How to add setter and getter to member variables of a Parcelable class

Question

Below is a class that I'm currently working on

@Parcelize
class Time(var hour:Int, var minute:Int):Comparable<Time>,Parcelable

I want to add a setter to member variables hour and minute so that they would stay in time format. And the class has to be passed through intent, so it implements Parcelable. But it says that a Parcelable class should have a primary constructor so I'm having problem with adding setters. Can anyone please tell me why and a solution? Thank you.

I'm not familiar with kotlin, but what exactly hinders you writing custom methods? — Rafael T, Nov 27 '18 at 12:37

nyarian · Answer 1 · 2018-11-27T12:51:37.737

2

Kotlin's properties are already shipped with getters and setters. Every time you say time.hour = 5 or val currentTime = time.hour - corresponding setter or getter is invoked.

The problem here is not with constructor, but with CREATOR that parcelable requires.

The complete example would look like this:

class Time(var hour: Int, var minute: Int) : Comparable<Time>, Parcelable {

    override fun writeToParcel(dest: Parcel?, flags: Int) {
        dest!!.writeInt(hour)
        dest.writeInt(minute)
    }

    override fun describeContents(): Int = 0

    override fun compareTo(other: Time): Int {
        // your comparsion logic
    }

    companion object CREATOR : Parcelable.Creator<Time> {
        override fun createFromParcel(parcel: Parcel): Time {
            return Time(parcel.readInt(), parcel.readInt())
        }

        override fun newArray(size: Int): Array<Time?> {
            return arrayOfNulls(size)
        }
    }
}

edited Nov 27 '18 at 12:51

answered Nov 27 '18 at 12:45

nyarian

4,085
1
19
51

I'm currently using the @Parcelize decorator. Should I override CREATOR? – Inyoung Kim 김인영 Nov 27 '18 at 12:51
If you use `@Parcelize`, then making this class a data class (`data class Time(var hour: Int, var minute: Int) : Comparable, Parcelable`) would be enough. – nyarian Nov 27 '18 at 12:53
How do you modify setter? – Inyoung Kim 김인영 Nov 27 '18 at 12:54
You mean overriding default setter with custom implementation? Here's how you can do it: https://stackoverflow.com/questions/38492103/override-getter-for-kotlin-data-class – nyarian Nov 27 '18 at 12:58
Yes. I have to override default setter. – Inyoung Kim 김인영 Nov 27 '18 at 13:00
1

It is not recommended to contain processing logic inside data classes, so I would recommend either to wrap `Time` data class instance with another object that knows how to parse, or making `Time` not data class and implement mentioned methods yourself. – nyarian Nov 27 '18 at 13:01
I guess wrapping it would be the best solution. Thanks for your help. – Inyoung Kim 김인영 Nov 27 '18 at 13:04

How to add setter and getter to member variables of a Parcelable class

1 Answers1