Inject dynamic host IP address in with Gradle

build.gradle

...
android {
 
    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 19
        buildConfigField "String", "LOCAL_IP", '\"' + getLocalIp("eth0") + '\"'
    }
}

// Get the ip address by interface name
def getLocalIp(String interfaceName) {
    NetworkInterface iface =  NetworkInterface.getByName(interfaceName);
    for (InterfaceAddress address : iface.getInterfaceAddresses()) {
        String ip =  address.getAddress().getHostAddress()
        if (ip.length() <= 15) {
            return ip;
        }
    }
}

ServerUtil.java

private static final String HOST_EMULATOR = "10.0.2.2";
private static final String HOST_PRODUCTION = "example.com";
	
public static String getHost() {
	if (BuildConfig.DEBUG) {
		return (Build.PRODUCT).contains("sdk") ? HOST_EMULATOR : BuildConfig.LOCAL_IP;
	}
	return HOST_PRODUCTION;
}