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Editorial Team
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Asked: 2026-05-27T02:10:36+00:00

When declaring custom view in xml, what is the difference between declaring a View

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When declaring custom view in xml, what is the difference between declaring a View of a custom class, or declaring a completely custom view:

<LinearLayout>
<view class="packageName.MyView" android:id="@+id/myView" />
</LinearLayout>

and

<LinearLayout>
<packageName.myView android:id="@+id/myView" />
</LinearLayout>

?

I’ve created a subclass of EditText, and when instatiating it as View class=".." my Activity crashes with ClassCastException when trying to access MyView:

(MyView) myView = (MyView) findViewById(R.id.myView);

When declared as second option, everything works as expected.

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1 Answer

  1. Editorial Team

    I’m not 100% sure on this, but let me give it a go. A couple of things could be happening. The parser might not understand the class attribute correctly (e.g. it thinks it is part of a stylesheet). I am not sure how the parser handles the class attribute, since I have never seen or used it (in fact, I’ve never seen the <View> tag used either). A better explanation, though, might be this: the parser is trying to down-cast your View into packageName.myView class and fails (down-casting is always risky; up-casting is always safe).

    Regardless of what is happening, I would always use the second option you listed, <packageName.myView android:id...>, instead of using the <View> tag. Reason being, it’s redundant to use the <View> tag. Everything in this xml file must be a view (LinearLayout, Button, TextView, etc. are all descendants of the View class).

    Hope that helps. If you’re really, really curious, you could always download the source code for the parser…

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