How to manage code for different designs to support all devices

Question

I have an application that has already been made for large devices, such as 10-inch tablets and kiosks. I did the same design for mobile phones, but it didn’t look very good, so I decided to move the mobile device to a material design, and the rest of the devices (tablets and kiosks) will remain the same.

I know how I can create different layouts for different devices, that is, ordinary, large and x-large, but the code bothers me. So basically the following are my bewilders ....

• What is the best way to judge which device works in my application, so I have to run some methods based on this, because my usual device follows the material design and contains some widgets that are missing from the design of tablets and kiosks, i.e. RecyclerView (for some purposes)?
• I searched a lot for this problem and came to the conclusion that there are two ways to support multiple devices 1> make two separate apks, 2> Make one apk and check the code to distinguish between devices, but, as I said above, in paragraph 1, that I have a material design in regular devices, and it's a completely redesigned one in terms of widgets and layouts, fragments and even navigation, so what would you suggest is the best way to handle this?
• If I make 1 apk and put the verification code, then I have to say that I have a ton of code and resources, and in any case (if the device is normal and large) some resources and classes will never be used and will make the apk size larger What is the best way to get around this?

I also looked through stackOverflow and only came up with these two links, which were close to my question, but the rest of the links are about different layouts, not the code:

• Android app for phone and tablet: 1 or 2 applications?
• Create a different layout for your Android phone and tablet

Hope I calmly speak in my question, please answer my question with some genuine reasons and links.

Answer 1

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Gradle productFlavors apk :

productFlavors {
    bigtablet {
        buildConfigField "String", "deviceType", "\"bigtable\""
    }
    smalltablet {
        buildConfigField "String", "deviceType", "\"smalltable\""
    }
}

BuildConfig.deviceType , apk. Gradle apk.

apk. .

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Answer 2

, Android, . , RecyclerView . layout-xxx APK API - .