从“自定义”视图调用活动方法

Question

How to call an activity method from custom view?

public class CustomView extends LinearLayout {

    private Context mContext;

    public CustomView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attributes) {
        findViewById(R.id.textView).setOnClickListener(v -> ((MyActivity) mContext).onClick(v));
    }
}

This works fine as I know that View is generated from MyActivity .

Is there any way to know which activity has created this CustomView ? Something like getActivity().onClick(v)

Answer 1

Do what all existing widgets do: accept a callback. So:

Step #1: Define some sort of callback or listener interface.

Step #2: Add set...() on the widget to accept an instance of that interface, holding onto it in a field

Step #3: Have the activity, fragment, or whatever call that set...() method

Step #4: Have the view call the callback (if one was supplied) when the event occurs

You can see this pattern implemented for things like setOnClickListener() .