How to learn Designing in Java

In your Java development work, you should have had ample time to consider the pros and cons of the language features you have chosen to use. If you haven't been using abstract classes and interfaces, for example, or have not been considering them critically in your implementation work, then you should start doing that.

Contemplating how the Java Standard Edition APIs coerce you into using them thru abstract classes and interfaces should convey at least a modicum of insight. So is evaluating the pain points in your development work, and asking yourself (a) if there's a way to alleviate them, and, if so, (b) why haven't you been doing it.

Finding an Object Oriented Design course at a local college might also be useful in integrating theory with your development experience.

But, definitely, looking at your work with a more critical eye is key. Find and read blogs that discuss OOD or OOP. Read and contribute to the discussions in comp.lang.java.programmer on USENET.

I think these few things may help

1. Select any open source project of your choice - Spring or any Apache project and try and understand how they do their coding. Follow their source code and if possible try to participate. What kind of patterns they use and try to understand why they do that. These projects can be a reference, a baseline for you to get started.

2. Read the book "Domain Driven Design" by Eric Evans, atleast the first few chapters that talks about entities, value objects etc.

Thanks for the tips I used to code Java in university for 1-2 years than switched to php and used it for 5 years now I find it very hard to get back to Java.