I'm making a small app where I have two text fields. But I want it to be that when the user insert something that is not a number, it gives an alert message. I have done it like below but it does not work. I have tried tp use try & catch. Can anyone help me with this?
public void actionPerformed(ActionEvent ngjarja)
{
String rresht = teksti1.getText();
int rreshtii = Integer.parseInt(rresht);//kthimi i stringut ne integer
String shtyll = teksti2.getText();
int shtylle = Integer.parseInt(shtyll);
if (ngjarja.getSource()== mat)
mbushMatricenString(rreshtii,shtylle); //Thirr metoden
if (ngjarja.getSource()== buton1)
mbushVektorinString1( rreshtii,shtylle);
try { Integer.parseInt(teksti1.getText());
Integer.parseInt(teksti2.getText());
} catch (NumberFormatException e) {
JOptionPane.showConfirmDialog(null, "Please enter numbers only", "naughty", JOptionPane.CANCEL_OPTION);
}
}
The problem is ActionListener will only be called when the user "actions" the field (typically by pressing Enter)
You could...
Use a InputVerfier which allows you to verify the state of the field.
Take a look at Validting Input for more details...
You Could...
Use a DocumentFilter to actually prevent the user from entering anything you didn't want them to.
Take a look at Implementing a Document Filter and MDP's Weblog for examples...
You Could...
Use a JSpinner instead
Have a look at this example this only accepts number from user and displayed appropriate error message in JOptionPane.
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
public class Test {
public Test() {
initComponents();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Test();
}
});
}
private void initComponents() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField jtf = new JTextField();
//add filter to document
((AbstractDocument) jtf.getDocument()).setDocumentFilter(new MyDocumentFilter());
frame.add(jtf);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
class MyDocumentFilter extends DocumentFilter {
#Override
public void replace(FilterBypass fb, int i, int i1, String string, AttributeSet as) throws BadLocationException {
for (int n = string.length(); n > 0; n--) {//an inserted string may be more than a single character i.e a copy and paste of 'aaa123d', also we iterate from the back as super.XX implementation will put last insterted string first and so on thus 'aa123d' would be 'daa', but because we iterate from the back its 'aad' like we want
char c = string.charAt(n - 1);//get a single character of the string
System.out.println(c);
if (Character.isDigit(c)) {//if its an alphabetic character or white space
super.replace(fb, i, i1, String.valueOf(c), as);//allow update to take place for the given character
} else {//it was not an alphabetic character or white space
System.out.println("Not allowed");
JOptionPane.showMessageDialog(null, "Only Numbers are allowed");
}
}
}
#Override
public void remove(FilterBypass fb, int i, int i1) throws BadLocationException {
super.remove(fb, i, i1);
}
#Override
public void insertString(FilterBypass fb, int i, String string, AttributeSet as) throws BadLocationException {
super.insertString(fb, i, string, as);
}
}
Use This:
public class CustomTextField extends JTextField implements KeyListener{
public CustomTextField() {
super();
addKeyListener(this);
}
#Override
public void keyPressed(KeyEvent arg0) {
}
#Override
public void keyReleased(KeyEvent arg0) {
}
#Override
public void keyTyped(KeyEvent event) {
char c = event.getKeyChar();
if (!(Character.isDigit(c) || c == KeyEvent.VK_BACK_SPACE || c== KeyEvent.VK_DELETE)) {
event.consume();
}
}
}
Related
How to limit the number of characters entered in a JTextField?
Suppose I want to enter say 5 characters max. After that no characters can be entered into it.
http://www.rgagnon.com/javadetails/java-0198.html
import javax.swing.text.PlainDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
public class JTextFieldLimit extends PlainDocument {
private int limit;
JTextFieldLimit(int limit) {
super();
this.limit = limit;
}
public void insertString( int offset, String str, AttributeSet attr ) throws BadLocationException {
if (str == null) return;
if ((getLength() + str.length()) <= limit) {
super.insertString(offset, str, attr);
}
}
}
Then
import java.awt.*;
import javax.swing.*;
public class DemoJTextFieldWithLimit extends JApplet{
JTextField textfield1;
JLabel label1;
public void init() {
getContentPane().setLayout(new FlowLayout());
//
label1 = new JLabel("max 10 chars");
textfield1 = new JTextField(15);
getContentPane().add(label1);
getContentPane().add(textfield1);
textfield1.setDocument
(new JTextFieldLimit(10));
}
}
(first result from google)
If you wanna have everything into one only piece of code, then you can mix tim's answer with the example's approach found on the API for JTextField, and you'll get something like this:
public class JTextFieldLimit extends JTextField {
private int limit;
public JTextFieldLimit(int limit) {
super();
this.limit = limit;
}
#Override
protected Document createDefaultModel() {
return new LimitDocument();
}
private class LimitDocument extends PlainDocument {
#Override
public void insertString( int offset, String str, AttributeSet attr ) throws BadLocationException {
if (str == null) return;
if ((getLength() + str.length()) <= limit) {
super.insertString(offset, str, attr);
}
}
}
}
Then there is no need to add a Document to the JTextFieldLimit due to JTextFieldLimit already have the functionality inside.
Read the section from the Swing tutorial on Implementing a DocumentFilter for a more current solution.
This solution will work an any Document, not just a PlainDocument.
This is a more current solution than the one accepted.
Great question, and it's odd that the Swing toolkit doesn't include this functionality natively for JTextFields. But, here's a great answer from my Udemy.com course "Learn Java Like a Kid":
txtGuess = new JTextField();
txtGuess.addKeyListener(new KeyAdapter() {
public void keyTyped(KeyEvent e) {
if (txtGuess.getText().length() >= 3 ) // limit textfield to 3 characters
e.consume();
}
});
This limits the number of characters in a guessing game text field to 3 characters, by overriding the keyTyped event and checking to see if the textfield already has 3 characters - if so, you're "consuming" the key event (e) so that it doesn't get processed like normal.
Just Try This :
textfield.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyTyped(java.awt.event.KeyEvent evt) {
if(textfield.getText().length()>=5&&!(evt.getKeyChar()==KeyEvent.VK_DELETE||evt.getKeyChar()==KeyEvent.VK_BACK_SPACE)) {
getToolkit().beep();
evt.consume();
}
}
});
I have solved this problem by using the following code segment:
private void jTextField1KeyTyped(java.awt.event.KeyEvent evt) {
boolean max = jTextField1.getText().length() > 4;
if ( max ){
evt.consume();
}
}
import java.awt.KeyboardFocusManager;
import javax.swing.InputVerifier;
import javax.swing.JTextField;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
/**
*
* #author Igor
*/
public class CustomLengthTextField extends JTextField {
protected boolean upper = false;
protected int maxlength = 0;
public CustomLengthTextField() {
this(-1);
}
public CustomLengthTextField(int length, boolean upper) {
this(length, upper, null);
}
public CustomLengthTextField(int length, InputVerifier inpVer) {
this(length, false, inpVer);
}
/**
*
* #param length - maksimalan length
* #param upper - turn it to upercase
* #param inpVer - InputVerifier
*/
public CustomLengthTextField(int length, boolean upper, InputVerifier inpVer) {
super();
this.maxlength = length;
this.upper = upper;
if (length > 0) {
AbstractDocument doc = (AbstractDocument) getDocument();
doc.setDocumentFilter(new DocumentSizeFilter());
}
setInputVerifier(inpVer);
}
public CustomLengthTextField(int length) {
this(length, false);
}
public void setMaxLength(int length) {
this.maxlength = length;
}
class DocumentSizeFilter extends DocumentFilter {
public void insertString(FilterBypass fb, int offs, String str, AttributeSet a)
throws BadLocationException {
//This rejects the entire insertion if it would make
//the contents too long. Another option would be
//to truncate the inserted string so the contents
//would be exactly maxCharacters in length.
if ((fb.getDocument().getLength() + str.length()) <= maxlength) {
super.insertString(fb, offs, str, a);
}
}
public void replace(FilterBypass fb, int offs,
int length,
String str, AttributeSet a)
throws BadLocationException {
if (upper) {
str = str.toUpperCase();
}
//This rejects the entire replacement if it would make
//the contents too long. Another option would be
//to truncate the replacement string so the contents
//would be exactly maxCharacters in length.
int charLength = fb.getDocument().getLength() + str.length() - length;
if (charLength <= maxlength) {
super.replace(fb, offs, length, str, a);
if (charLength == maxlength) {
focusNextComponent();
}
} else {
focusNextComponent();
}
}
private void focusNextComponent() {
if (CustomLengthTextField.this == KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner()) {
KeyboardFocusManager.getCurrentKeyboardFocusManager().focusNextComponent();
}
}
}
}
Just put this code in KeyTyped event:
if ((jtextField.getText() + evt.getKeyChar()).length() > 20) {
evt.consume();
}
Where "20" is the maximum number of characters that you want.
I use a JTextArea where using double click I can able to select the word at any place but I don't want to enable edit. Which means text can be entered only at the end of text area and not anywhere in between.
I have tried with mouse listeners like below:
#Override
public void mouseClicked(MouseEvent me) {
if(SwingUtilities.isLeftMouseButton(me)){
System.err.println("clicked");
int pos = textArea.getCaretPosition();
if(pos < textArea.getDocument().getLength()){
textArea.setCaretPosition(textArea.getDocument().getLength());
}
}
}
This makes double click not to select the word. I understand it is because caret position is moved to end. But how can I achieve this?
Check out the Protected Text Component which allows you to protect multiple areas of a Document from change.
Or if you don't need to be able to "select" any of the protected text than a simpler solution is to use a NavigationFilter:
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class NavigationFilterPrefixWithBackspace extends NavigationFilter
{
private int prefixLength;
private Action deletePrevious;
public NavigationFilterPrefixWithBackspace(int prefixLength, JTextComponent component)
{
this.prefixLength = prefixLength;
deletePrevious = component.getActionMap().get("delete-previous");
component.getActionMap().put("delete-previous", new BackspaceAction());
component.setCaretPosition(prefixLength);
}
#Override
public void setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
{
fb.setDot(Math.max(dot, prefixLength), bias);
}
#Override
public void moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
{
fb.moveDot(Math.max(dot, prefixLength), bias);
}
class BackspaceAction extends AbstractAction
{
#Override
public void actionPerformed(ActionEvent e)
{
JTextComponent component = (JTextComponent)e.getSource();
if (component.getCaretPosition() > prefixLength)
{
deletePrevious.actionPerformed( null );
}
}
}
private static void createAndShowUI()
{
JTextField textField = new JTextField("Prefix_", 20);
textField.setNavigationFilter( new NavigationFilterPrefixWithBackspace(7, textField) );
JFrame frame = new JFrame("Navigation Filter Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(textField);
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
Okay, this is slightly hacky...
Basically what this does is installs a "protected" DocumentFilter, which will only allow input to put in from a certain point in the Document.
It overrides the JTextArea's insert-break key binding (Enter) and records a marker. The "protected" DocumentFilter then ensures that the content does not precede this point
I was forced to implement a KeyListener on the field to move the cursor to the end of the input, while the DocumentFilter was capable of handling this, it did present some issues with deleting and general usability. This also ensures that the selection is un-highlighted when new content is added...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class Terminal {
public static void main(String[] args) {
new Terminal();
}
public Terminal() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JTextArea terminal = new JTextArea(20, 40);
ProtectedDocumentFilter.install(terminal);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(terminal));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static interface UserInput {
public int getUserInputStart();
public void setUserInputStart(int lastPoint);
}
public static class DefaultUserInput implements UserInput {
private final JTextArea textArea;
private int userInputStart;
public DefaultUserInput(JTextArea ta) {
textArea = ta;
ActionMap am = ta.getActionMap();
Action action = am.get("insert-break");
am.put("insert-break", new ProxyAction(action));
ta.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (textArea.getCaretPosition() != textArea.getDocument().getLength()) {
textArea.setCaretPosition(textArea.getDocument().getLength());
}
}
});
}
#Override
public void setUserInputStart(int userInputStart) {
this.userInputStart = userInputStart;
}
#Override
public int getUserInputStart() {
return userInputStart;
}
public class ProxyAction extends AbstractAction {
private final Action proxy;
public ProxyAction(Action proxy) {
this.proxy = proxy;
}
#Override
public void actionPerformed(ActionEvent e) {
proxy.actionPerformed(e);
int range = textArea.getCaretPosition() - userInputStart;
userInputStart += range;
}
}
}
public static class ProtectedDocumentFilter extends DocumentFilter {
protected static void install(JTextArea textArea) {
UserInput ui = new DefaultUserInput(textArea);
((AbstractDocument) textArea.getDocument()).setDocumentFilter(new ProtectedDocumentFilter(ui));
}
private UserInput userInput;
public ProtectedDocumentFilter(UserInput userInput) {
this.userInput = userInput;
}
public UserInput getUserInput() {
return userInput;
}
#Override
public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException {
if (offset < getUserInput().getUserInputStart()) {
offset = fb.getDocument().getLength();
}
System.out.println("Insert");
super.insertString(fb, offset, string, attr);
}
#Override
public void remove(FilterBypass fb, int offset, int length) throws BadLocationException {
if (offset >= getUserInput().getUserInputStart()) {
super.remove(fb, offset, length);
}
}
#Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
if (offset < getUserInput().getUserInputStart()) {
offset = fb.getDocument().getLength();
length = 0;
}
super.replace(fb, offset, length, text, attrs);
if (text.contains("\n")) {
int lastPoint = offset + text.lastIndexOf("\n");
if (lastPoint > getUserInput().getUserInputStart()) {
getUserInput().setUserInputStart(lastPoint + 1);
}
}
}
}
}
This is just an example, you're going to need to play with it and tweak it to meet your own needs....
I want my program to be able to tell if what is inside my two JTextFields is an integer or a String.
CODE
public void actionPerformed(ActionEvent e){
if(inputH.getText().equals(" Set Height ") ||
inputW.getText().equals(" Set Width ")){
JOptionPane.showMessageDialog(frame,
"Change Height And Width To A Number.",
"Change Height To A Number",
JOptionPane.ERROR_MESSAGE);
}
}
});
This if statement tests if what is in the JTextField is " Set Height " or " Set Width " but i want them to test if what is in them is a number, how would I do that?
i cant figure out the Integer.ParseInt. Please help.
Not sure exactly where in your code the test is being performed, but you can use this method to determine if a String is an integer:
public static boolean isInteger(String s) {
try {
Integer.parseInt(s);
} catch(NumberFormatException e) {
return false;
}
// if exception isn't thrown, then it is an integer
return true;
}
Less expensive none exception based way, assuming your code does not need to throw an exception:
public static boolean isInt(String s){
for(int i = 0; i < s.length(); i++){
if(!Character.isDigit(s.charAt(i))){
return false;
}
}
return true;
}
For restricting a User from entering anything but digits, you can set a DocumentFilter on the JTextField.
Here is a small example :
import java.awt.*;
import javax.swing.*;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
public class InputInteger
{
private JTextField tField;
private MyDocumentFilter documentFilter;
private void displayGUI()
{
JFrame frame = new JFrame("Input Integer Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setBorder(
BorderFactory.createEmptyBorder(5, 5, 5, 5));
tField = new JTextField(10);
((AbstractDocument)tField.getDocument()).setDocumentFilter(
new MyDocumentFilter());
contentPane.add(tField);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args)
{
Runnable runnable = new Runnable()
{
#Override
public void run()
{
new InputInteger().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
class MyDocumentFilter extends DocumentFilter
{
#Override
public void insertString(DocumentFilter.FilterBypass fp
, int offset, String string, AttributeSet aset)
throws BadLocationException
{
int len = string.length();
boolean isValidInteger = true;
for (int i = 0; i < len; i++)
{
if (!Character.isDigit(string.charAt(i)))
{
isValidInteger = false;
break;
}
}
if (isValidInteger)
super.insertString(fp, offset, string, aset);
else
Toolkit.getDefaultToolkit().beep();
}
#Override
public void replace(DocumentFilter.FilterBypass fp, int offset
, int length, String string, AttributeSet aset)
throws BadLocationException
{
int len = string.length();
boolean isValidInteger = true;
for (int i = 0; i < len; i++)
{
if (!Character.isDigit(string.charAt(i)))
{
isValidInteger = false;
break;
}
}
if (isValidInteger)
super.replace(fp, offset, length, string, aset);
else
Toolkit.getDefaultToolkit().beep();
}
}
Or one can simply use this approach, as given by #Carlos Heuberger
#Override
public void insertString(FilterBypass fb, int off
, String str, AttributeSet attr)
throws BadLocationException
{
// remove non-digits
fb.insertString(off, str.replaceAll("\\D++", ""), attr);
}
#Override
public void replace(FilterBypass fb, int off
, int len, String str, AttributeSet attr)
throws BadLocationException
{
// remove non-digits
fb.replace(off, len, str.replaceAll("\\D++", ""), attr);
}
You can process the key event in the action method also. Try this
First make a JTextField
JTextField j=new JTextField();
Then add KeyListner to this JTextField as
j.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
if(arg0.getKeyCode()>57 || arg0.getKeyCode()<48) {
//your error message and other handling code here
JOptionPane.showMessageDialog(PatentFrame, "Only integer allowed", "Message title",JOptionPane.ERROR_MESSAGE);
}
}
#Override
public void keyPressed(KeyEvent arg0) {
// TODO Auto-generated method stub
}
});
48 is ASCII code for 0 and 57 is ASCII code for 9. You can also ignore virtual keys like shift. See ASCII chart
I need to not allow any characters to be entered after X have been typed. I need to send a beep after X characters have been typed. I know how to do this after the user presses enter, but I need to do it before the user presses enter. The approach I found from Oracle's site is to add a DocumentSizeFilter to the JTextPane. I can't get this to notify the user when they have gone over (it doesn't work until they press enter). This is a sample of what I have.
public class EndCycleTextAreaRenderer extends JTextPane
implements TableCellRenderer {
private final int maxNumberOfCharacters = 200;
public EndCycleTextAreaRenderer() {
StyledDocument styledDoc = this.getStyledDocument();
AbstractDocument doc;
doc = (AbstractDocument)styledDoc;
doc.setDocumentFilter(new DocumentSizeFilter(maxNumberOfCharacters ));
}
Override the insertString method of the document in the JTextPane so that it doesn't insert any more characters once the maximum has been reached.
For example:
JTextPane textPane = new JTextPane(new DefaultStyledDocument() {
#Override
public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
if ((getLength() + str.length()) <= maxNumberOfCharacters) {
super.insertString(offs, str, a);
}
else {
Toolkit.getDefaultToolkit().beep();
}
}
});
Update:
You can change your class as follows:
public class EndCycleTextAreaRenderer extends JTextPane implements TableCellRenderer {
private final int maxNumberOfCharacters = 200;
public EndCycleTextAreaRenderer() {
setStyledDocument(new DefaultStyledDocument() {
#Override
public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
if ((getLength() + str.length()) <= maxNumberOfCharacters) {
super.insertString(offs, str, a);
} else {
Toolkit.getDefaultToolkit().beep();
}
}
});
}
}
Here is a sample program, for you where, as you enter the fourth time into the TextPane it will beep, without even you pressing the Enter key:
import javax.swing.*;
import javax.swing.text.*;
import java.awt.Toolkit;
public class TextPaneLimit extends JFrame
{
private JPanel panel;
private JTextPane tpane;
private AbstractDocument abDoc;
public TextPaneLimit()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
panel = new JPanel();
tpane = new JTextPane();
Document doc = tpane.getStyledDocument();
if (doc instanceof AbstractDocument)
{
abDoc = (AbstractDocument)doc;
abDoc.setDocumentFilter(new DocumentSizeFilter(3));
}
panel.add(tpane);
add(panel);
pack();
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new TextPaneLimit().setVisible(true);
}
});
}
}
class DocumentSizeFilter extends DocumentFilter {
private int max_Characters;
private boolean DEBUG;
public DocumentSizeFilter(int max_Chars) {
max_Characters = max_Chars;
DEBUG = false;
}
public void insertString(FilterBypass fb
, int offset
, String str
, AttributeSet a)
throws BadLocationException {
if (DEBUG) {
System.out.println("In DocumentSizeFilter's insertString method");
}
if ((fb.getDocument().getLength() + str.length()) <= max_Characters)
super.insertString(fb, offset, str, a);
else
Toolkit.getDefaultToolkit().beep();
}
public void replace(FilterBypass fb
, int offset, int length
, String str, AttributeSet a)
throws BadLocationException {
if (DEBUG) {
System.out.println("In DocumentSizeFilter's replace method");
}
if ((fb.getDocument().getLength() + str.length()
- length) <= max_Characters)
super.replace(fb, offset, length, str, a);
else
Toolkit.getDefaultToolkit().beep();
}
}
Hope this might help.
I would suggest checking the # of characters with every key entered by adding a keyReleasedListener, it is something I used in a recent GUI of mine to check bounds seemingly instantly and display errors to the user as they typed.
Here is how I implemented it on one of my TextFields:
carbonTextField.addKeyListener(new java.awt.event.KeyAdapter()
{
public void keyReleased(java.awt.event.KeyEvent evt)
{
carbonTextFieldKeyReleased(evt);
}
});
Check the following code:
txtpnDesc.addKeyListener(new KeyAdapter() {
#Override
public void keyTyped(KeyEvent e) {
if(txtpnDesc.getText().length() == 30)
{
e.consume();
}
}
});
I'm somewhat used to the GUI idiom where when I type something wrong in a text input field a balloon pops up from the field with info about what I got wrong / expected input. It remains visible until I type again.
But now I couldn't find any example to point to.
Given a JTextfield do you know of any library/code that would display such a balloon when triggered by my keylistener?
#see http://www.javapractices.com/topic/TopicAction.do?Id=151
Balloon Tip is a library that does that:
balloonTip = new BalloonTip(f, "Tooltip msg");
That was all needed! If you insist on a having it be a tooltip too:
tooltipBalloon = new BalloonTip(someComponent, "I'm a balloon tooltip!");
// Now convert this balloon tip to a tooltip, such that the tooltip shows up after 500 milliseconds and stays visible for 3000 milliseconds
ToolTipUtils.balloonToToolTip(tooltipBalloon, 500, 3000);
The link given by James Poulson probably provides a better solution, but I had to see if this were possible with some simple Java code using a DocumentFilter and a JWindow. Here's one possible way to do this:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.Window;
import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.PlainDocument;
public class InfoBalloon extends JPanel {
private static final int PREF_WIDTH = 400;
private static final int PREF_HEIGHT = 300;
private static final String REGEX_TEST = "\\d*";
private static final String ERROR_TEXT = "Please only add numbers to the text field";
private JTextField textField = new JTextField(10);
private JWindow errorWindow;
public InfoBalloon() {
add(new JLabel("Please Enter Number"));
add(textField);
((PlainDocument)textField.getDocument()).setDocumentFilter(new MyNumberDocFilter());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_WIDTH, PREF_HEIGHT);
}
private void showErrorWin() {
if (errorWindow == null) {
JLabel errorLabel = new JLabel(ERROR_TEXT);
Window topLevelWin = SwingUtilities.getWindowAncestor(this);
errorWindow = new JWindow(topLevelWin);
JPanel contentPane = (JPanel) errorWindow.getContentPane();
contentPane.add(errorLabel);
contentPane.setBackground(Color.white);
contentPane.setBorder(BorderFactory.createLineBorder(Color.LIGHT_GRAY));
errorWindow.pack();
}
Point loc = textField.getLocationOnScreen();
errorWindow.setLocation(loc.x + 20, loc.y + 30);
errorWindow.setVisible(true);
}
private boolean textOK(String text) {
if (text.matches(REGEX_TEST)) {
return true;
}
return false;
}
private class MyNumberDocFilter extends DocumentFilter {
#Override
public void insertString(FilterBypass fb, int offset, String string,
AttributeSet attr) throws BadLocationException {
if (textOK(string)) {
super.insertString(fb, offset, string, attr);
if (errorWindow != null && errorWindow.isVisible()) {
errorWindow.setVisible(false);
}
} else {
showErrorWin();
}
}
#Override
public void replace(FilterBypass fb, int offset, int length, String text,
AttributeSet attrs) throws BadLocationException {
if (textOK(text)) {
super.replace(fb, offset, length, text, attrs);
if (errorWindow != null && errorWindow.isVisible()) {
errorWindow.setVisible(false);
}
} else {
showErrorWin();
}
}
#Override
public void remove(FilterBypass fb, int offset, int length)
throws BadLocationException {
super.remove(fb, offset, length);
if (errorWindow != null && errorWindow.isVisible()) {
errorWindow.setVisible(false);
}
}
}
private static void createAndShowUI() {
JFrame frame = new JFrame("Info Balloon");
frame.getContentPane().add(new InfoBalloon());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
Constructive or destructive criticism is most welcome!