Remove all unused resources from an android project

The Gradle build system for Android supports "resource shrinking": the automatic removal of resources that are unused, at build time, in the packaged app. In addition to removing resources in your project that are not actually needed at runtime, this also removes resources from libraries you are depending on if they are not actually needed by your application.

To enable this add the line shrinkResources true in your gradle file.

   android {
        ...

        buildTypes {
            release {
                minifyEnabled true //Important step
                shrinkResources true
            }
   }
}

Check the official documentation here,

http://tools.android.com/tech-docs/new-build-system/resource-shrinking

Since Support for the ADT in Eclipse has ended, we have to use Android Studio.

In Android Studio 2.0+ use Refactor > Remove Unused Resources...

You can easily search for unused resources from Android Studio. Just press CtrlAltShifti and type "unused resources" (without quotes). That will execute lint. Super easy way to run lint commands (and other stuff from IDE).

OR

In Android Studio Menu > Refactor > Remove Unused Resources...

Select the resources you want to remove. You can exclude resources you want to keep by right-clicking on the resource item.

Use Do Refactor to remove all Resources at once.

Update: use ⌘OptionShifti for mac

Since ADT 16 you can use Android Lint. It is really amazing tool.

Android Lint is a new tool for ADT 16 (and Tools 16) which scans Android project sources for potential bugs.

Here are some examples of the types of errors that it looks for:

• Missing translations (and unused translations)
• Layout performance problems (all the issues the old layoutopt tool used to find, and more)
• Unused resources
• Inconsistent array sizes (when arrays are defined in multiple configurations)
• Accessibility and internationalization problems (hardcoded strings, missing contentDescription, etc)
• Icon problems (like missing densities, duplicate icons, wrong sizes, etc)
• Usability problems (like not specifying an input type on a text field)
• Manifest errors and many more.

However, it has some issues (don't know if they're already fixed) and if you want to delete hundreds of supposedly unused resources I'd recommend to manually compile project several times during resource removing to be sure that Lint didn't remove something needed.