java - Loan 类型的方法 Loan(double, int, double) 未定义？

Question

谁能帮我看看我在哪里错过了这个？我试图将贷款类调用到主方法，并检查我的异常处理是否正确。我对此非常陌生，确切地说是第六周，并且可以使用所有可能的建设性帮助。提前致谢!

package loan;
import java.util.Scanner;

public class Loan {

public static void main(String[] args) {
    try {
        Loan(2.5, 0, 1000.00);
    }
    catch (IllegalArgumentException ex) {
        ex.getMessage();
    }
}

Scanner input = new Scanner(System.in);
double annualInterestRate;
int numberOfYears;
double loanAmount;
private java.util.Date loanDate;

public Loan() {
    this(2.5, 0, 1000);
}
public Loan(double annualInterestRate, int numberOfYears, double loanAmount) {
    this.annualInterestRate = annualInterestRate;
    this.numberOfYears = numberOfYears;
    this.loanAmount = loanAmount;
    loanDate = new java.util.Date();
}


public double getAnnualInterestRate() {
    if (annualInterestRate > 0)
        return annualInterestRate;
    else
        throw new IllegalArgumentException("Interest rate cannot be zero or negative.");
}

public void setAnnualInterestRate(double annualInterestRate) {
    this.annualInterestRate = annualInterestRate;
}

public int getNumberOfYears() {
    if (numberOfYears > 0)
        return numberOfYears;
    else
        throw new IllegalArgumentException("Number of years cannot be zero");
}

public void setNumberOfYears(int numberOfYears) {
    this.numberOfYears = numberOfYears;
}

public double getLoanAmount() {
    if (loanAmount > 0)
        return loanAmount;
    else
        throw new IllegalArgumentException("Loan amount cannot be zero");
}

public void setLoanAmount(double loanAmount) {
    this.loanAmount = loanAmount;
}

public double getMonthlyPayment() {
    double monthlyInterestRate = annualInterestRate/1200;
    double monthlyPayment = loanAmount * monthlyInterestRate / (1 - (Math.pow(1/(1 + monthlyInterestRate), numberOfYears *12)));
    return monthlyPayment;
    }
public double getTotalPayment() {
    double totalPayment = getMonthlyPayment() * numberOfYears * 12;
    return totalPayment;
}

public java.util.Date getLoanDate() {
    return loanDate;
}
}

Answer 1

尚不清楚您希望它在 main 中执行什么操作:

try {
    Loan(2.5, 0, 1000.00);
}

我怀疑你的意思是它是一个构造函数调用:

try {
    new Loan(2.5, 0, 1000.00);
}

您的帖子表明术语有些困惑，这可能导致了此问题:

I am trying to get the loan class called to the main method

你不调用一个类。您调用构造函数或方法。你的意思是:

I am trying to make the main method call the constructor for the Loan class.

此时，您可能会更清楚地知道您需要new。