如何将任何 android 元素传递给非 activity class 并在 class 中为该元素设置 onTouch？

Question

我需要将 UI 元素引用传递给非 activity class，无论该元素是什么类型。然后将 onTouchEvent 附加到非 activity class 内的那个元素。

我该怎么做？我在网上搜索过，但没有找到任何有用的信息。

Answer 1

您通过构造函数或方法调用传递上下文。示例：

MyNonActivityClass myObject = new MyNonActivityClass(getActivity());

MyNonActivityClass

import android.content.Context;
import your.package.name.R; // notice the R you should add your package
                            // infront of R it should be something like 
                            // com.example.myapp.R
public class MyNonActivityClass{
    private Context context;
    public MyNonActivityClass(Context c){
        if(context instanceof MyActivityClass){
            this.context=c;
        }
        /** you can do multi if else statements for multi activity classes **/
    }
    private void someMethodToHandleUi(){
        View v = ((MyActivityClass)context).findViewById(R.id.myView);
        v.setOnTouchListener(new OnTouchListener(){
            // rest of your code
        });
    }
}

Answer 2

我找到了不需要上下文或 if 条件的解决方案，我需要做的就是将元素引用作为对象传递给 class，而不是使用 WeakReference 传递对视图的引用。

代码如下：

public class NonActivityClass{
   private WeakReference<Object> target;

   public NonActivityClass(Object target){
      this.target = new WeakReference<Object>(target);
   }

   @Nullable
   public Object getTarget() {
      return target == null ? null : target.get();
   }

   public void doSomethingWithUIElement(){
      View view = (View) getTarget();

      view.setOnTouchListener(new View.OnTouchListener() {       
         @Override
         public boolean onTouch(View v, MotionEvent event) {

            return true;
         }
      });
   }
}

如何将任何 android 元素传递给非 activity class 并在 class 中为该元素设置 onTouch？

How to pass any android element to non-activity class and set onTouch for that element in that class?

android

element

class

touch-event

android-activity

MyNonActivityClass