What methods are being used to protect this Android APK: Reflection? Encryption? How do I reverse engineer it and analyze it?

Question

I know the basics to java programming, but I\'m new to reverse engineering APKs, so explanations would be nice!

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I have an APK file file, but not the Java source. A

Answer 1

The ProGuard tool shrinks, optimizes, and obfuscates your code by removing unused code and renaming classes, fields, and methods with semantically obscure names. The result is a smaller sized .apk file that is more difficult to reverse engineer.

You could read more here: http://developer.android.com/intl/es/tools/help/proguard.html