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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public class HouseBlend extends Beverage {
public HouseBlend() {
description = "
ハウスブレンドコーヒー
";
}
public double cost() {
return 0.89;
}
}
public class Espresso extends Beverage {
public Espresso() {
description = "
エスプレッソ
";
}
public double cost() {
return 1.99;
}
}
飲み物をコーディングする
これで基底クラスが完成したので、飲み物を実装しましょう。まずはエスプレッソから始めます。
それぞれの飲み物の説明を設定するほか、cost()メソッドも実装する必要があります。
これは飲み物なので、まず
Beverage
クラスを拡張します。
説明をクラスのコンストラクタで設定しま
す。説明インスタンス変数を
Beverage
から
継承していることを思い出してください。
最後にエスプレッソの料金を計算する必要があります。この
Espresso
クラスではコンディメントの追加は心配しなくていいので、エスプレッ
ソの料金
1.99
ドルを返すだけでよいのです。
これは別の飲み物です。ここでは、「ハウス
ブレンドコーヒー」という適切な説明を設
定し、正しい料金
89
セントを返すだけです。
他の
2
つの
Beverage
クラス（
DarkRoast
と
Decaf
）も全
く同じ方法で作成できます。
スタ
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