How is JSpinner different than other swing components?

Question

I have a method that can recursively enable/disable all components within a JPanel. There are also exception lists. So I can do the following

• Disable all components in panel1 except for textfield1, textfield3 who should be enabled.
• Enable all components in panel2 except for button2, label3 who should be disabled.

Here is a SSCCE that does exactly that:

import java.awt.Component;
import java.awt.Container;
import java.awt.GridLayout;
import java.util.HashSet;
import java.util.Set;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.SpinnerNumberModel;

public class Main {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        final JPanel panel = new JPanel(new GridLayout(3, 3));

        final JTextField textfield = new JTextField("asdf");
        final JButton button = new JButton("asdf");
        final JCheckBox checkbox = new JCheckBox("asdf");
        final JSpinner spinner = new JSpinner(new SpinnerNumberModel(1, 1, 100, 1));
        final JLabel label = new JLabel("asdf");

        panel.add(textfield);
        panel.add(button);
        panel.add(checkbox);
        panel.add(spinner);
        panel.add(label);
        // fill in some random stuff
        for (int i = 0; i < 4; i++)
            panel.add(new JLabel("asdf"));

        frame.setContentPane(panel);
        frame.setSize(300, 100);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        new Thread(new Runnable() {
            @Override
            public void run() {
                boolean toggle = true;
                while (true) {
                    toggle = !toggle;
                    Set<Component> enableList = new HashSet<Component>();
                    Set<Component> disableList = new HashSet<Component>();
                    enableList.add(textfield);
                    enableList.add(spinner);
                    disableList.add(checkbox);
                    setEnableAllRec(panel, toggle, disableList, enableList);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {}
                }
            }
        }).start();
        frame.setVisible(true);
    }

    public static void setEnableAllRec(Container root, boolean defaultState, Set<Component> disableList, Set<Component> enableList) {
        if (root == null) return;
        for (Component c : root.getComponents()) {
            if (disableList != null && disableList.contains(c)) {
                c.setEnabled(false);
                disableList.remove(c);
            } else if (enableList != null && enableList.contains(c)) {
                c.setEnabled(true);
                enableList.remove(c);
            } else c.setEnabled(defaultState);
            if (c instanceof Container) setEnableAllRec((Container) c, defaultState, disableList, enableList);
        }
    }
}

The SSCCE sets all components every second to enable/disable alternatingly. Except for some components that should always be enabled and some that should always be disabled. That works extremely well except for the JSpinner. It gets detected as a component but can not be found in the list (and therefore is not handled as a special case). All other swing components that I have tried are working as expected.

Can you tell me whats wrong with JSpinner?

I hope the SSCCE is not too confusing... ;)

Answer 1

Simply because a JSpinner contains other components such as 2 buttons and an editor (see the code of javax.swing.plaf.basic.BasicSpinnerUI) and you go recursively on all containers, thus, also on contained components of the JSpinner.

Btw, your Thread is violating the Swing-EDT. You should rather perform that in a Swing Timer

The solution is easy:

import java.awt.Component;
import java.awt.Container;
import java.awt.GridLayout;
import java.util.HashSet;
import java.util.Set;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.SpinnerNumberModel;

public class Main {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        final JPanel panel = new JPanel(new GridLayout(3, 3));

        final JTextField textfield = new JTextField("asdf");
        final JButton button = new JButton("asdf");
        final JCheckBox checkbox = new JCheckBox("asdf");
        final JSpinner spinner = new JSpinner(new SpinnerNumberModel(1, 1, 100, 1));
        final JLabel label = new JLabel("asdf");

        panel.add(textfield);
        panel.add(button);
        panel.add(checkbox);
        panel.add(spinner);
        panel.add(label);
        // fill in some random stuff
        for (int i = 0; i < 4; i++) {
            panel.add(new JLabel("asdf"));
        }

        frame.setContentPane(panel);
        frame.setSize(300, 100);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        new Thread(new Runnable() {
            @Override
            public void run() {
                boolean toggle = true;
                while (true) {
                    toggle = !toggle;
                    Set<Component> enableList = new HashSet<Component>();
                    Set<Component> disableList = new HashSet<Component>();
                    enableList.add(textfield);
                    enableList.add(spinner);
                    disableList.add(checkbox);
                    setEnableAllRec(panel, toggle, disableList, enableList);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                    }
                }
            }
        }).start();
        frame.setVisible(true);
    }

    public static void setEnableAllRec(Container root, boolean defaultState, Set<Component> disableList, Set<Component> enableList) {
        if (root == null) {
            return;
        }
        for (Component c : root.getComponents()) {
            if (disableList != null && disableList.contains(c)) {
                c.setEnabled(false);
                disableList.remove(c);
            } else if (enableList != null && enableList.contains(c)) {
                c.setEnabled(true);
                enableList.remove(c);
            } else {
                c.setEnabled(defaultState);
                if (c instanceof Container) {
                    setEnableAllRec((Container) c, defaultState, disableList, enableList);
                }
            }
        }
    }
}