Passing An Object Instance Between Two Activities In Kotlin

I'm wondering if someone could help me to fix this error with Intent? I have 2 activities to connect between the: The first activity for Grid View 'MainActivity.kt', second for L

Solution 1:

Create an IntDef like:

@Retention(SOURCE)
@IntDef({ADAPTER_MODE_1, ADAPTER_MODE_2, ADAPTER_MODE_3})
public @interface AdapterMode {}
public static final int ADAPTER_MODE_1 = 0;
public static final int ADAPTER_MODE_2 = 1;
public static final int ADAPTER_MODE_3 = 2;
//...

and add the int to the bundle. For Kotlin you have to use a companion object to define the variables like

class FirstActivity {
    companion object { 
         val ADAPTER_MODE1 = 0
         val ADAPTER_MODE2 = 1
         val ADAPTER_MODE3 = 2
         //...
    }
}

So you can pass unlimited adapter cases to your 2nd activity

EDIT: Kotlin doesn't support @IntDef so you should use an enum for that:

enum class AdapterType {
    ADAPTER_TYPE_1,
    ADAPTER_TYPE_2,
    ADAPTER_TYPE_3;

    companion object {
        fun fromOrdinal(ordinal: Int): AdapterType? {
            return AdapterType.values().firstOrNull { it.ordinal == ordinal }
        }
    }
}

Then use it like:

class FirstActivity : AppCompatActivity() {

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

        val intent = Intent(this, SecondActivity::class.java)
        intent.putExtra(SecondActivity.EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_2.ordinal)
    }
}

And retrieve it like:

class SecondActivity : AppCompatActivity() {
    companion object {
        val EXTRA_ADAPTER_MODE = "extra_adapter_mode"
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        //...
        val adapterTypeOrdinal = intent?.getIntExtra(EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_1.ordinal)
        val adapterType = adapterTypeOrdinal?.let { AdapterType.fromOrdinal(it) }

        // do something with it
    }
}

Solution 2:

You can not pass Adapters between Activities. At least in a clean way, recommended by Google. Adapters implement neither Parcelable nor Serializable interface. So general rule, as Nino Handler pointed out - use Intent to send data (not Adapters itself) which should be used to create Adapter.