What is "proguard-android"
The Proguard tool shrinks, optimizes, and obscures your code by removing the code used and renaming classes, fields, and methods with semantically obscure names. The result is a smaller apk file size. Which is harder to reverse engineer. Because Proguard makes your application harder to reverse engineer, it is important to use it when your application utilizes features that are security sensitive, such as when you are licensing your applications.
Proguard is integrated into the Android building system, so you don’t have to call it manually. Proguard only runs when you create your application in version mode, so you don’t have to deal with obfuscated code when you create your application in debug mode. Having Proguard running is completely optional but highly recommended.
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