Android Modular Programming

Question

My Problem might not be valid. And the points I mention here might be little incorrect as I am neither perfect nor expert.

I have a shopping application and I want to start building a modular application. Like I want to add Affiliate User( the module which adds certain functionality or this will display some extra pages in an application) in the application.

A similar situation happens in the Frameworks: We add and enable the certain module and in return framework load everything as required.

for this, I want following changes like:

1. add an entry in the NavigationView displaying "Affiliate Label".
2. load fragments (just adding one more fragment for one more label/option from navigation view).

Let's say I have a library project that contains a Fragment and all relevant code.

How can I build the application automatically let's say just by writing "true" somewhere in the XML?

Automatically here means label is added, Intents are performed on click of label etc.

<Modules>
<enable>true/false</enable>
</Modules>

This is just the simple scenario.

Answer 1

You could do this (like everywhere when it comes to writing code) in many possible ways.

1. The "file" way: Make a new file named something like modules.txt with key value pairs. Load the file and check whether a module is enabled or not.
2. The "Constant" way: Make an abstract class which only contains public static final variables which describe your modules.
3. The "package manager" way: See create Android Application plugins/extensions (apk)
4. The "multiple" apk way: Note that this is not reccomended!

we encourage you to develop and publish a single APK

multiple apk support

Answer 2

To add to codewing's answer, you can also use Gradle's resource management capabilities to accomplish this, so you only ever need to look in one place for an enabled/disabled status.

For this, you have 2 solid options.

The first starts with a boolean which can be split by flavor:

<bool name="module_x_enabled">true</bool>

The second would be to inject your values into a String resource after Gradle merges the resources by adding something like this to your build.gradle file, then comparing that enabled value:

<string name="module_x_enabled">MODULE_X_ENABLED_PLACEHOLDER</string>


android.applicationVariants.all{ variant ->
    variant.mergeResources.doLast{    
        replaceInValues(variant, 'MODULE_X_ENABLED_PLACEHOLDER', MODULE_X_ENABLED)
    }
}

def replaceInValues(variant, fromString, toString) {
    File valuesFile = file("${buildDir}/intermediates/res/merged/${variant.dirName}/values/values.xml")
    String content = valuesFile.getText('UTF-8')
    content = content.replaceAll(fromString, toString)
    valuesFile.write(content, 'UTF-8')
}

Where MODULE_X_ENABLED would be a setting in your gradle.properties file like:

MODULE_X_ENABLED=true 

Edit: or better yet,

Why not pull the settings from some kind of server so that you don't need to rebuild and relaunch to update a client's module?