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How to speed up gradle build time if multidex enabled

Hello Android Coders, so we all use Android studio with gradle to build android projects. But after adding some dependency and enabling multidex support then Android studio will take up to 5 minutes to build project every time. Which is too annoying to wait for long time to see new changes.

We can also enable instant run feature of android studio but instant run decrease performance of Desktop/Laptop.

So the better way is to enable multi flavor. Which means build for multiple devices separately. Android studio build 1 apk for all devices/Android versions. So we can specify 1 device to target for development. (Because we use 1-2 device to run and debug apps.) Then why we build apk for all android versions if we are testing on 1 android version. But don’t worry Release apk will be for all android versions. And will be supported for all devices. And while building Release apk it will take normal time (4-5 minutes). But its OK because we will build Release apk only 1 time. And we can wait for 4-5 minutes to build release apk. This will decrease build time from 5-6 minutes to 20-30 seconds only. Which is great. So do the following changes in build.gradle file of module (not in Project build.gradle file)

1. Open build.gradle file of your project module. (by default its app). and do below changes

android {
    compileSdkVersion 24
    buildToolsVersion "24.0.2"
        defaultConfig {
            applicationId "com.edablogs.showcase"
            targetSdkVersion 24
            minSdkVersion 16
            versionCode 1
            versionName "1.0"
            renderscriptTargetApi 22
            multiDexEnabled true
        }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }

    }
}

so add new node inside ‘android’ node named ’productFlavors’, this node is used to make project for multiple devices or multiple CPU’s. and inside ”productFlavors” node we need to create another node with any name. and inside those child nodes we will specify minSdkVersion only. and shift ”defaultConfig” node inside ”buildTypes” node. so your code will look like this

android {
    compileSdkVersion 24
    buildToolsVersion "24.0.2"

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        defaultConfig {
            applicationId "com.edablogs.showcase"
            targetSdkVersion 24
            versionCode 1
            versionName "1.0"
            renderscriptTargetApi 22
            multiDexEnabled true
        }
    }
    productFlavors {
        // Define separate dev and prod product flavors.
        dev {
            // dev utilizes minSDKVersion = 21 to allow the Android gradle plugin
            // to pre-dex each module and produce an APK that can be tested on
            // Android Lollipop without time consuming dex merging processes.
            minSdkVersion 21
        }
        prod {
            // The actual minSdkVersion for the application.
            minSdkVersion 16
        }
    }
}

And now click on product variant option on left bottom corner, and choose devDebug in build flavor. (as shown in below screenshot.)

Now run your app on lollipop or higher version of android. And you will see result that build time is decreased.

How it works ?

Reason behind this trick is MultiDex. on Old version of Android (less than sdk version 21) we need to use multidex library to enable multidex. and this library increase build time. But after releasing SDK 21 android had added multidex feature by default. we just need to write “multiDexEnabled true” in build.gradle and everything is done. That’s why we have made two variants of our project 1 have min sdk version 21 and other have actual min sdk version of your app. and we will select default build from ”buildVariants” so Android Studio will build our project as SDK 21 and Android Studio will not compile ”MultiDex library” which will take only 20-30 seconds to build a project. And when you build your app for Release then original build will be done which will take 5-6 minutes.