For most users, the launcher icon (sometimes referred to as the app icon) is the first impression of your app. As higher density screens on both phones and tablets gain popularity, it's important to make sure your launcher icon is crisp and high quality. To do this, make sure you’re including XHDPI (320dpi) and XXHDPI (480dpi) versions of the icon in your app.
In addition to the current launcher icon guidelines, please also refer to these additional important guidelines when creating your icons:
Note that tablets and other large screen devices request a launcher icon that is one density size larger than the device's actual density, so you should provide your launcher icon at the highest density possible. For example, if a tablet has an XHDPI screen, it will request the XXHDPI version of the launcher icon.