Basic Java GUI Application - Array Searching

I am currently working on a application for a car park system. It uses GUI created by myself and holds 15 parking spaces. The user has the option to add, delete or search for a specific car. When the user adds a new car, details of the car are entered, the cars registration number (saved as a string), and the user had to check one raido button if the car is expensive, large or normal.

Once this information is entered a new instance of a vehicle will be created and the bay the car is allocated to turns green and stored in one of three arrays(expensive, normal or large). I also have a fourth array for creating the parking spaces.Each array can only hold 5 vehicles apart from the fourth which can hold all 15. When searching for a vehicle the user enters the registration of the vehicle they want to find, but I have to search through all three arrays to find it, and if it does not exist showing a message saying so.These are my three arrays

public static ParkingBay[] regularBays = new ParkingBay[5];
public static ParkingBay[] largeBays = new ParkingBay[5];
public static ParkingBay[] expensiveBays = new ParkingBay[5];

String Registration; - saves registration entered from add form
String RegistrationNumber; - saves registration number from search form

I need to search to see if RegistrationNumber is in either of the three arrays if not show a message saying otherwise