How to Create Warning, Information, and Error Dialogs in Swing?

How can I create a warning, information, or error dialog in Swing with a standard 'Ok' button and a red cross icon?

import javax.swing.*;

public class DialogExample {
    public static void main(String[] args) {
        // Example for showing an error dialog
        SwingUtilities.invokeLater(() -> {
            UIManager.put("OptionPane.okButtonText", "OK");
            JOptionPane.showMessageDialog(null, 
                "This is an error message.", 
                "Error", 
                JOptionPane.ERROR_MESSAGE);
        });
    }
}

Creating dialogs in Java Swing is essential for displaying important information, alerts, or errors to users. Swing provides a straightforward way to open standard dialogs with different message types, such as warning, information, and error messages.

import javax.swing.*;

public class SwingDialogs {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            // Information dialog
            JOptionPane.showMessageDialog(null, "This is an information message.", "Information", JOptionPane.INFORMATION_MESSAGE);
            
            // Warning dialog
            JOptionPane.showMessageDialog(null, "This is a warning message.", "Warning", JOptionPane.WARNING_MESSAGE);
            
            // Error dialog
            JOptionPane.showMessageDialog(null, "This is an error message.", "Error", JOptionPane.ERROR_MESSAGE);
        });
    }
}

Causes

• Improper initialization of dialog components
• Incorrect icon setup
• Wrong dialog type passed to JOptionPane

Solutions

• Utilize JOptionPane's static methods to create dialogs easily
• Ensure that the icon parameter is correctly specified for different dialog types
• Wrap dialog creation code in Event Dispatch Thread (EDT) to ensure thread safety

Mistake: Not using the Event Dispatch Thread to show dialogs.

Solution: Always wrap your dialog code in SwingUtilities.invokeLater or SwingWorker to ensure that it runs on the EDT.

Mistake: Failing to customize dialog texts to match application style.

Solution: Set the dialog text and button labels to be consistent across your application for a cohesive user experience.