What all things (eg. C, C++, Java, Animation) I need to know in order to develop an android app/game?

If you are a Java Developer: For an app : You just need to know basic Java. Just look into the Android API for a day or two , this will give you enough idea to create some simple apps like calculators ,etc. Always start with basic apps , be clear of the concepts . You dont need to memorize the API (You hardly have enough time in your life to remember all that APIs) . Just be clear with the concepts. Make use of the autocomplete features of Java IDEs, it willl save you a lot of time. For developing brilliant UI , you might need to spend a bit of time . Dont heavily depend upon the drag and drop UI Builder as it doesnt provide you much of the control . For Android Game development using Java: First finish building some basic apps and be clear with the concepts. For small 2D games , you can build most of them using Views of Android APIs. For better looking 2D/3D game i suggest you use an external library or a Game Engine . I suggest you use libgdx . It is an excellent Game Engine with both 2D and 3D capabilities. If you are a Web Developer: Go for Phonegap , It provides APIs for web developers familiar with HTML / CSS and JS to write cross platform apps . But for developing games on phonegap: You can develop small 2D games. But high performance intensive games are generally not recomended to be developed because of performance issues.