I want to use get set method in field of data class kotlin

Question

data class Thermostat(
    // ... other properties

    @SerializedName("units")
    private var _units: String?, // Fahrenheit,

    // ... other properties
) : Serializable {
    var units: String? = null
        get() = _units
        set(value) {
            MyApplication.temperatureServerIsCelsius = (!value?.equals("Fahrenheit")!!)
            _units = value
        }
}

When _units receives the value, I want to assign that value to units (inside the model class) but, it isn't doing so here.

Actually, I want a variable in MyApplication modified in accordance with the value of the _units field.

How can I achieve that? Is there any way we can use get set method directly in field? like this(I know these is not correct but anything like these possible?)

data class Thermostat(
    // ... other properties

    @SerializedName("units")
    private var _units: String?
       get() = _units
       set(value) {
                MyApplication.temperatureServerIsCelsius = 
                (!value?.equals("Fahrenheit")!!)
            }
    )

Any solution or any other way to do this type thing?.

Meet Prajapati · Accepted Answer · 2023-11-29 10:06:39Z

0

You need to remove the default initializer from the unit.

data class Thermostat(
    private var _units: String?, // Fahrenheit,
) {
    var units: String?
        get() = _units
        set(value) {
            _units = value
        }
}

Usage :

 val s = Thermostat(null)
    s.units = "Fahrenheit"
    println(s)

Output :

Thermostat(_units=Fahrenheit)

answered Nov 29, 2023 at 10:06

Meet Prajapati

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10 Comments

Mohammad Taqi Over a year ago

thx! but still not working. I want assigning value in set block to a variable in application class but it is not assigned >>>>set(value) { MyApplications.testVariable= _units.toString() _units = value }

Mohammad Taqi Over a year ago

Actually I want to check the _units value and apply condition on that basis in that set block inside the data class.

Meet Prajapati Over a year ago

I have made a demo here, take a look pl.kotl.in/haAhc5rmu

Mohammad Taqi Over a year ago

Thanks for your effort. But in Android studio it tell this with red line "value-parameter val get: [Error type: Missed a type for a value parameter get]"

Meet Prajapati Over a year ago

There is no val in the link I have just sent. It is working properly in android studio as well.

|

Steyrix · Accepted Answer · 2023-11-29 10:36:52Z

0

I suggest to avoid the idea of setting fields after creating instance of the data class. The point of data classes is to consistently contain data, and immutable data is usually safer than mutable.

I don't think that there is a point to store private data in a data class either (at least in your case), because data classes should not have logic. Your set method has side-effect, which is not a good practice. You should avoid side-logic in setters, do it separately. Nobody expects set method to do something else besides setting the value.

The easiest way to have an instance of the data class with up-to-date data is to create one in place.

answered Nov 29, 2023 at 10:36

Steyrix

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3 Comments

Mohammad Taqi Over a year ago

👍👍Okay. I was just doing this as I am getting the value in particular units and need to convert all that in another unit.

Steyrix Over a year ago

@MohammadTaqi you should do this outside of the data class

Mohammad Taqi Over a year ago

Yes. I believe I only need to accomplish that.

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