Android: Cast View To View

I have a class that extends View (MyView extends View) In Activity I have next: View view = (View)findViewById(R.id.relative_layout_view); //here I have error because of c

Solution 1:

MyView is a View, but View is not necessarily a MyView, so you need to explicitly cast it.

If it crashes, it means that the view with the ID relative_layout_view is NOT of type MyView, you need to make sure what its type is in the layout XML.

Solution 2:

Use this way Just add in xml like

<YourPackage Name.MyView
android:layout_height="wrap_content"android:layout_width="wrap_content"android:id="@+id/myview"android:layout_gravity="center"
>   
</YourPackage Name.MyView>

and after that use in activity as given below

MyViewview= (MyView)findViewById(R.id.relative_layout_view);

Solution 3:

Why not just do

MyViewview= (MyView) findViewById(R.id.relative_layout_view);

Solution 4:

simple answer is that you are down casting your view instance to MyView.

its not always safe to down cast any object to its subclass and that is why compiler forces programmer to explicitly typecast his object to subclass.

In your case, view is not of type MyView. and this is the reason compiler gives classCastException.

But if R.id.relative_layout_view was of type MyWiew, it would have not generated any exception.