第1部第9章私たちの生活の時間

<現在実装が必要なリスト>

ドル5+10 CHF=10ドル(為替レートが2:1の場合)

$5 * 2 = $10

amount私有化

ドル副作用

金銭四捨五入

equals()

hashCode()

Equal null

Equal object

~~ 5CHF * 2 = 10CHF~~

ドル/Franc重複除外

ドル

共通equals

公共時間

FrancとDollarの比較

通話?

不要なサブクラスを除去するために,通貨概念を導入する.

money classにcurrency()メソッドを宣言します.

abstract class Money {
    protected int amount;
    abstract Money times(int multiplier);
    abstract String currency();
    
    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount) {
        return new Dollar(amount);
    }

    static Money franc(int amount) {
        return new Franc(amount);
    }
}

は、2つのサブクラスにおいてcurrency()を実装する.

// Franc
public class Franc extends Money{

    public Franc(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return new Franc( amount * multiplier);
    }

    @Override
    String currency() {
        return "CHF";
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

// Dollar
public class Dollar extends Money {
    public Dollar(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return new Dollar( amount * multiplier);
    }

    @Override
    String currency() {
        return "USD";
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

2つのクラスを含む同じ実装を望んでいます.
->インスタンス変数に通貨を格納し、メッサーがそれだけを返すようにします.

// Money
abstract class Money {
    protected int amount;
    abstract Money times(int multiplier);
    protected String currency;

    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount) {
        return new Dollar(amount);
    }

    static Money franc(int amount) {
        return new Franc(amount);
    }
}

// Franc
public class Franc extends Money{
    private String currency;
    public Franc(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return new Franc( amount * multiplier);
    }

    Franc(int amount) {
        this.amount = amount;
        currency = "CHF";
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

// Dollar
public class Dollar extends Money {
    private String currency;
    public Dollar(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return new Dollar( amount * multiplier);
    }

    Dollar(int amount) {
        this.amount = amount;
        currency = "USD";
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

これで間違いだ.先に置いておいて、まずtimes()を整理します.

// Money
abstract class Money {
    protected int amount;
    abstract Money times(int multiplier);
    protected String currency;

    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount) {
        return new Dollar(amount, "USD");
    }

    static Money franc(int amount) {
        return new Franc(amount, "CHF");
    }
}

// Franc
public class Franc extends Money{
    private String currency;
    public Franc(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return Money.franc(amount * multiplier);
    }

    Franc(int amount, String currency) {
        this.amount = amount;
        this.currency = currency;
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

// Dollar
public class Dollar extends Money {
    private String currency;
    public Dollar(int amount) {
        this.amount = amount;
    }

    Money times(int multiplier) {
        return Money.dollar( amount * multiplier);
    }

    Dollar(int amount, String currency) {
        this.amount = amount;
        this.currency = currency;
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

現在、2つの成長は同じであるため、実装をより高いレベルに向上させることができる.

// Money
abstract class Money {
    protected int amount;
    abstract Money times(int multiplier);
    protected String currency;

    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    Money(int amount, String currency) {
        this.amount = amount;
        this.currency = currency;
    }

    static Money dollar(int amount) {
        return new Dollar(amount, "USD");
    }

    static Money franc(int amount) {
        return new Franc(amount, "CHF");
    }
}

// Franc
public class Franc extends Money{
    private String currency;

    Money times(int multiplier) {
        return Money.franc(amount * multiplier);
    }
    Franc(int amount, String currency) {
        super(amount, currency);
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

// Dollar
public class Dollar extends Money {
    private String currency;

    Money times(int multiplier) {
        return Money.dollar( amount * multiplier);
    }

    Dollar(int amount, String currency) {
        super(amount, currency);
    }
    @Override
    String currency() {
        return currency;
    }

    public boolean equals(Object object) {
        Money money = (Money) object;
        return amount == money.amount;
    }
}

<現在実装が必要なリスト>

ドル5+10 CHF=10ドル(為替レートが2:1の場合)

$5 * 2 = $10

amount私有化

ドル副作用

金銭四捨五入

equals()

hashCode()

Equal null

Equal object

~~ 5CHF * 2 = 10CHF~~

ドル/Franc重複除外

ドル

共通equals

公共時間

FrancとDollarの比較

通話?

削除

testFrancマルチレプリケーション

私たちは今まで.

の大きな設計アイデアを処理する際、困難のため、より小さな仕事をしました.

の他の部分を発信者に移行し、2つの生成者をマッチングさせる.

回()の再包装を一時停止しました.

は、同じ生成者をより高いレベルに移行する.