java访问同一类中dif方法中的值

Question

我试图在类中创建一个计算贷款金额的方法。这个方法应该返回“totalPay”，但它说它没有被声明，你知道为什么吗

public loan(double anualInterestRate, int numberOfYears, double loanAmount){

    double base = (double) ( loanAmount * (1+anualInterestRate/12));
    double exponent = (double) (numberOfYears * 12);
    double totalPay = (double) Math.pow(base, exponent); 
}

由于某种原因，总付款方式没有看到“totalPay”：

/**
 * 
 * @return total payment
 */
public double totalPayment(){
    return totalPay;
}

Answer 1

您正在构造函数中声明变量，使它们仅在构造函数中可见。不要这样做。在类中声明需要类可见性的类

即

class Loan {
    private double base;
    private double exponent;
    private double totalPay;

    public Loan(double anualInterestRate, int numberOfYears, double loanAmount){

        base = (double) ( loanAmount * (1+anualInterestRate/12));
        xponent = (double) (numberOfYears * 12);
        totalPay = (double) Math.pow(base, exponent); 

        // consider setting other fields with your parameters if they'll be 
        // needed elsewhere
    }