Question 125480 in Android Studio Question posted in
The official documentation can be found here.

Android Studio – Popup dialog spinner with bondedDevices is null

When trying to make a popup dialog with paired bluetooth devices in a spinner, my app crashes upon opening. See this code for the xml layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp">
    
    <Spinner
        android:id="@+id/spinner_devices"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/bConnectBtn"
        android:text="CONNECT"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

In the code below here, I call a function that checks for bonded devices and then puts it in the spinner:

private fun onBluetoothEnabled() {
    val bondedDevices = bluetoothAdapter?.bondedDevices
    if (bondedDevices != null) {
        val bondedAdapter = ArrayAdapter(this, android.R.layout.simple_spinner_item, bondedDevices.map { it.name })
        bondedAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
        spinner_devices.adapter = bondedAdapter

        bConnectBtn.setOnClickListener {
            val device = bondedDevices.toList()[spinner_devices.selectedItemPosition]
            setupClient(device)
        }
    }
}

Here I show the dialog:

val bluetoothView = layoutInflater.inflate(R.layout.bluetoothdialog, null)
val bluetoothDialog = AlertDialog.Builder(this@MainActivity)

bluetoothDialog.setTitle("Paired Devices")
bluetoothDialog.setView(bluetoothView)
bluetoothDialog.setCancelable(false)
bluetoothDialog.setNeutralButton("TEMP CLOSE") { _, _ -> }

bluetoothDialog.show()

Some extra details about this, this works just fine when the spinner is in the main activity xml, but when I put the spinner in a popup dialog xml file, it crashes upon start. When I add ? or !! to spinner_devices?.adapter it works but doesn’t fill the spinner with the bonded devices which makes sense because it allows null now.

When I debug my code, I can see that the bondedApapter gets filled with paired bluetooth devices, but when it gets to the spinner_devices.adapter it is null. Any guesses on what I am doing wrong?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    For those wondering. I was able to fix it and made it a bit more usefull by being able to click on a bluetooth device and make it connect. See code below for full code:

    private fun showPairedDevicesPopup() {
    val bluetoothAdapter = BluetoothAdapter.getDefaultAdapter()
    val pairedDevices: Set<BluetoothDevice> = bluetoothAdapter.bondedDevices

    // Create a list of device names
    val deviceNames = ArrayList<String>()
    pairedDevices.forEach { deviceNames.add(it.name) }

    // Create an array adapter to display the list of device names
    val adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, deviceNames)

    // Build the alert dialog
    val builder = AlertDialog.Builder(this)
    builder.setTitle("Paired Devices")
    builder.setCancelable(false)
    builder.setAdapter(adapter) { _, which ->
        // Get the selected device
        val selectedDevice = pairedDevices.elementAt(which)

        // Attempt to connect to the selected device
        val socket: BluetoothSocket?
        try {
            socket = selectedDevice.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"))
            socket.connect()
        } catch (e: IOException) {
            // Failed to connect to the device
            e.printStackTrace()
        }
    }
    builder.setNegativeButton("Cancel") { dialog, _ ->
        dialog.dismiss()
    }

    // Show the alert dialog
    val dialog = builder.create()

    dialog.show()
}

  2. 0

    There is some object initialization when you tries to bind adapter from AlertDialog. Checkout the below code that is working fine.

    val bluetoothView = layoutInflater.inflate(R.layout.bluetoothdialog, null)
val bluetoothDialog = AlertDialog.Builder(this@MainActivity)
bluetoothDialog.setTitle("Paired Devices")
bluetoothDialog.setView(bluetoothView)
bluetoothDialog.setCancelable(false)
bluetoothDialog.setNeutralButton("TEMP CLOSE") { _, _ ->}
bluetoothDialog.show()

    **//get views from inflated layout

    val spinnerDevices = bluetoothView.findViewById(R.id.spinner_devices)

    val bConnectBtn = bluetoothView.findViewById(R.id.bConnectBtn)**

     //bind adapter
val bondedAdapter = ArrayAdapter(this, android.R.layout.simple_spinner_item, bondedDevices.map { it.name })
               bondedAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
spinnerDevices.adapter = bondedAdapter

bConnectBtn.setOnClickListener {
val device = bondedDevices.toList()[spinnerDevices.selectedItemPosition]
Toast.makeText(this@MainActivity,"Connection to:${device.name}",Toast.LENGTH_SHORT).show()

    }

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search