LibGDX - 在此阶段为舞台和演员获取事件

Question

我在舞台上添加了一些演员。当我尝试处理Actors tap事件时，pan功能无法正常工作。为什么？怎么做才有效？ 这是我的问题的摘要。

Main.java

public class Main extends ApplicationAdapter  implements GestureListener{

    static Grid grid;
    static Stage main_stage;
    static InputMultiplexer inputs;
    static GestureDetector gdect;

    @Override
    public void create () {
        main_stage = new Stage();
        inputs = new InputMultiplexer();
        grid = new Grid();
        grid.addToStage(main_stage);
        inputs.addProcessor(main_stage);
        dect = new GestureDetector(this);
        inputs.addProcessor(gdect);
        Gdx.input.setInputProcessor(inputs);
    }

    @Override
    public boolean pan(float x, float y, float deltaX, float deltaY) {
        System.out.println("pan");
        return false;
    }
}

Grid.java

public class Grid {

    static Fields [] fields;

    void addToStage(Stage stage){
    for(int i = 0; i < fields.length; i++)
        stage.addActor(fields[i]);
    }
}

Fields.java

public class Fields extends Actor {

    addListener(new ActorGestureListener(){
        public void tap(InputEvent event, float x, float y, int count, int button) {
            System.out.println("tap");
        }
    });
}