Recompile with -Xlint in Android studio

Staying out of deprecated methods is useful, so your app won’t run in some compatibility mode on the device. Plus having clean build output is also nice 🙂

While building an app, Gradle may produces some warnings telling you that some input files are using unchecked or unsafe operations or they are overriding a deprecated API.

Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

As the message suggest, we should recompile with -Xlint to get more details about the warnings.

In the app level build.gradle file

app level build.gradle file

we should add a section labelled  allprojects{}(if not already present).

In the allprojects{} section we will instruct Gradle to apply custom compiler arguments for each task involving  Java code compilation.

allprojects {
    tasks.withType(JavaCompile) {
        options.compilerArgs << "-Xlint:unchecked" << "-Xlint:deprecation"

Now each time we build our app we will get detailed output of the unchecked or unsafe operations and the deprecated API we are using.

Tip: if for some reason we want to continue using a deprecated API and just suppress the warnings, we could annotate the deprecated method with the



Auto ‘versionCode’ increment when building production apk’s

Since I adopted Fabric as a way to monitor vital app stats such as ‘Time in App per User‘ and it’s Beta distribution platform to distribute test builds, increasing APK’s versionCode numbers became a tedious task.

I decided to simplify the things by letting Gradle to do auto versionCode increments when producing release APK’s

Our implementation of build number increments will consist of a property file named located in the root folder of our project.

The property file will contain 2 variables, one defining the version name such as “2.3” and one defining the version code such as 15


In our app module build.gradle file


we will define a function which takes care of retrieving the a bough mentioned values from the properties file and increment the VERSION_CODE if needed.

 * Get's value from '' file
 * @param varName the name of the variable which value we wan't to get.
 * @return the variable value.
def getVersionPropertiesValue(def varName)
    def propertiesFile = file('')
    if(!propertiesFile.canRead()) {
        throw new GradleException("Could not read " +
    Properties properties = new Properties();
    properties.load(new FileInputStream(propertiesFile))
    def propertyValue = properties[varName]
    if(varName == 'VERSION_CODE')
        // If we are building release increment the version code
        List gradleTasksNames = gradle.startParameter.getTaskNames();
        for(String taskName : gradleTasksNames)
                propertyValue = propertyValue.toInteger() + 1
                properties[varName] = propertyValue.toString()
      , null)
    return propertyValue

In the defaultConfig section of the gradle build script we will call this function to retrieve values for the versionName and versionCode of our app.

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId ""
        versionCode Integer.valueOf(getVersionPropertiesValue('VERSION_CODE'))
        versionName getVersionPropertiesValue('VERSION_NAME')
        minSdkVersion 14
        targetSdkVersion 28

Now each time a release build is made, the version code will increment automatically. If we want to change the version name we can do so by changing the value of VERSION_NAME property.