Passing and retrieving MutableList or ArrayList from Activity A to B

Question

I need to pass this:

private lateinit var memes: MutableList<Memes>

which has this model:

class Memes (
    @SerializedName("id") var id: Long,
    @SerializedName("title") var title: String
)

from activity a to b.

I've altready seen couple "solutions" and none of them works!

This is the last that I've tried:

    val extras = Bundle()
    val memesArrayList = ArrayList(memes)
    val i = Intent(context, GalleryShow::class.java)
    i.putExtras(extras)
    i.putStringArrayListExtra("list", memesArrayList)
    (context as Activity).startActivityForResult(i, 777)

However, I get Type mismatch: inferred type is ArrayList<Memes!> but ArrayList<String!>? was expected on memesArrayList.

EDIT:

This is my latest attempt now:

In activity A inside recyclerview item:

val extras = Bundle()

extras.putString("gal", "animals")
extras.putString("query", "")

val i = Intent(context, GalleryShow::class.java)
i.putExtra("list", memes.toTypedArray())
i.putExtras(extras)
(context as Activity).startActivityForResult(i, 777)

and this is inside activity B:

private lateinit var memes: MutableList<Memes>


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_gallery_show)

    memes = (this?.intent?.extras?.get("list") as? Array<Memes>)?.asList()!!.toMutableList()
}

I would say that probably, since the objects are so simple, you can just serialize it to json and deserialize it (or try with `putSerializableExtra `) — Alberto Sinigaglia, Jun 15 '21 at 15:54
I tried that too but there is no god damn example how to do that properly! All those array types are the dumbest shit in the history of programming! There should be just one damn array type not 10000 — Eduard Unruh, Jun 15 '21 at 15:55
(in the worst case, you can create a singleton between the 2 activity, but if you can avoid it, avoid it) — Alberto Sinigaglia, Jun 15 '21 at 15:56
I tried that too, getting Unresolved reference: putSerializableExtra — Eduard Unruh, Jun 15 '21 at 15:59
please have a look at this https://stackoverflow.com/questions/5374546/passing-arraylist-through-intent — Alberto Sinigaglia, Jun 15 '21 at 16:00
I've seen that too, only works with plain string lists. This one seems to work sending: val memesArrayList = ArrayList(memes) extras.putSerializable("crap", memesArrayList) but how to reverse all that converting in activity B? — Eduard Unruh, Jun 15 '21 at 16:06

Tenfour04 · Accepted Answer · 2021-06-15T19:49:06.583

You can use simply intent.putExtra instead of worrying about which variant like put_____Extra to use.

When extracting the value, you can use intent.extras to get the Bundle and then you can use get() on the Bundle and cast to the appropriate type. This is easier than trying to figure out which intent.get____Extra function to use to extract it, since you will have to cast it anyway.

The below code works whether your data class is Serializeable or Parcelable. You don't need to use arrays, because ArrayLists themselves are Serializeable, but you do need to convert from MutableList to ArrayList.

// Packing and sending the data:
val i = Intent(context, GalleryShow::class.java)
i.putExtra("list", ArrayList(memes)) // where memes is your MutableList<Meme> property
startActivityForResult(i, 777)

// Unpacking the data in the other activity:
memes = intent.extras?.get("list") as MutableList<Meme>

Passing and retrieving MutableList or ArrayList from Activity A to B

1 Answers1