How to pass object between activities in android using Kotlin?

We can pass primitive data (Int, Float, Double, String etc.) by using Intent.

// send data
val intent = Intent(context, NextActivity::class.java)
intent.putExtra("name", "Arun Aditya")
context.startActivity(intent)

// receive data
val name = intent.getStringExtra("name")        

You can pass an object between activities in Android using Parcelable or Serializable interface.

1. Serializable

• Serializable is a markable interface or we can call as an empty interface. It doesn’t have any pre- implemented method.
• Convert an object to byte stream.
• Serializable is standard java interface.
• Creation and passing data are very easy but it is slow process as compared to Parcelable.
• Serializable is a good choice to use when you want to store the state of an object to a file, a database or over a network.

Follow these steps to use Serializable.

Step 1-> make sure your object class implement the serializable

data class DummyObject(val name: String): Serializable        

Step 2-> In the first activity, put the object in an Intent and start the second activity.

val intent = Intent(this, NextActivity::class.java)
val dummyObject = DummyObject("Arun Aditya")
intent.putExtra("object", dummyobject)
startActivity(intent)        

Step 3 -> In Second Activity, get the object from the intent.

val object = intent.getSerializableExtra("object") as DummyObject        

2. Parcelable

• More efficient and faster.
• Directly marshals and unmarshals the data to and from memory.
• Parclable is specific to Android and is the recommended method.

Follow these steps to use Parcelable.

Step 1-> Make your object class implement the Parcelable interface.

data class MovieData(
    val sr_no: Int = 0,
    val name: String = "",
    val generic: String = "",
    val year: String = "",
    val length: String = "",
    val director: String = "",
    val decp: String = "",
    val url: String = ""
    ): Parcelable{
    constructor(parcel: Parcel) : this(
        parcel.readInt(),
        parcel.readString()!!,
        parcel.readString()!!,
        parcel.readString()!!,
        parcel.readString()!!,
        parcel.readString()!!,
        parcel.readString()!!,
        parcel.readString()!!
    ) {
    }

    override fun writeToParcel(parcel: Parcel, flags: Int) {
        parcel.writeInt(sr_no)
        parcel.writeString(name)
        parcel.writeString(generic)
        parcel.writeString(year)
        parcel.writeString(length)
        parcel.writeString(director)
        parcel.writeString(decp)
        parcel.writeString(url)
    }

    override fun describeContents(): Int {
        return 0
    }

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

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

}        

Step 2-> In the first activity, put the object in an Intent and start the second activity.

val intent = Intent(context, DetailsActivity::class.java)
list = setData.movieList()
intent.putExtra("movie", list[0])
startActivity(intent)        

Step 3 -> In Second Activity, get the object from the intent.

val movie = intent.getParcelableExtra<MovieData>("movie")        

If you need to transfer data between activities in Android, use Parcelable for faster and more efficient data transfer, while if you need to store data in a more general way, you can use Serializable.

#ArunAditya #Android #AndroidApplication developer