面向对象编程,getter没有从另一个类获取私有变量

Question

该计划应在12个月和24个月后计算2个账户的利息.这很好用.我的问题是利率的getter/setter不起作用,所以当利率在另一个类私有变量中保存为0.1时,我无法从主类中打印出来.

public class testAccountIntrest{
    //main method
    public static void main(String[] args) {
        //creating objects
        Account account1 = new Account(500);
        Account account2 = new Account(100);


        //printing data
        System.out.println("");
        System.out.println("The intrest paid on account 1 after 12 months is " + account1.computeIntrest(12));
        System.out.println("");
        System.out.println("The intrest paid on account 1 after 24 months is " + account1.computeIntrest(24));
        System.out.println("");
        System.out.println("");
        System.out.println("The intrest paid on account 2 after 12 months is " + account2.computeIntrest(12));
        System.out.println("");
        System.out.println("The intrest paid on account 2 after 24 months is " + account2.computeIntrest(24));
        System.out.println("");
        System.out.println("The intrest rate is " + getIntrest());


        }//end main method
    }//end main class

class Account {
    //instance variables
    private double balance;
    private double intrestRate = 0.1;

    //constructor
    public Account(double initialBalance) {
        balance = initialBalance;
    }

    //instance methods
    public void withdraw(double amount) {
        balance -= amount;
    }
    public void deposit(double amount) {
        balance += amount;
    }
    public double getBalance() {
        return balance;
    }
    public void setIntrest(double rate) {
        intrestRate = rate;
    }

    public double getIntrest() {
        return intrestRate;
    }

    public int computeIntrest(int n) {
        double intrest = balance*Math.pow((1+intrestRate),(n/12));
        return (int)intrest;
    }
}

Answer 1

由于编译器无疑是在告诉你,你的testAccountIntrest类不具有一个名为方法getInterest().所以这一点在该类的上下文中无法做任何事情:

getInterest()

但是,你的Account班级确实有这种方法.并且您在该范围内有两个Account 对象:

Account account1 = new Account(500);
Account account2 = new Account(100);

所以你可以在那些对象上调用该方法:

account1.getInterest()

要么:

account2.getInterest()

基本上,您必须告诉代码您正在调用方法的对象.它无法自行解决.