There Are No Size Limits, Only Problem Domains
The biggest problem I have with all the Java codebases I've seen is an overabundance of class files. First of all SOLID is just a confusing reiteration of what you should already know about OOP. A class should handle a specific set of related problems. Not one problem with one method. That's just taking bad old chaining func-spaghetti C code only with the addition of all the pointless class syntax to boot. There is no size or method limit. If it makes sense to add something to an already long function or class or constructor, it makes sense. Take jQuery. It's an entire library-length toolset in a single function and there is nothing wrong with that. Whether we still need jQuery is up to reasonable debate but in terms of design, you can learn a hell of a lot about how to write effective JavaScript by understanding how JQ is architected for minimal memory usage/performance impact through slick use of closures and the prototype property.
If Java is All You Know, Dabble in Something With a Non-C-Based Syntax