Instanceof Java 问题：我无法使 if 语句成真

问题描述

你好，我有 3 个类 Account ，InvestmentAccount，Branch

我的 InvestmentAccount 类继承了 Account Class ，我的 Branch 类有一个 Account 数组和一些方法，现在除了使用关键字“instanceof”的方法外，一切似乎都有效 我想要做的是，如果此帐户是 InvestmentAccount，则获取其投资并存储它，然后在该方法获取所有投资后返回它 发生的事情是它总是返回 0.0，这很奇怪，就像 if 语句永远不会为真

这是方法：

public double totalInvestment() {
    double investmentsSum = 0;
    for (int i = 0; i < howMany; i++) {
        if (arr[i] instanceof InvestmentAccount)
            investmentsSum += ((InvestmentAccount)arr[i]).getInvestment();
    }
    return investmentsSum;
}

这是我的帐户类：

    public class Account {
    protected long accountNo;
    protected long customerId;
    protected String customerName;
    protected double balance ;

    public Account(long accountNo,long customerId,String customerName,double balance) {
        this.accountNo = accountNo;
        this.customerId = customerId;
        this.customerName = new String(customerName);
        this.balance = balance;
    }

    public Account(Account other) {
        this.accountNo = other.accountNo;
        this.customerId = other.customerId;
        this.customerName = other.customerName;
        this.balance = other.balance;
    }

    public long getAccountNo() {
        return accountNo;
    }

    public long getCustomerId() {
        return customerId;
    }

    public String getCustomerName() {
        return customerName;
    }

    public double getBalance() {
        return balance;
    }

    public void setAccountNo(long accountNo) {
        this.accountNo = accountNo;
    }

    public void setCustomerId(long customerId) {
        this.customerId = customerId;
    }

    public void setCustomerName(String customerName) {
        this.customerName = customerName;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    public boolean equals(Account a){
        if(a.getAccountNo() == this.accountNo)
            return true;
        return false;

    }




    @Override
    public String toString() {
        return "Account{" +
                "accountNo=" + accountNo +
                ",customerId=" + customerId +
                ",customerName='" + customerName + '\'' +
                ",balance=" + balance +
                '}';
    }
}

这是我的 InvestmentAccount 类：

    public class InvestmentAccount extends Account {
    private double investment;
    private Date start;
    private Date end;
    private double rate;

    public InvestmentAccount(long accountNo,double balance,double investment,Date start,Date end,double rate) {
        super(accountNo,customerId,customerName,balance);
        super.accountNo = accountNo;
        this.investment = investment;
        this.start = start;
        this.end = end;
        this.rate = rate;
    }


    public double getInvestment() {
        return investment;
    }

    public Date getEnd() {
        return end;
    }

    public Date getStart() {
        return start;
    }



    public double getRate() {
        return rate;
    }

    public void setEnd(Date end) {
        this.end = end;
    }

    public void setInvestment(double investment) {
        this.investment = investment;
    }

    public void setRate(double rate) {
        this.rate = rate;
    }

    public void setStart(Date start) {
        this.start = start;
    }

    @Override
    public String toString() {
        return "InvestmentAccount{" +
                "investment=" + investment +
                ",start=" + start +
                ",end=" + end +
                ",rate=" + rate +
                "} " + super.toString();
    }
}

欢迎任何建议或帮助，提前致谢

解决方法

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