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Are int value of R.id.view is always same?

  • I tried printed it in two devices and it was same.
  • I also changed name of id but still the value was same.

But will it stay the same in all scenarios?

RHS.Dev
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2 Answers2

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A View ID is generated during Compilation, so Yes the ID will be the same in each Device if the APK is the same. Pay attention that "different compilations could generate different IDs".

emandt
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For any particular app resource, the particular R class associated resource ID will be the same in all scenarios during runtime as this resource ID is generated by aapt during compile time.

From Android Documentation:

Once you provide a resource in your application, you can apply it by referencing its resource ID. All resource IDs are defined in your project's R class, which the aapt tool automatically generates. When your application is compiled, aapt generates the R class, which contains resource IDs for all the resources in your res/ directory.

Thus printing it in two devices will result the same int value, provided that the same apk is used. Also note that the resource id is final in the respective R subclass.

From this answer:

Note that aapt by default makes no attempt to keep these identifiers the same between builds. Each time the resources change, they can all get new identifiers. Each time they are built, a new R.java is created with the current identifiers so your code gets the correct values. Because of this, you must never persist resource identifiers anywhere where they can be used across different builds of your app.

Any changes to the resource might make the resource get an new R class resource ID.

Based on the way in which the R class Resource ID are calculated, as described in that answer, I think since you only changed the name of the XML resource ID, and didn't change the type of the resource nor the placement of the respective View object declaration in the respective XML file, the same R class Resource ID is being calculated.

Kalai
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