Recompile with -Xlint in Android Studio

The message suggest you recompile with args -Xlint to get more warning details, add these code to build.gradle:

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

Then you can fix warnings by detailed messages.
For example, you can replace deprecated method with new method(there always been a new method since old method has been deprecated) .

However, sometimes we don't want change our code for some reasons, we just want get rid of compile warning, you can add @SuppressWarnings("deprecation") in front of the deprecated method.

You need to add the following inside your app level buld.graddle file

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

If for some reasons you need to continue using a deprecated API you can just suppress the warning. You could annotate the deprecated method with the

@SuppressWarnings("deprecation")

annotation.

post link

If you are facing issue in generating signed apk, you can try to do this in your build.gradle(app)

android {
    lintOptions {
        checkReleaseBuilds false
    }
}

It is some error in the project, maybe from XML files. Disabling lintOptions is not a correct solution. Find the error and fix the problem, to do this run below command in Android Studio Terminal

Windows

gradlew assembleDebug --stacktrace

MAC

./gradlew assembleDebug --stacktrace

You can manually run configured lint and other IDE inspections by selecting Analyze > Inspect Code. The results of the inspection appear in the Inspection Results window. see details here:

The message suggests to recompile with -Xlint flag in command-line, to get more issue details, but even if you do, the next log may ask for --stacktrace flag.

In build.gradle file, do something like:

import org.gradle.api.logging.configuration.ShowStacktrace
allprojects {
    // Same as passing --stacktrace option.
    gradle.startParameter.showStacktrace = ShowStacktrace.ALWAYS

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

Note that the import may not be required (just imported to be clear).

Also as y4n9b0 said; Then you can use warnings' details to fix issues.
For example, you can replace deprecated method with new method (I mean, there must be a new-method, since old-method has been deprecated).

But sometimes for backward compatibility, we don't want change our code, and just want to get rid of compile-time warnings; simply add in front of the deprecated method:

@SuppressWarnings("deprecation")