Best way to learn class relationships

I am new with Java and find it very difficult to know which classes to use for what!
Even with the use of the HTML Java Specification API reference, i still find it very diffcult to do the simplist things!
For instance, in C, i can use a getc and put every character in an array and do things very logically!
But in Java, i havn't got a clue where to start!
Are there any tools that scan the complete API documentation, including return types, comments ect?
Or is there a good book that shows a hierarchy of classes that typcially work together like in a 'pattern' or template?
Thanks for any ideas!

I am new with Java and find it very difficult to know which classes to use for what!

i'm new too to it, but have no special programming background. My autodidactic way is to read tuts and books: in those i find examples that perform things - with classes or groups of classes.
That's the way i keep beeing introduced to classes and to what they perform. Sun java online tutorial is good; Bruce Eckel's Thinking in Java is a free, great book, specially because its c/c++ developers oriented.
hope this helps

Thanks Miguel! I'm going to look into your references!