I've followed some tutorials for creating a Bluetooth scanning app. Currently, I can scan for nearby devices and their name and address are displayed in a ListView. I wan't to be able to add their UUID just below this but I can't work out how to achieve this.
MainActivity.java
public void discoverDevices(View view) {
if(mBluetoothAdapter.isDiscovering()){
// When discovering devices, you want to cancel the discovery and start it up again
mBluetoothAdapter.cancelDiscovery();
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, discoverDevicesIntent);
}
// If the phone isn't discovering, then we start the discovery.
if(!mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, discoverDevicesIntent);
}
}
// This creates a BroadcastReceiver for listening devices that aren't already paired.
//This is then executed by using the listDevices() method.
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
Log.d(TAG, "onReceive: ACTION FOUND.");
if (action.equals(BluetoothDevice.ACTION_FOUND)){
BluetoothDevice device = intent.getParcelableExtra (BluetoothDevice.EXTRA_DEVICE);
mBTDevices.add(device);
Log.d(TAG, "Device: " + device.getName() + ": " + device.getAddress());
mDeviceList = new DeviceList(context, R.layout.list_devices_view, mBTDevices);
listView.setAdapter(mDeviceList);
}
}
};
DeviceList.java
public class DeviceList extends ArrayAdapter<BluetoothDevice> {
private LayoutInflater mLayoutInflater;
private ArrayList<BluetoothDevice> mDevices;
private int mViewResourceId;
public DeviceList(Context context, int tvResourceId, ArrayList<BluetoothDevice> devices){
super(context, tvResourceId,devices);
this.mDevices = devices;
mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mViewResourceId = tvResourceId;
}
public View getView(int position, View convertView, ViewGroup parent) {
convertView = mLayoutInflater.inflate(mViewResourceId, null);
BluetoothDevice device = mDevices.get(position);
if (device != null) {
TextView deviceName = (TextView) convertView.findViewById(R.id.deviceName);
TextView deviceAdress = (TextView) convertView.findViewById(R.id.deviceAddress);
TextView deviceUUID = (TextView) convertView.findViewById(R.id.deviceUUID);
if (deviceName != null) {
deviceName.setText("Name: " +device.getName());
}
if (deviceAdress != null) {
deviceAdress.setText("MAC: " +device.getAddress());
}
if (deviceUUID != null) {
ParcelUuid[] uuids = device.getUuids();
}
}
return convertView;
}
}
list_devices_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/deviceName"
android:textSize="20dp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/deviceAddress"
android:textSize="20dp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/deviceUUID"
android:textSize="20dp"/>
Logcat data
FATAL EXCEPTION: main
Process: com.example.toby.btapp, PID: 21557
java.lang.NullPointerException: Attempt to get length of null array
at com.example.toby.btapp.DeviceList.getView(DeviceList.java:47)
at android.widget.AbsListView.obtainView(AbsListView.java:2929)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1305)
at android.widget.ListView.onMeasure(ListView.java:1212)
at android.view.View.measure(View.java:20166)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:716)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:462)
at android.view.View.measure(View.java:20166)
at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:927)
at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:966)
at android.view.View.measure(View.java:20166)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:20166)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:393)
at android.view.View.measure(View.java:20166)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:20166)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20166)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:3143)
at android.view.View.measure(View.java:20166)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2644)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1599)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1891)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1487)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7450)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:920)
at android.view.Choreographer.doCallbacks(Choreographer.java:695)
at android.view.Choreographer.doFrame(Choreographer.java:631)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:906)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
