Both are drastically different, both in concept and use case. If you want to focus on Software Development, learn Java, if you want to do lower level programming, learn C. If you want to do game dev, learn C# (which is pretty much the same as Java, both syntax wise and functionality wise, with the only difference being at how it is executed).
C is a functional programming language, whereas Java is object oriented.
Learn what those concepts mean, learn what they are used for, and then decide.
If you aren't quite sure what you want to do, learn C. You will learn most programming languages fairly easily if you can master C.