I read Hiroshi Yuki "Introduction to Design Patterns Learned in Java Language" (SB Creative)

Hello, I and Pu Yi.

This time, let's learn design patterns with Hiroshi Yuki's book. I did.

What is a "design pattern"?

The reason I picked up this book was a recommendation from an information-related friend. It was because I had a problem. "Because it is absolutely useful in practice" I swallowed the taiko stamp and picked it up with a big surprise. It depends.

The first thing that came to my mind was "What is a design pattern?" thing I said. This was explained at the beginning of this book.

"When I'm programming, I do the same thing as before. There are times when I notice that I'm turning back. Experience As the number increases, the next development of such "patterns" (….) You will be able to apply it to. 　Erich Gamma, Richard Helm, Ralph Johnson, John The four Vlissides have the "experience" of such developers The pattern as "internal accumulation" 　 "Design pattern"

I arranged it in the form of. "(From" Introduction ")

In short, design patterns are like "wisdom of ancestors" Things. Also, something like a "common language" between developers, That is. By the way, the four people who devised the Gang of It seems that it is called Four (GoF). looks strong.

Chapters of this book

This book is one of the 23 design patterns defined by GoF. I'm introducing each one by showing an example in a Java program. I will. The chapters are as follows.

1. 1. Iterator Count one by one
2. Adapter Cover with one skin and reuse
3. 3. Template Method Leave specific processing to subclasses Four. Leave Factory Method instantiation to subclasses Five. Singleton Only one instance
4. Prototype Copy and create an instance
5. 7. Builder Assemble a complex instance
6. 8. Abstract Factory Make a product by combining related parts
7. Separate the Bridge function hierarchy and implementation hierarchy Ten. Strategy: Switch algorithms
8. Composite Identification of container and contents
9. Decorator Identification of decoration frame and contents
10. Visitor Work while walking across the structure
11. Chain of Responsibility Responsibility
12. 15. Facade simple window
13. Mediator has only one advisor
14. Notify Observer status changes
15. Save Memento state
16. State Express the state as a class
17. Flyweight Eliminate waste by sharing the same thing twenty one. Proxy Make after you need it twenty two. Command Make a command a class twenty three. Interpreter grammar rules are expressed in classes

What I worked on

・ Copy the program posted as a sample by yourself And ran →→ As expected for each of the 23 design patterns I was able to move to ・ Explain which class plays what role I tried to read and understand

What I want to do in the future

・ Solve the leftover exercises at the end of the chapter ・ Learn how Java programs work

One last word

If there is a supplement to my article or "what I want to do in the future" If you have any recommended books for, please leave a comment. I would be happy if you could! … so, that's it for today. It was Puyi.