Android Studio marks findviewbyid casts redundant but they aren't

Question

So I have this code: android studio marks casts as redundant.

But if I remove casts I will get compile error:

Error:(42, 29) Type mismatch: cannot convert from View to Button

Error:Execution failed for task ':app:transformJackWithJackForDebug'. com.android.build.api.transform.TransformException: com.android.builder.core.JackToolchain$ToolchainException: Jack compilation exception

What am I doing wrong? Android Studio v2.3.3

Default way is to keep casts which was required until compileSdkVersion 26. If you set compileSdkVersion to 26 you don't need to use casting. — Thracian, Oct 18 '17 at 15:36
As pointed by others this is a problem because the sdk 26, please look at this https://stackoverflow.com/questions/45577746/how-to-use-public-t-extends-view-t-findviewbyid-int-id-in-activity-android — cutiko, Oct 18 '17 at 15:52

score 1 · Answer 1 · answered Oct 18 '17 at 15:45

The declaration of View#findViewById on Android <= 25 is

View findViewById(int resId);

Requiring explicit cast for usage.

While the declaration on Android >= 26

<T> T findViewById(int resId);

It does the unsafe cast for you and returns the expected value for the assignment.

If you compile level is 26 you will be using the new method.

score 0 · Answer 2 · answered Oct 18 '17 at 15:38

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Probably the elem with Id buttonLoad is not a Button but a View.

Provide the code of the layout if it isn't the solution

answered Oct 18 '17 at 15:38

bra_racing

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score 0 · Answer 3 · answered Oct 18 '17 at 15:57

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So the solution was just cleaning up and rebuilding the project. Thanks to Fatih Ozcan

answered Oct 18 '17 at 15:57

Daniil Sudzhaev

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Android Studio marks findviewbyid casts redundant but they aren't

3 Answers3