I am just trying to set up a spinner configured as a dropdown menu, but I can't even test my app to see if it works because every time I run it, it immediately crashes. I know that my issue is related to a null object reference at line 21 in my MainActivity.kt file. Here is the problem code: val spinner: Spinner = findViewById<Spinner>(R.id.locations) The id of the spinner is locations, so I'm not sure why this is coming back as a null value. Here is also the full code for the file:
import android.app.Activity
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Spinner
import android.widget.ArrayAdapter
import android.widget.AdapterView
private var userLocation: Any = ""
private var userDestination: Any = ""
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
val spinner: Spinner = findViewById<Spinner>(R.id.locations)
val locationsAdapter: ArrayAdapter<CharSequence> = ArrayAdapter.createFromResource(
this,
R.array.rooms,
android.R.layout.simple_spinner_item
).also { adapter ->
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
spinner.adapter = adapter
}
}
class SpinnerActivity : Activity(), AdapterView.OnItemSelectedListener {
override fun onItemSelected(parent: AdapterView<*>, view: View?, pos: Int, id:Long) {
userLocation = parent.getItemAtPosition(pos)
val spinner: Spinner = findViewById(R.id.locations)
spinner.onItemSelectedListener = this
}
override fun onNothingSelected(parent: AdapterView<*>) = Unit
}
Declare spinner global for MainActivity:
private lateinit var spinner: Spinner
On the method onCreate initialise the spinner and set its adapter, I would recommend you to set the array adapter as follows:
spinner = findViewById<Spinner>(R.id.locations)
spinner.adapter = ArrayAdapter(this, R.layout.drop_down_generic_item, resources.getStringArray(R.array.rooms))
I don't really understand the SpinnerActivity you showed in the question, sorry. But in MainActivity you can set the spinner.onItemSelectedLister() as follows:
spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onItemSelected(adapterView: AdapterView<*>?, view: View?, position: Int, p3: Long) {
val selectedRoom = adapterView?.getItemAtPosition(position)
}
override fun onNothingSelected(p0: AdapterView<*>?) {
}
}
I don't want to confuse you, but have a look at a TextInputLayout with an AutoCompleteTextView, just as a hint. :D
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments