June 2022
Beginner to intermediate
672 pages
17h 23m
Japanese
Content preview from Head Firstデザインパターン 第2版 ―頭とからだで覚えるデザインパターンの基本
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246
7
章
オブジェクトアダプタとクラスアダプタ
オブジェクトアダプタとクラスアダプタ
パターンの定義は完了しましたが、まだすべてを説明したわけではありません。
実はアダプタには、オブジェクトアダプタとクラスアダプタという2種類がありま
す。いままで説明したのはオブジェクトアダプタについてで、前のページのクラス
図もオブジェクトアダプタのクラス図です。
それではクラスアダプタとは何であり、なぜクラスアダプタについては説明して
こなかったのでしょうか？
それは、クラスアダプタを実装するには多重継承が必要
なのですが、
Java
では多重継承はできないからです。しかし、だからといって今後
多重継承をサポートしているお気に入りの言語を使う際に、クラスアダプタが必要
にならないとは限りません！
多重継承のクラス図を見てみましょう。
specificRequest()
request()
Adapter
Client
Adaptee
request()
Target
アダプティに適合させるためにコ
ンポジションを使用する代わりに、
ここではアダプタはアダプティと
ターゲットクラスをサブクラス化
します。
見覚えがありますか？
そうです。クラスアダプタではターゲットとアダプ
ティをサブクラス化するのに対し、オブジェクトアダプタではコンポジショ
ンを使ってリクエストをアダプティに渡す点だけが違うのです。
オブジェクトアダプタとクラスアダプタは、アダプティに適
合させるために異なる手段（コンポジションと継承）を使っ
ています。この実装の違いは、アダプタの柔軟性にどのよう ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.