Java调用不同类中的void方法到主类？

huangapple
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英文:

Java calling a void method in a different class to a main class?

问题

以下是翻译好的部分：

  1. // 原始的方法
  2. public ParkingTicket issueParkingTicket(ParkedCar car, ParkingMeter meter) {
  3.     if (isParkingTimeExpired(car, meter) == true) {
  4.         ParkingTicket ticket = new ParkingTicket(officerName, officerBadgeNumber, car.getLicensePlateNumber(), calculateFine(car, meter));
  5.         ticket.displayDetails();
  6.         return ticket;
  7.     } else {
  8.         return null;
  9.     }
  10. }
  12. // 修改后的方法
  13. public void issueParkingTicket(ParkedCar car, ParkingMeter meter) {
  14.     if (isParkingTimeExpired(car, meter) == true) {
  15.         ParkingTicket ticket = new ParkingTicket(officerName, officerBadgeNumber, car.getLicensePlateNumber(), calculateFine(car, meter));
  16.         ticketList.add(ticket);
  17.         ticket.displayDetails();
  18.     }
  19. }
  21. // 主驱动类
  22. public class Driver {
  23.     public static void main(String[] args) {
  24.         ParkedCar myCar1 = new ParkedCar("Fred", "toyota", 2013, "Z1234", 25);
  25.         myCar1.displayDetails();
  27.         ParkingMeter myMeter1 = new ParkingMeter("SYDNEY", true, 0.15, 70);
  28.         myMeter1.displayDetails();
  30.         PoliceOfficer officer1 = new PoliceOfficer("John doe", "DMX1234");
  31.         officer1.issueParkingTicket(myCar1, myMeter1); // 不再有返回值
  33.         // 这是你遇到错误的部分：ParkingTicket ticket = officer1.issueParkingTicket(myCar1, myMeter1);
  34.     }
  35. }

请注意，我已按照你的要求仅提供代码部分的翻译，不包括其他内容。如果你还有进一步的问题或需要其他帮助，请随时提问。

英文:

I have a method to issue a parkingTicket in my officer class,

  1. public ParkingTicket issueParkingTicket(ParkedCar car,ParkingMeter meter){
  2.         
  3.         if(isParkingTimeExpired(car,meter) == true){
  4.           ParkingTicket ticket = new ParkingTicket(officerName,officerBadgeNumber,car.getLicensePlateNumber(),calculateFine(car,meter));
  5.           ticket.displayDetails();
  6.           
  7.          
  8.           return ticket;
  9.             } else
  10.              { return null;
  11.     }           
  12.    }

I was asked to modify it in a way to have it not return anything so i made it void, so I did it this way

  1.  public void issueParkingTicket(ParkedCar car,ParkingMeter meter){
  2.         
  3.         if(isParkingTimeExpired(car,meter) == true){
  4.           ParkingTicket ticket = new ParkingTicket(officerName,officerBadgeNumber,car.getLicensePlateNumber(),calculateFine(car,meter));
  5.           
  6.           ticketList.add(ticket);
  7.           ticket.displayDetails();
  8.     }

Now in my main driver class, I have to created an officer object but since I had to make the method void to not return anything I am getting an error saying void cannot be converted to ParkingTicket, if i take away myCar1,myMeter1 from the parentheses, I get an error telling me there's arguments required ParkedCar , ParkingMeter. How can I make it so I don't get an error and the officer object created can issue a parking ticket?

  1.  public class Driver
  2. {
  3.     main method
  4.     public static void main(String [] args){
  5.             
  6. ParkedCar myCar1 = new ParkedCar("Fred","toyota",2013,"Z1234",25);
  7.     myCar1.displayDetails();
  8.     
  9.     ParkingMeter myMeter1 = new ParkingMeter("SYDNEY",true,0.15,70); 
  10.     myMeter1.displayDetails();
  11.     
  12.     
  13.     PoliceOfficer officer1 = new PoliceOfficer("John doe","DMX1234"); 
  14.     ParkingTicket ticket = officer1.issueParkingTicket(myCar1,myMeter1);

This is the source of my error ParkingTicket ticket = officer1.issueParkingTicket(myCar1,myMeter1);

答案1

得分: 2

你只需在主函数中删除以下部分：

  1. ParkingTicket ticket =

由于在函数中已创建了停车券，因此在调用函数时无需创建新的停车券。

英文:

You can just remove the part that says:

  1. ParkingTicket ticket =

in your main method.

Since the ticket is created in the function there is no need to create a new ticket when you call the function.

答案2

得分: 1

在ParkedCar中添加一个数组或列表，用于跟踪该车辆的所有罚单。

  1. public void issueParkingTicket(ParkedCar car, ParkingMeter meter)
  2. {
  3.    if(isParkingTimeExpired(car, meter)){
  4.       ParkingTicket ticket = new ParkingTicket(officerName, officerBadgeNumber, car.getLicensePlateNumber(), calculateFine(car, meter));
  5.       car.tickets.add(ticket);
  6.    }
  7. }

然后在您的主类中，您可以访问任何车辆对象的所有罚单。

  1. public static void main(String[] args)
  2. {
  3.   ParkedCar car = new ParkedCar(/*params*/);
  4.   Officer officer1 = new Officer(/*params*/);
  5.   officer1.issueTicket(/*params*/);
  7.   // 在ParkedCar类中创建一个获取罚单的方法
  8.   car.getTickets();
  9. }
英文:

Add an array or List to ParkedCar that keeps track of all the tickets for that vehicle.

  1. public void issueParkingTicket(ParkedCar car, ParikingMeter meter)
  2. {
  3.    if(isParkingTimeExpired(car,meter) == true){
  4.       ParkingTicket ticket = new ParkingTicket(officerName,officerBadgeNumber,car.getLicensePlateNumber(),calculateFine(car,meter));
  5.   car.tickets.add(theTicket);

}

then in your main class you can access every ticket for any car object.

  1. public static void main(String [] args)
  2. {
  3.   ParkedCar car = new ParkedCar(/*params*/);
  4.   Officer officer1 = new Officer(/*params*/);
  5.   officer1.issueTicket(/*params*/);
  7.   //make a getter for the tickets in the ParkedCar class
  8.   car.getTickets();
  9. }

答案3

得分: 0

你可以传入一张票据，并在issueParkingTicket方法内部操作该票据。

  1. ParkingTicket ticket = new ParkingTicket();
  2. officer1.issueParkingTicket(myCar1, myMeter1, ticket); 
  3. ticket.displayDetails();
英文:

You can pass in a ticket, and manipulate the ticket inside the issueParkingTicket method.

  1. ParkingTicket ticket = new ParkingTicket();
  2. officer1.issueParkingTicket(myCar1,myMeter1,ticket); 
  3. ticket.displayDetails();

huangapple
  • 本文由 发表于 2020年4月4日 10:39:21
  • 转载请务必保留本文链接：https://go.coder-hub.com/61023147.html
  • arraylist
  • java
  • oop
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