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android – Safe Args: use list of parcelables

Posted by: admin May 14, 2020 Leave a comment

Questions:

I am using the Safe Args plugin with the new Navigation components for my Android project. Now I have an argument that is an array list of parcelables, is there a way to use this with the Safe Args Plugin?

Something like app:argType=ParcelableArray. This should be possible since there are bundle methods like putParcelableArrayList().

How to&Answers:

Currently i don’t think there is a simple way to use list of parcelables with safe args,
But i have found some “hack” to make this work.
For example, i have object ‘User’ and it parcelable, i am declaring a new parcelable object ‘Users’ that extending ArrayList().

@Parcelize
data class User(var name: String, val age: Int): Parcelable

@Parcelize
class Users: ArrayList<User>(), Parcelable

Now i can set ‘Users’ as argument in navigation

<argument
      android:name="users"
      app:argType="com.navigation.test.Users"/>

And passing array list of parcelables between destinations:

 val user=User("Alex", 36)
 val users= Users()
 users.add(user)
 val action=MainFragmentDirections.actionMainFragmentToSecondFragment(users)
 NavHostFragment.findNavController([email protected]).navigate(action)

And to retrieve them on other destination:

val users=SecondFragmentArgs.fromBundle(arguments).users
val user=users[0]
txtViewName.text=user.name
txtViewAge.text="${user.age}"

Update:

Support to list of objects coming in alpha8:
https://issuetracker.google.com/issues/111487504

Answer:

Yes, since version 1.0.0-alpha08 you can now pass arrays of parcelable objects like this:

<argument
  android:name="users"
  app:argType="com.navigation.test.User[]"/>

For passing arrays of primitive types use for e.g. app:argType="integer[]"

Answer:

An improvement to @LaVepe suggestion: as for Android Studio 3.4.2 you can pass Parcelable array with in-built feature of navigation editor by specifying Arguments for chosen destination. Just check ‘Array’ option after choosing your custom Parcelable class which should not be wrapped in any collection beforehand:

Example

EDIT
Here how it looks in xml:

<argument
        android:name="items"
        app:argType="com.company.domain.Item[]" />

In your Fragment/Activity code you might strictly pass a typed array of model Parcelable items. If you have non-array collection and write in Kotlin, it may be achieved with (if you have list beforehand) list.toTypedArray().