How to make LocalDate and LocalTime parcelable?

Question

I am new to android, and making a doctor's appointment managing android app using ThreeTenABP's (so it's compatible with more devices) LocalDate and LocalTime, which I need to make parcelable.

I have the parcelable complex class Appointment, which has instances of LocalDate and LocalTime as attributes; classes I don't think are parcelable by default.

I don't want to change the logic to work with different classes, or primitives even; since these classes are used widely throughout the app. Naturally, these attributes are not put in the Appointment(Parcel in) method automatically, and I don't know how to include them, or if it's even possible.

Performance is very important, so I'm not considering Serializable as an option either.

This is the Appointment class (also, I made sure to make all other custom objects parcelable):

public class Appointment implements Parcelable{

    private Patient patient;
    private LocalDate date;
    private LocalTime time;
    private Doctor doctor;
    private Prescription prescription;

    public Appointment(Patient patient, LocalDate date, LocalTime time, Doctor doctor, Prescription prescription) {

        this.patient = patient
        this.date = date;
        this.time = time;
        this.doctor = doctor;
        this.prescription = prescription;
    }

    protected Appointment(Parcel in) {
        patient = in.readParcelable(Patient.class.getClassLoader());
        doctor = in.readParcelable(Doctor.class.getClassLoader());
        prescription = in.readParcelable(Prescription.class.getClassLoader());
    }

    public static final Creator<Appointment> CREATOR = new Creator<Appointment>() {

        @Override
        public Appointment createFromParcel(Parcel in) {
            return new Appointment(in);
        }

        @Override
        public Appointment[] newArray(int size) {
            return new Appointment[size];
        }
    };

    //Class methods

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeParcelable(patient, flags);
        dest.writeParcelable(doctor, flags);
        dest.writeParcelable(prescription, flags);
    }
}

I already tried adding date and time to Appointment(Parcel in) and writeToParcel() just like the other attributes, but it says parameters are the wrong type:

Wrong 1st argument type. Found: 'org.threeten.bp.LocalDate', required: 'android.os.Parcelable'

I'm not getting any error messages if I leave it withput date and time, but the app crashes when it gets to the intent.putExtra() method to pass the object to the corresponding activity.

Please, help

"Performance is very important, so I'm not considering Serializable as an option either" Did you actually measure whether it has a significant impact in your code? Writing/reading as Serializable would be the easy way here. — laalto
I'm gonna be honest, I hadn't tried Serializable and it works. Thank you! I would like to change it to parcelable in the future if possible, though. — Marianne Rojas
You only need Serializable with these fields in Parcel, not all over the place — laalto

Johnz Johnz · Accepted Answer · 2020-03-29T19:17:36

@Override
protected Appointment(Parcel in) {
    // Read objects
    date = (LocalDate) in.readSerializable();
    time = (LocalTime) in.readSerializable();
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    // Write objects 
    dest.writeSerializable(date);
    dest.writeSerializable(time);
}

This post here explains the performance details so well. I don't have to repeat them here.

A more performant approach would be converting your date objects to long and while writing to a parcel and converting them back to the relevant date objects when reading from the parcel.

How to make LocalDate and LocalTime parcelable?

1 Answers