public class Loan {
	private double annualInterestRate;
	private int numberOfYears;
	private double loanAmount;
	private java.util.Date loanDate;
	
	public Loan() {
		this(2.5, 1, 1000);
	}
	public Loan(double annualInterestRate, int numberOfYears, double loanAmount) {
		this.annualInterestRate = annualInterestRate;
		this.numberOfYears = numberOfYears;
		this.loanAmount = loanAmount;
		loanDate = new java.util.Date();
		judge();
	}
	public void judge() throws IllegalArgumentException{
		if(this.loanAmount<=0) {
			throw new IllegalArgumentException("贷款总额小于等于0!");
		}
		if(this.annualInterestRate<=0) {
			throw new IllegalArgumentException("利率小于等于0!");
		}
		if(this.numberOfYears<=0) {
			throw new IllegalArgumentException("贷款年数小于等于0!");
		}
		
	}
	public double getAnnualInterestRate() {
		return annualInterestRate;
	}
	public void setAnnualInterestRate(double annualInterestRate) {
		this.annualInterestRate = annualInterestRate;
		judge();
	}
	public int getNumberOfYears() {
		return numberOfYears;
	}
	public void setNumberOfYears(int numberOfYears) {
		this.numberOfYears = numberOfYears;
		judge();
	}
	public double getLoanAmount() {
		return loanAmount;
	}
	public void setLoanAmount(double loanAmount) {
		this.loanAmount = loanAmount;
		judge();
	}
	public double getMonthlyPayment() {
		double monthlyInterestRate = annualInterestRate / 1200;
		double monthlyPayment = loanAmount * monthlyInterestRate / (1 - (1 / Math.pow(1+monthlyInterestRate, numberOfYears * 12)));
		return monthlyPayment;
	}
	public double getTotalPayment() {
		double totalPayment = getMonthlyPayment() * numberOfYears * 12;
		return totalPayment;
	}
	public java.util.Date getLoanDate(){
		return loanDate;
	}
}