Null-Infested Address

StephensAddress.java

public class Address {

	private final String addressLine;  // never null
	private final String city;         // never null
	private final String postcode;     // optional, thus may be null

	// constructor ensures non-null fields really are non-null
	// optional field can just be stored directly, as null means optional
	public Address(String addressLine, String city, String postcode) {
		this.addressLine = Preconditions.chckNotNull(addressLine);
		this.city = Preconditions.chckNotNull(city);
		this.postcode = postcode;
	}

	// normal getters
	public String getAddressLine() {
		return addressLine;
	}

	public String getCity() {
		return city;
	}

	// special getter for optional field
	public Optional<String> getPostcode() {
		return Optional.ofNullable(postcode);
	}

	// return optional instead of null for business logic methods that may not find a result
	public static Optional<Address> findAddress(String userInput) {
		return... // find the address, returning Optional.empty() if not found
	}

}