坚持在 Java 中返回 ArrayList

Question

Edit, so I modified my method a bit like this:

import java.util.ArrayList

public ArrayList<ParkingTicket> getTicketArrayByLicenseNumber(String licensePlate){
        ArrayList<ParkingTicket> tickets = new ArrayList();
        for(ParkingTicket list: ticketList){
            String ticket = list.getCarLicensePlateNumber();
            if(ticket != null && ticket.equalsIgnoreCase(licensePlate)){
                tickets.add(list);
            }
        }
        return tickets;
    }

I think this will work. However when I test it using a test class, it gives me this error:

testMethodGetTicketArrayByLicenseNumb
---
java.lang.AssertionError: PoliceOfficer.getTicketArrayByLicenseNumber must be return "[LParkingTicket;"
    at org.junit.Assert.fail(Assert.java:88)
    at PoliceOfficerTest.testMethod(PoliceOfficerTest.java:296)
    at PoliceOfficerTest.testMethodGetTicketArrayByLicenseNumb(PoliceOfficerTest.java:70)

Am I missing something here??

As per my assignment I need to create a method that takes a car licence Plate (a string) and return an array of any parking tickets object that is issued to the car.

The parking ticket is part of an ArrayList.

private ArrayList<ParkingTicket> ticketList;

public ParkingTicket getTicketArrayByLicenseNumber(String licensePlate){
        
        for(ParkingTicket list: ticketList){
            String ticket = list.getCarLicensePlateNumber();
            if(ticket != null && ticket.equalsIgnoreCase(licensePlate)){
                return list;
            }
        }
        return null;
    }

Struck on what to do now as the code doesn't seem to return what I want...

Answer 1

You are returning object and not a list of objects.

If you are familiar with Java 8 streams, the problem can be solved as below:

private List<ParkingTicket> ticketList;

private List<ParkingTicket> getTicketArrayByLicenseNumber(String licensePlate) {
    return ticketList.stream()
            .filter(parkingTicket -> isLicensePlateNumberMatching(licensePlate, parkingTicket.getCarLicensePlateNumber()))
            .collect(Collectors.toList());
}

private boolean isLicensePlateNumberMatching(String licensePlate, String carLicensePlateNumber) {
    return carLicensePlateNumber != null && carLicensePlateNumber.equalsIgnoreCase(licensePlate);
}

For solution without using streams you should proceed with:

private List<ParkingTicket> getTicketArrayByLicenseNumber(String licensePlate) {
    List<ParkingTicket> ticketsMatching = new ArrayList<>();
    for (ParkingTicket parkingTicket : ticketList) {
        if(isLicensePlateNumberMatching(licensePlate, parkingTicket.getCarLicensePlateNumber())){
            ticketsMatching.add(parkingTicket);
        }
    }
    return ticketsMatching;
}