Disable button if JTextFields are empty and RadioButtons are not checked

Question

I have a JDialog with two JTextFields, one ButtonGroup with two RadioButtons and an OK-Button. The button has to be disabled until the TextFields are filled and at least one of the RadioButtons clicked. I'm not sure how to do this.

It works for with the JTextFields using this code:

public class Test {
  public static void main(String... args) {
    ButtonTest.show();
  }

}

class ButtonTest {

  private ButtonTest() {
    JFrame frame = new JFrame("Button Test");
    frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    frame.setLocationByPlatform(true);

    JPanel mainPanel = new JPanel(new GridLayout(4, 1));

    JTextField field1 = new JTextField(20);
    JTextField field2 = new JTextField(20);
    JLabel text = new JLabel();
    JButton printButton = new JButton("Print");
    printButton.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        text.setText(field1.getText() + " - " + field2.getText());
      }
    });
    printButton.setEnabled(!field1.getText().isEmpty() && !field2.getText().isEmpty());
    for (JComponent c : Arrays.asList(field1, field2, text, printButton)) {
      mainPanel.add(c);
    }

    setDocumentListener(field1, field2, printButton);
    setDocumentListener(field2, field1, printButton);

    frame.add(mainPanel);
    frame.pack();
    frame.setVisible(true);
  }

  private void setDocumentListener(JTextField field, JTextField other, JButton button) {
    field.getDocument().addDocumentListener(new DocumentListener() {
      @Override
      public void removeUpdate(DocumentEvent e) {
        changed();
      }

      @Override
      public void insertUpdate(DocumentEvent e) {
        changed();
      }

      @Override
      public void changedUpdate(DocumentEvent e) {
        changed();
      }

      private void changed() {
        setButtonStatus(button, field.getText(), other.getText());
      }
    });
  }

  private void setButtonStatus(JButton button, String field1, String field2) {
    button.setEnabled(!field1.isEmpty() && !field2.isEmpty());
  }

  public static void show() {
    SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        new ButtonTest();
      }
    });
  }
}

But what about the RadioButtons? I guess I have to somehow implement an ItemListener?

Greetings

Answer 1

Check out: Validation of text fields and contact no text field

It provides a general solution for enabling a button when data is entered in all text fields.

You can enhance that solution to also support radio buttons.

But what about the RadioButtons? I guess I have to somehow implement an ItemListener?

You can modify the DataEntered class found in the link above to do the following:

1. implement an ItemListener to simply invoke the isDataEntered() method.
2. create a new addButtonGroup(...) method. This method would save the ButtonGroup and then iterate through all the radio buttons in the group to add the ItemListener to the radio button.
3. then you would need to modify the isDataEntered() method to iterate through each ButtonGroup and invoke the getSelection() method on the ButtonGroup. If the value is null that means no radio button has been selected and you just return false.

Answer 2

You need two tests:

1. Does the JTextField contain non-whitespace text, tested like so, !textField.getText().trim().isEmpty(), and
2. Is one JRadioButton selected, which can be tested by seeing if the ButtonGroup contains a non-null ButtonModel selection via buttonGroup.getSelection() != null

Combined, it could look something like:

private void testToActivateButton() {
    boolean value = !textField.getText().trim().isEmpty() && buttonGroup.getSelection() != null;
    submitButton.setEnabled(value);
}

Then simply call the above method in ActionListeners added to the JRadioButtons and your JTextField's DocumentListener. For example:

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

public class ActivateButton extends JPanel {
    private static final String[] RADIO_TEXTS = {"Hello", "Goodbye"};
    private ButtonGroup buttonGroup = new ButtonGroup();
    private JTextField textField = new JTextField(10);
    private JButton submitButton = new JButton("Submit");

    public ActivateButton() {
        textField.getDocument().addDocumentListener(new DocumentListener() {

            @Override
            public void removeUpdate(DocumentEvent e) {
                testToActivateButton();
            }

            @Override
            public void insertUpdate(DocumentEvent e) {
                testToActivateButton();
            }

            @Override
            public void changedUpdate(DocumentEvent e) {
                testToActivateButton();
            }
        });

        for (String radioText : RADIO_TEXTS) {
            JRadioButton radioButton = new JRadioButton(radioText);
            radioButton.addActionListener(e -> testToActivateButton());
            buttonGroup.add(radioButton);
            add(radioButton);
        }

        submitButton.setEnabled(false);

        add(textField);
        add(submitButton);

    }

    private void testToActivateButton() {
        boolean value = !textField.getText().trim().isEmpty() && buttonGroup.getSelection() != null;
        submitButton.setEnabled(value);
    }

    private static void createAndShowGui() {
        ActivateButton mainPanel = new ActivateButton();

        JFrame frame = new JFrame("ActivateButton");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

Answer 3

You can use isSelected() to check whether the radio button is selected.

Eg:

printButton.setEnabled(!field1.getText().isEmpty() && !field2.getText().isEmpty() && (radioBtn1.isSelected() || radioBtn2.isSelected()) );