如何在Android Studio中使用扩展类的构造函数和方法'getDeclaredConstructor'实例化具有类类型的类

Question

public class MainMenu extends GameMenu{

Table table;

Skin skin;

public MainMenu(){super();};

protected void loadWidgets(){

    skin.add("playButton", com.mygdx.game.LIBGDXwrapper.gameGUI.widgets.MainMenuWidgets.loadPlayButton(table));
    table.row();
    skin.add("hightScoreButton", com.mygdx.game.LIBGDXwrapper.gameGUI.widgets.MainMenuWidgets.loadHighScoreButton(table));
    //table.row();
}

protected void loadInputlisteners(){
    skin.get("playButton", Button.class);

}

@Override
public String toString(){
    return "Menu";
}
}





public abstract class GameMenu extends Stage{

private Settings gameSettings;

//public GameMenu(Settings gameSettings){
 //   this.gameSettings = gameSettings;
//}

public GameMenu(){};

protected abstract void loadWidgets();

protected abstract void loadInputlisteners();

}



private static enum GameMenus {MainMenu(MainMenu.class);
    private final Class<? extends GameMenu> menuType;

    GameMenus(Class<? extends GameMenu> menuType){
        this.menuType = menuType;
    }

    public Class<? extends GameMenu> createInstance(Settings gameSettings){
        GameMenu gui = menuType.getDeclaredConstructor().newInstance();
    }
};

I have been trying to make this work for hours now, is it possible to get an instance of a derived class from 'GameMenu' with the class type 'Class< ? extends GameMenu>'? Note that all derived classes of 'GameMenu' have a constructor that with one argument 'Settings'.

I'm getting NoSuchMethodExpection from the method 'getDeclaredConstructor'.

I would be very grateful if anyone could help me.

Answer 1

So you said:

Note that all derived classes of 'GameMenu' have a constructor that with one argument 'Settings'.

But you use:

menuType.getDeclaredConstructor()

If you take a look at the javadoc , you will see that getDeclaredConstructor() returns the "no args" constructor if any. You probably want to specify the constructor argument type:

menuType.getDeclaredConstructor(Settings.class)