从自定义对话框 Class 更改 Main UI

Question

我有 2 个 class、Main 和 DialogOrder

主要

public class Main extends Fragment{
ImageView order;


@Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {

     order.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

               new DialogOrder(getActivity()).show();
            }
        });

  return view;
  }
  public void init(Bundle savedInstanceState) {   
   order = (ImageView) view.findViewById(R.id.order);
   order.setImageResource(R.drawable.orderd);
   RelativeLayout.LayoutParams orderparams = new RelativeLayout.LayoutParams(Main.screenHeight / 8, Main.screenHeight / 8);
   orderparams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
   orderparams.addRule(RelativeLayout.CENTER_HORIZONTAL);
    orderparams.setMargins(Main.screenHeight / 80, Main.screenHeight / 80, Main.screenHeight / 80, Main.screenHeight / 30);

    order.setLayoutParams(orderparams);


 }

  public void update_UI(){

    order.setVisibility(View.INVISIBLE);

}

}

对话框顺序

public class DialogOrder extends Dialog {
Button button;
Main main;
Activity context;


public DialogOrder(Activity context) {
    super(context);

    this.context = context;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
 setContentView(R.layout.order_dialog);
 main = new Main();
 button = (Button)findviewbyid(R.id.bd);

 button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

           main.update_UI();
           dismiss();
        }
    });
}}

我想要的是当用户按下对话框中的按钮时设置订单图像不可见现在代码给我 java.lang.NullPointerException

可能我尝试更新 UI 错误所以请有人告诉我从 child class 更新 parent UI class 的正确方法是什么？

Answer 1

您可以通过将主片段传递给对话框构造函数来更新主片段，或者您可以使用 Listener/Callback 在主片段和对话框之间进行通信。

最佳做法是使用 Listener/Callback，因为对话不应访问调用者。这也是将 Dialog 与 Main 片段分离。

首先，通过对话框中的接口创建监听器：

public class DialogOrder extends Dialog {
  ...
  Activity context;
  private DialogListener listener;

  public interface DialogListener {
    void onButtonClicked();
  }

  public DialogOrder(Activity context, DialogListener listener) {
    super(context);
    this.context = context;
    this.listener = listener;
  }

  ...

}

然后，当按钮点击时调用监听器：

public class DialogOrder extends Dialog {

  Activity context;
  private DialogListener listener;

  public interface DialogListener {
    void onButtonClicked();
  }

  public DialogOrder(Activity context, DialogListener listener) {
    super(context);
    this.context = context;
    this.listener = listener;
  }

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    ...

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
           listener.onButtonClicked();
           dismiss();
        }
    });
  }
}

现在，您可以创建与侦听器的对话。像这样：

DialogOrder.DialogListener listener = new DialogOrder.DialogListener() {
   @Ovveride
   public void onButtonClicked() {
     update_UI();
   }
};

DialogOrder dialogOrder = new DialogOrder(getActivity(), listener);
dialogOder.show();

主片段将侦听对话框中单击的按钮。

从自定义对话框 Class 更改 Main UI

change Main UI from custom Dialog Class

java

android

customdialog