functioncall.gradle

android {
    compileSdkVersion 23
    buildToolsVersion '23.0.2'

    defaultConfig {
        applicationId "testing"
        minSdkVersion getMinSdk()
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
        }
        debug {
        }
    }
}

def getMinSdk()
{
    for (String taskName : project.getGradle().startParameter.taskNames)
    {
        if (taskName.toLowerCase().contains("release"))
        {
            return 19
        }
    }

    return 21
}