Create a signed build apk using build.gradle

You can create a signed build apk via regular method.
Here we learn another way to generate signed build apk through build.gradle:

android {
      signingConfigs {
                release {
                      storeFile file ("release.keystore")
                      storePassword "******"
                      storeAlias "********"
                      keyPassword "*******"
                }
        }
        buildTypes {
                release {
                      signingConfig signingConfigs.release
                 }
         }
}

Now your signed release apk is ready.