1. In the menu bar, click Build > Generate Signed APK.

2. Select the module you would like to release from the drop down and click Next.

3. To Create a new keystore, click Create new. Now fill the required information and press ok in New Key Store.

4. On the Generate Signed APK Wizard fields are already populated for you if you just created new key store otherwise fill it and click next.

5. On the next window, select a destination for the signed APK, select the build type and click finish.

You can define the signing configuration to sign the apk in the build.gradle file.

You can define:

• storeFile : the keystore file
• storePassword: the keystore password
• keyAlias: a key alias name
• keyPassword: A key alias password

You have to define the signingConfigs block to create a signing configuration:

android {
    signingConfigs {

        myConfig {
            storeFile file("myFile.keystore")
            storePassword "xxxx"
            keyAlias "xxxx"
            keyPassword "xxxx"
        }
    }
    //....
}

Then you can assign it to one or more build types.

android {

    buildTypes {
        release {
            signingConfig signingConfigs.myConfig
        }
    }
}