Validate a value on the lostFocus event : TextField « Swing JFC « Java

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Java » Swing JFC » TextField Screenshots  Validate a value on the lostFocus event      import java.awt.event.FocusEvent; import java.awt.event.FocusListener; import javax.swing.JComponent; import javax.swing.JTextField; import javax.swing.SwingUtilities; public class Main {   JTextField tf1;   public void init() {     tf1 = new JTextField(5);       tf1.addFocusListener(new FocusListener() {       public void focusGained(FocusEvent e) {       };       public void focusLost(FocusEvent e) {         if (!e.isTemporary()) {           String content = tf1.getText();           if (!content.equals("a") ) {             System.out.println("illegal value! " + content);             SwingUtilities.invokeLater(new FocusGrabber(tf1));           }         }       }     });   } } class FocusGrabber implements Runnable {   private JComponent component;   public FocusGrabber(JComponent component) {     this.component = component;   }   public void run() {     component.grabFocus();   } }                       Related examples in the same category 1.  Make a Text Field two columns wide 2.  Water mark text field 3.  Auto complete TextField 4.  Text fields and Java events 5.  JTextField Alignment Sample 6.  Create the textfield 7.  FieldEdit - an Applet to validate data as it's being entered 8.  TextField with only Integer value 9.  File Name Bean 10.  Textfield only accepts numbers 11.  Overwritable TextField 12.  Numeric TextField 13.  Passive TextField 1 14.  Passive TextField 2 15.  Text Accelerator Example 16.  TextField Look Ahead Example 17.  Passive TextField 3 18.  Non Wrapping(Wrap) TextPane 19.  EditabilityExample 20.  Bounded TextField 21.  TextField Elements 22.  TextFieldViews 2 23.  TextField with Constaints 24.  JTextField Sample 2 25.  JTextField Verifier Sample 26.  A simple label for field form panel 27.  A hack to make a JTextField really 2 columns wide 28.  Limit JTextField input to a maximum length 29.  Make sure that my JTextField has the focus when a JFrame is created 30.  Make the ENTER key act like the TAB key 31.  Setting up a textfield and modifying its horizontal alignment at runtime 32.  Aligning the Text in a JTextField Component 33.  Based on JTextField content, enable or disable a JButton 34.  Cut, paste, and copy in a JTextField under program control. 35.  Add key listener event handler to JTextField 36.  Right justified JTextfield content 37.  Set the focus on a particular JTextField 38.  Associate JLabel component with a JTextField 39.  Right justified JTextField contents 40.  Modify horizontal alignment of text field at runtime 41.  Make sure that my Text field has the focus when a JFrame is created 42.  Firing Item Events 43.  extends JTextField to create integer JTextField 44.  JTextField Max Length