The symptom of the problem revolves around this process.
textMobNo
gains focus...- which causes
textRegNo
to lose focus... textRegNo
is validated and found to be invalid,textRegNo
now displays an error message...- Focus is transferred to the dialog and...
textMobNo
loses focus (because the dialog gained focus)
You should avoid using focus as a means to validate fields if you can and instead use an InputVerifier
Simple example
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.JTextComponent;
public class TestInputVerifier {
public static void main(String[] args) {
new TestInputVerifier();
}
public TestInputVerifier() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
JTextField field = new JTextField(20);
field.setInputVerifier(new RegExpInputVerifier("^[A-Z]{2}[ -][0-9]{1,2}(?: [A-Z])?(?: [A-Z]*)? [0-9]{4}$"));
add(field, gbc);
field = new JTextField(20);
field.setInputVerifier(new RegExpInputVerifier("^[789]\\d{9}$"));
add(field, gbc);
}
}
public class RegExpInputVerifier extends InputVerifier {
private String expression;
public RegExpInputVerifier(String expression) {
this.expression = expression;
}
public String getExpression() {
return expression;
}
@Override
public boolean verify(JComponent input) {
boolean verified = false;
if (input instanceof JTextComponent) {
JTextComponent field = (JTextComponent) input;
String regNo1 = field.getText();
Pattern pattern1 = Pattern.compile(expression);
Matcher matcher1 = pattern1.matcher(regNo1);
}
return verified;
}
}
}