget to perform additional input verification and execute an SQL query based on the user input.
The issue I run into is clearing the text widgets. One of the widgets has the format "####-##" (Four Numbers, a hyphen, then two numbers) and I have implemented this listener, which is a modified version of SWT Snippet Snippet179. The initial text for this text widget is " - " to provide visual feedback to the user as to the expected format. Only numbers are acceptable input, and the program automatically skips past the hyphen at the appropriate point.
/*
* This listener was adapted from the "verify input in a template (YYYY/MM/DD)" SWT Code
* Snippet (also known as Snippet179), from the Snippets page of the SWT Project.
* SWT Code Snippets can be found at:
* http://www.eclipse.org/swt/snippets/
*/
textBox.addListener(SWT.Verify, new Listener()
{
boolean ignore;
public void handleEvent(Event e)
{
if (ignore) return;
e.doit = false;
StringBuffer buffer = new StringBuffer(e.text);
char[] chars = new char[buffer.length()];
buffer.getChars(0, chars.length, chars, 0);
if (e.character == '\b')
{
for (int i = e.start; i < e.end; i++)
{
switch (i)
{
case 0: /* [x]xxx-xx */
case 1: /* x[x]xx-xx */
case 2: /* xx[x]x-xx */
case 3: /* xxx[x]-xx */
case 5: /* xxxx-[x]x */
case 6: /* xxxx-x[x] */
{
buffer.append(' ');
break;
}
case 4: /* xxxx[-]xx */
{
buffer.append('-');
break;
}
default:
return;
}
}
textBox.setSelection(e.start, e.start + buffer.length());
ignore = true;
textBox.insert(buffer.toString());
ignore = false;
textBox.setSelection(e.start, e.start);
return;
}
int start = e.start;
if (start > 6) return;
int index = 0;
for (int i = 0; i < chars.length; i++)
{
if (start + index == 4)
{
if (chars[i] == '-')
{
index++;
continue;
}
buffer.insert(index++, '-');
}
if (chars[i] < '0' || '9' < chars[i]) return;
index++;
}
String newText = buffer.toString();
int length = newText.length();
textBox.setSelection(e.start, e.start + length);
ignore = true;
textBox.insert(newText);
ignore = false;
/*
* After a valid key press, verifying if the input is completed
* and passing the cursor to the next text box.
*/
if (7 == textBox.getCaretPosition())
{
/*
* Attempting to change the text after receiving a known valid input that has no results (0000-00).
*/
if ("0000-00".equals(textBox.getText()))
{
// "0000-00" is the special "Erase Me" code for these text boxes.
ignore = true;
textBox.setText(" - ");
ignore = false;
}
// Changing focus to a different textBox by using "setFocus()" method.
differentTextBox.setFocus();
}
}
}
);
As you can see, the only method I've figured out to clear this text widget from a different point in the code is by assigning "0000-00"
textBox.setText("000000")
and checking for that input in the listener. When that input is received, the listener changes the text back to " - " (four spaces, a hyphen, then two spaces).
There is also a focusLost Listener that parses this text widget for spaces, then in order to avoid unnecessary SQL queries, it clears/resets all fields if the input is invalid (i.e contains spaces).
// Adding focus listener to textBox to wait for loss of focus to perform SQL statement.
textBox.addFocusListener(new FocusAdapter()
{
#Override
public void focusLost(FocusEvent evt)
{
// Get the contents of otherTextBox and textBox. (otherTextBox must be <= textBox)
String boxFour = otherTextBox.getText();
String boxFive = textBox.getText();
// If either text box has spaces in it, don't perform the search.
if (boxFour.contains(" ") || boxFive.contains(" "))
{
// Don't perform SQL statements. Debug statement.
System.out.println("Tray Position input contains spaces. Ignoring.");
//Make all previous results invisible, if any.
labels.setVisible(false);
differentTextBox.setText("");
labelResults.setVisible(false);
}
else
{
//... Perform SQL statement ...
}
}
}
);
OK. Often, I use SWT MessageBox widgets in this code to communicate to the user, or wish to change the text widgets back to an empty state after verifying the input. The problem is that messageboxes seem to create a focusLost event, and using the .setText(string) method is subject to SWT.Verify listeners that are present on the text widget.
Any suggestions as to selectively ignoring these listeners in code, but keeping them present for all other user input?
Thank you in advance for your assistance.
If you name the listener instead of using an anonymous one, you can add and remove it whenever you like.
Example:
// Adding focus listener to textBox to wait for loss of focus to perform SQL statement.
FocusAdapter focusTextBox = new FocusAdapter()
{
#Override
public void focusLost(FocusEvent evt)
{
// Get the contents of otherTextBox and textBox. (otherTextBox must be <= textBox)
String boxFour = otherTextBox.getText();
String boxFive = textBox.getText();
// If either text box has spaces in it, don't perform the search.
if (boxFour.contains(" ") || boxFive.contains(" "))
{
// Don't perform SQL statements. Debug statement.
System.out.println("Tray Position input contains spaces. Ignoring.");
//Make all previous results invisible, if any.
labels.setVisible(false);
differentTextBox.setText("");
labelResults.setVisible(false);
}
else
{
//... Perform SQL statement ...
}
}
};
You can then add the listener by doing this:
textBox.addFocusListener(focusTextBox);
Removal is as easy as this:
textBox.removeFocusListener(focusTextBox);
Just make sure to re-enable the listener after you've done what you've wanted to programmatically achieve, or your code will not act like you'd expect.
I didn't tested your code, but try method isFocusControl() in the listener to see if the user enters the text or you set the text with setText() when the focus is not in textBox.
I'm trying to learn something about GUI, using NetBeans6.8, starting with the GUI section in The java tutorial.
There is a simple exercise for a Celsius-Fahrenheit converter. I want that to have two TextFields, one for Celsius and one for Fahrenheit temperature; if the user types in the celsius text field he got the result "printed" in the fahrenheit text filed. and vice versa.
So, i put on both the textfields one KeyTyped event, here's the code:
private void celsiusTextKeyTyped(java.awt.event.KeyEvent evt) {
int cels = Integer.parseInt(celsiusText.getText());
int fahr = (int)(cels * 1.8 + 32);
fahrText.setText(fahr + "");
}
private void fahrTextKeyTyped(java.awt.event.KeyEvent evt) {
int fahr = Integer.parseInt(fahrText.getText());
int cels = (int)(fahr / 1.8 - 32);
celsiusText.setText(cels + "");
}
It doesn't work. If i type something in a textfield i got this exception: java.lang.NumberFormatException: For input string: ""
The code that attach the listeners:
celsiusText.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyTyped(java.awt.event.KeyEvent evt) {
celsiusTextKeyTyped(evt);
}
});
fahrText.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyTyped(java.awt.event.KeyEvent evt) {
fahrTextKeyTyped(evt);
}
});
[However, i can't modify it, it's autogenerated.]
Method .getText() returns a string not a number, if that string contains non-numeric characters (i.e. a letter, a space, nothing at all) then parseInt will throw a NumberFormatException. Since your using KeyEvent, as soon as you press say "7", the event is fired before 7 is entered into the text box. Thus the text box still only contains "", which is where the error comes from. You may wish to also listen to the keyUp event instead.
You need to enclose your code in a try catch block.
private void fahrTextKeyTyped(java.awt.event.KeyEvent evt)
{
try
{
int fahr = Integer.parseInt(fahrText.getText());
int cels = (int)(fahr / 1.8 - 32);
celsiusText.setText(cels + "");
}
catch(NumberFormatException ex)
{
//Error handling code here, i.e. informative message to the user
}
}
An alternative is you could filter out non-numbers on keydown event, see example here - http://www.javacoffeebreak.com/java107/java107.html (Creating a custom component - NumberTextField)
I suspect that what's happened is that you added these handlers with something like celsiusText.addKeyListener, yes?
The thing is, that'll give you not just the KEY_TYPED events you wanted, but also KEY_DOWN and KEY_UP. The KEY_DOWN event will happen before the text is really entered into the field, so your code firing on that will see the field as blank still. Trying to convert the empty string to a number gives you a format exception.
The easiest way to fix this is the try/catch construct other people have been posting.
You probably set action to keyDown, this mean that even occur before the key value is "added" to textbox, while You retrieve the value from it is still empty "".
There is a simple exercise for a
Celsius-Fahrenheit converter
That is a really old example. The better approach is to use a DocumentListener, not a KeyListener.