A utility class that quickly loads FXML files.

FXMLQuickLoader.java

package me.jacoblockard.blogger.util;

import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;

import java.io.IOException;
import java.net.URL;

/**
 * Contains methods for conveniently loading FXML files. Note that this class is designed for very specific use cases;
 * for any kind of complex FXML loading functionality, the JavaFX FXMLLoader should be used instead.
 *
 * @version 0.1.1
 * @author Jacob Lockard
 */
public class FXMLQuickLoader {
    /**
     * Loads the FXML file at the given location, potentially with the given controller, controller factory, and root.
     *
     * @param location A URL object representing the location of the FXML file.
     * @param controller An Object representing the controller to associate with the loaded file, or null if no
     *                   controller is desired.
     * @param root An Object representing the root to associate with the loaded file, or null if no root is desired.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(URL location, Object controller, Object root) throws IOException {
        FXMLLoader loader;

        // Initialize the FXMLLoader.
        loader = new FXMLLoader();
        // Set its location.
        loader.setLocation(location);
        // Check if the controller exists.
        if (controller != null) {
            // If it does, set the loader's controller.
            loader.setController(controller);
        }
        // Check if the root exists.
        if (root != null) {
            // If it does, set the loader's root.
            loader.setRoot(root);
        }

        // Load the FXML file.
        return loader.load();
    }

    /**
     * Loads the FXML file at the given file path, potentially with the given controller, controller factory, and root.
     *
     * @param locationPath A String object representing the file path to the FXML file.
     * @param controller An Object representing the controller to associate with the loaded file, or null if no
     *                   controller is desired.
     * @param root An Object representing the root to associate with the loaded file, or null if no root is desired.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(String locationPath, Object controller, Object root) throws IOException {
        return load(FXMLQuickLoader.class.getResource(locationPath), controller, root);
    }

    /**
     * Loads the FXML file at the given location, potentially with the given controller.
     *
     * @param location A URL object representing the location of the FXML file.
     * @param controller An Object representing the controller to associate with the loaded file, or null if no
     *                   controller is desired.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(URL location, Object controller) throws IOException {
        return load(location, controller, null);
    }

    /**
     * Loads the FXML file at the given file path, potentially with the given controller.
     *
     * @param locationPath A String object representing the file path to the FXML file.
     * @param controller An Object representing the controller to associate with the loaded file, or null if no
     *                   controller is desired.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(String locationPath, Object controller) throws IOException {
        return load(FXMLQuickLoader.class.getResource(locationPath), controller);
    }

    /**
     * Loads the FXML file at the given location with no controller.
     *
     * @param location A URL object representing the location of the FXML file.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(URL location) throws IOException {
        return load(location, null);
    }

    /**
     * Loads the FXML file at the given file path with no controller.
     *
     * @param locationPath A String object representing the file path to the FXML file.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent load(String locationPath) throws IOException {
        return load(locationPath, new Object());
    }

    /**
     * Loads the FXML file at the given location into the given control.
     *
     * @param control A Parent object representing the control to load the FXML file into.
     * @param location A URL object representing the location of the FXML file.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent loadToControl(Parent control, URL location) throws IOException {
        return load(location, control, control);
    }

    /**
     * Loads the FXML file at the given file path into the given control.
     *
     * @param control A Parent object representing the control to load the FXML file into.
     * @param locationPath A String object representing the file path to the FXML file.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent loadToControl(Parent control, String locationPath) throws IOException {
        return loadToControl(control, FXMLQuickLoader.class.getResource(locationPath));
    }

    /**
     * Loads the FXML file at the default file path into the given control. This method assumes that the FXML file has
     * a name equal to the simple name of the control's class, is a resource, and is contained in a directory called
     * "fxml".
     *
     * @param control An Object that extends Parent representing the control to load the FXML file into.
     * @return a Parent object representing the result of loading the FXML file.
     */
    public static Parent loadToControl(Parent control) throws IOException {
        return loadToControl(control, "/fxml/" + fxmlName(control.getClass()) + ".fxml");
    }

    /**
     * Gets the name of an FXML file for the given class.
     *
     * @param type The class to create an FXML name for.
     * @return a String object representing the name of the FXML file.
     */
    private static String fxmlName(Class type) {
        return type.getSimpleName()
                   .replaceAll("([A-Z]+)([A-Z][a-z])", "$1_$2")
                   .replaceAll("([a-z])([A-Z])", "$1_$2")
                   .toLowerCase();
    }
}