Java 困惑于如何在类内调用方法

所以我需要从用户那里获取输入，我已经完成了，但是我需要它打印出giveFirstClassStamps金额和givePennyStamps金额，我不知道该怎么做。 任何正确方向的帮助或指点都将不胜感激

import java.util.*;
/**
*/
public class StampMachine
{
public static final int FIRST_CLASS_STAMP_PRICE = 44;
private int balance;

/**
  Constructs a stamp machine with a zero balance.
*/
     public StampMachine() 
{ 
   balance = 0; 
}

public static void main( String[ ]  args)
{
       Scanner input = new Scanner(System.in);

      System.out.print("Enter 16-Digit Credit Card Number: ");
      String cardNumber = input.nextLine();
      System.out.print("Enter Month/Year of Expiration Date in MM/YY format: ");
      String expirationDate = input.nextLine();
      System.out.print("Stamp Purchase Amount: ");
      int dollars = input.nextInt();


}

/**
   Adds a given number of dollar bills into this machine.
   @param dollars the number of dollar bills
*/
public void insert(int dollars)
{  
    balance = balance + 100 * dollars;
}

/**
   Dispenses first class stamps for the inserted payment.
   @return the number of first class stamps
*/
public int giveFirstClassStamps()
{
   int firstClassStamps = balance / FIRST_CLASS_STAMP_PRICE;
   balance = balance - firstClassStamps * FIRST_CLASS_STAMP_PRICE;
   return firstClassStamps;
}

/**
   Dispenses penny stamps for the inserted payment.
   @return the number of penny stamps
*/
public int givePennyStamps()
{
  int pennyStamps = balance;
   balance = 0;
   return pennyStamps;      
}

---

您可以创建该类的实例，然后调用这些方法。获取输入变量后，请尝试以下操作：

StampMachine sm = new StampMachine();
sm.insert(dollars);

---

您还可以继续使用同一实例“sm”来调用其他方法。

在获得

美元后，在main中

call insert method. Modify method sigantures to pass dollars entered by the user
call giveFirstClassStamps and assign the returned value to a local variable inside main
do the same for givePennyStamps and now print the values

希望这有帮助