The "Gang of Four" design patterns book was a seminal piece of work that helped introduce Object Oriented (OO) to the software development world in the 90s. Understanding these design patterns will help your own software designs, especially if you are new to object-oriented programming.
Check out this presentation PDF for a detailed walkthrough of the GOF patterns. The presentation has accompanying exercises to further your learning. They are located in the
exercises folder while the exercise source solutions are in the
Note: The Java source code for this tutorial was constructed using early Java, so please excuse the use of Vectors and such. That said, the source compiles and runs in Java 8 and provides a good way to understand these famous design patterns.
Here's the link to buy the book.