What is Design Patterns?
Basically, design patterns are categorized into two parts:

Core java (or JSE) Design Patterns.
JEE Design Patterns.

This app cover the following topics:
Core Java Design Patterns

In core java, there are mainly three types of design patterns, which are further divided into their sub-parts:

1. Creational Design Pattern

Factory Pattern
Abstract Factory Pattern
Singleton Pattern
Prototype Pattern
Builder Pattern.

2. Structural Design Pattern

Adapter Pattern
Bridge Pattern
Composite Pattern
Decorator Pattern
Facade Pattern
Flyweight Pattern
Proxy Pattern

3. Behavioral Design Pattern

Chain Of Responsibility Pattern
Command Pattern
Interpreter Pattern
Iterator Pattern

So download this app and learn Design patterns in Java.