SwingFocusHelper.java

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.JTextComponent;
import java.awt.*;
import java.awt.event.*;
import java.util.function.Consumer;

public class SwingFocusHelper {

    /**
     * Calls JComponent.requestFocusInWindow(), but uses console logging for the result,
     * and logs component diagostics if it fails.
     * @see JComponent#requestFocusInWindow()
     */
    public static boolean requestFocusInWindow(JComponent component, String name) {
        var result = component.requestFocusInWindow();
        SenseiInternalMode.ifInternalMode(() -> {
            printf("requestFocusInWindow for %s returned %s\n", name, result);
            if (!result) {
                printf("  The following may explain why:\n" +
                    "  The component must be displayable, focusable, visible and all of its\n" +
                    "  ancestors (with the exception of the top-level Window) must be visible for the\n" +
                    "  [requestFocusInWindow] request to be granted.\n");
                logComponentFocusState(component, name);
            }
        });
        return result;
    }

    private static void logComponentFocusState(JComponent c, String name) {
        printf("    - component %s isDisplayable:%s isFocusable:%s isVisible:%s\n",
            name, c.isDisplayable(), c.isFocusable(), c.isVisible());
        logComponentFamilyVisibility(c.getParent());
    }

    private static void logComponentFamilyVisibility(@Nullable Container c) {
        if (c != null) {
            printf("    - parent of type %s isVisible:%s\n",
                c.getClass().getName(), c.isVisible());
            logComponentFamilyVisibility(c.getParent());
        }
    }

    private static void printf(String format, Object... params) {
        System.err.printf(format, params);
    }

}