Question

我有一个类钱包，它扩展到3个不同的钱包PaypalWallet，BankWallet和ChequeWallet。每个具有不同属性的都保存超类属性。

这些钱包用于Payout，它可以扩展2笔付款，PaymentBank和PayoutCheque。

public class Payout {
    @Id private String id;
    private String userId;
    protected Wallet userWalletInfo;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public Wallet getUserWalletInfo() {
        return userWalletInfo;
    }

    public void setUserWalletInfo(Wallet userWalletInfo) {
        this.userWalletInfo = userWalletInfo;
    }
}

如果我在ChequePayout中继承了这个类，我如何指定userWalletInfo应该是ChequeWallet的一个实例？类似于扩展课程？

我的第一个念头是覆盖了setter，就像这样：

public class PayoutCheque extends Payout {
    private String serialNumber;
    private ChequeStatus status;

    public String getSerialNumber() {
        return serialNumber;
    }

    public void setSerialNumber(String serialNumber) {
        this.serialNumber = serialNumber;
    }

    public ChequeStatus getStatus() {
        return status;
    }

    public void setStatus(ChequeStatus status) {
        this.status = status;
    }

    @Override
    public void setUserWalletInfo(Wallet userWalletInfo) {
        if (userWalletInfo instanceof ChequeWallet) {
            super.setUserWalletInfo(userWalletInfo);
        }
        else {
            //throw exception
        }
    }
}

然而，我觉得这不是正确的做法，或者我错过了一些重要的事情。

Answer 1

听起来你正在寻找泛型。

private class Wallet {
}

private class ChequeStatus {
}

private class ChequeWallet extends Wallet {
}

public class Payout<W extends Wallet> {
    private String id;
    private String userId;
    protected W userWalletInfo;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public Wallet getUserWalletInfo() {
        return userWalletInfo;
    }

    public void setUserWalletInfo(W userWalletInfo) {
        this.userWalletInfo = userWalletInfo;
    }
}

public class PayoutCheque extends Payout<ChequeWallet> {
    private String serialNumber;
    private ChequeStatus status;

    public String getSerialNumber() {
        return serialNumber;
    }

    public void setSerialNumber(String serialNumber) {
        this.serialNumber = serialNumber;
    }

    public ChequeStatus getStatus() {
        return status;
    }

    public void setStatus(ChequeStatus status) {
        this.status = status;
    }

    @Override
    public void setUserWalletInfo(ChequeWallet userWalletInfo) {
        super.setUserWalletInfo(userWalletInfo);
    }
}

Answer 2

if(userWalletInfo.getClass().equals(ChequeWallet.class)){

}

扩展超类属性

2 个答案: