Develop Reference

Can't resolve symbol R

I've been working on this bluetooth data transfer project for a while and now while I'm done with it, I keep getting this annoying error nonStop next to another error which is
Error:(41, 35) No resource found that matches the given name (at 'layout_toRightOf' with value '#id/edttxt').
Any ideas where's the problem?
activity main
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:background="#drawable/mybg"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.cy.el.bluetoothtransfer.MainActivity">
<Button
android:text="ON/OFF"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_alignParentTop="true"
android:background="#drawable/selector2"
android:layout_alignParentRight="true"
android:id="#+id/btnONOFF"/>
<Button
android:text="Enable Discoverable"
android:layout_width="189dp"
android:layout_height="50dp"
android:background="#drawable/selector"
android:id="#+id/btnDiscoverable_on_off"
android:onClick="btnEnableDisable_Discoverable"
android:layout_alignParentTop="true" />
<Button
android:layout_width="95dp"
android:layout_height="50dp"
android:id="#+id/btnFindUnpairedDevices"
android:text="Discover"
android:layout_toRightOf="#id/edttxt"
android:layout_marginLeft="50dp"
android:layout_above="#id/edttxt"
android:layout_marginTop="40dp"
android:background="#drawable/selector"
android:onClick="btnDiscover"/>
<ListView
android:layout_marginTop="120dp"
android:layout_width="match_parent"
android:layout_height="200dp"
android:id="#+id/lvNewDevices"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/lvNewDevices"
android:layout_marginTop="30dp"
android:layout_alignParentLeft="true"
android:textSize="20dp"
android:layout_marginLeft="30dp"
android:textColor="#fffffe"
android:id="#+id/information" />
<EditText
android:layout_width="200dp"
android:layout_height="100dp"
android:layout_below="#id/information"
android:hint=" Type here : "
android:textColor="#fffffe"
android:background="#fafafa"
android:layout_marginTop="50dp"
android:id="#+id/edttxt"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/information"
android:layout_toRightOf="#id/edttxt"
android:text="Send"
android:background="#drawable/selector2"
android:layout_marginTop="50dp"
android:layout_marginLeft="50dp"
android:id="#+id/sendBtn"/>
<Button
android:text="Start Connection"
android:id="#+id/btnstartConnection"
android:layout_width="189dp"
android:layout_height="50dp"
android:layout_below="#id/btnDiscoverable_on_off"
android:background="#drawable/selector"/>
</RelativeLayout>
MainActivity
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener{
BluetoothConnection myBluetoothConnection ;
private static final UUID myUUID = UUID.fromString("8ce255c0-200a-11e0-ac64-0800200c9a66");
BluetoothDevice myBluetoothDevice ;
TextView informations ;
BluetoothAdapter mBluetoothAdapter;
Button btnEnableDisable_Discoverable;
EditText edt ;
Button btnSend ;
Button btnstartconnection ;
public ArrayList<BluetoothDevice> mBTDevices = new ArrayList<>();
public deviceList mDeviceListAdapter;
ListView lvNewDevices;
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (action.equals(mBluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, mBluetoothAdapter.ERROR);
switch(state){
case BluetoothAdapter.STATE_OFF:
break;
case BluetoothAdapter.STATE_TURNING_OFF:
Toast.makeText(getApplicationContext(), " Turning Off ", Toast.LENGTH_SHORT).show();
break;
case BluetoothAdapter.STATE_ON:
break;
case BluetoothAdapter.STATE_TURNING_ON:
Toast.makeText(getApplicationContext(), " Turning On ", Toast.LENGTH_SHORT).show();
break;
}
}
}
};
/**
* Broadcast Receiver for changes made to bluetooth states such as:
* 1) Discoverability mode on/off or expire.
*/
private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {
int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE, BluetoothAdapter.ERROR);
switch (mode) {
//Device is in Discoverable Mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
break;
//Device not in discoverable mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
break;
case BluetoothAdapter.SCAN_MODE_NONE:
break;
case BluetoothAdapter.STATE_CONNECTING:
Toast.makeText(getApplicationContext(), " Connecting... ", Toast.LENGTH_SHORT).show();
break;
case BluetoothAdapter.STATE_CONNECTED:
Toast.makeText(getApplicationContext(), " Connected ", Toast.LENGTH_SHORT).show();
break;
}
}
}
};
/**
* Broadcast Receiver for listing devices that are not yet paired
* -Executed by btnDiscover() method.
*/
private BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothDevice.ACTION_FOUND)){
BluetoothDevice device = intent.getParcelableExtra (BluetoothDevice.EXTRA_DEVICE);
mBTDevices.add(device);
informations.setText(device.getName() + " : " + device.getAddress());
mDeviceListAdapter = new deviceList(context, R.layout.devicelistview, mBTDevices);
lvNewDevices.setAdapter(mDeviceListAdapter);
}
}
};
/**
* Broadcast Receiver that detects bond state changes (Pairing status changes)
*/
private final BroadcastReceiver mBroadcastReceiver4 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED)){
BluetoothDevice mDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//3 cases:
//case1: bonded already
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDED){
Toast.makeText(getApplicationContext(), " Bonded ", Toast.LENGTH_SHORT).show();
myBluetoothDevice = mDevice ;
}
//case2: creating a bone
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDING) {
Toast.makeText(getApplicationContext(), " Bonding ", Toast.LENGTH_SHORT).show();
}
//case3: breaking a bond
if (mDevice.getBondState() == BluetoothDevice.BOND_NONE) {
Toast.makeText(getApplicationContext(), " Not Bonded ", Toast.LENGTH_SHORT).show(); }
}
}
};
#Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(mBroadcastReceiver1);
unregisterReceiver(mBroadcastReceiver2);
unregisterReceiver(mBroadcastReceiver3);
unregisterReceiver(mBroadcastReceiver4);
//mBluetoothAdapter.cancelDiscovery();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnONOFF = (Button) findViewById(R.id.btnONOFF);
btnSend = (Button) findViewById(R.id.sendBtn);
edt = (EditText) findViewById(R.id.edt);
btnstartconnection= (Button) findViewById(R.id.btnstartConnection);
informations = (TextView) findViewById(R.id.information);
btnEnableDisable_Discoverable = (Button) findViewById(R.id.btnDiscoverable_on_off);
lvNewDevices = (ListView) findViewById(R.id.lvNewDevices);
mBTDevices = new ArrayList<>();
//Broadcasts when bond state changes (ie:pairing)
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
registerReceiver(mBroadcastReceiver4, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
lvNewDevices.setOnItemClickListener(MainActivity.this);
btnONOFF.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
enableDisableBT();
}
});
btnstartconnection.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startConnection ();
}
});
btnSend.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
byte [] bytes = edt.getText().toString().getBytes(Charset.defaultCharset());
myBluetoothConnection.write(bytes);
}
});
}
public void startConnection (){
StartBluetoothConnetion(myBluetoothDevice,myUUID);
}
public void StartBluetoothConnetion(BluetoothDevice device , UUID myUUID){
myBluetoothConnection.startClient(device,myUUID);
}
public void enableDisableBT(){
if(mBluetoothAdapter == null){
}
if(!mBluetoothAdapter.isEnabled()){
Toast.makeText(getApplicationContext(), " Enabling Bluetooth ", Toast.LENGTH_SHORT).show();
Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBTIntent);
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
if(mBluetoothAdapter.isEnabled()){
Toast.makeText(getApplicationContext(), " Disabling Bluetooth ", Toast.LENGTH_SHORT).show();
mBluetoothAdapter.disable();
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
}
public void btnEnableDisable_Discoverable(View view) {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
IntentFilter intentFilter = new IntentFilter(mBluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
registerReceiver(mBroadcastReceiver2,intentFilter);
}
public void btnDiscover(View view) {
Toast.makeText(getApplicationContext(), " Searching... ", Toast.LENGTH_SHORT).show();
if(mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.cancelDiscovery();
//check BT permissions in manifest
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
if(!mBluetoothAdapter.isDiscovering()){
//check BT permissions in manifest
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
//first cancel discovery because its very memory intensive.
mBluetoothAdapter.cancelDiscovery();
String deviceName = mBTDevices.get(i).getName();
String deviceAddress = mBTDevices.get(i).getAddress();
informations.setText(deviceName);
informations.setText(deviceAddress);
//create the bond.
//NOTE: Requires API 17+? I think this is JellyBean
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2){
Toast.makeText(getApplicationContext(), " Paring with " + deviceName, Toast.LENGTH_SHORT).show();
mBTDevices.get(i).createBond();
myBluetoothDevice = mBTDevices.get(i);
myBluetoothConnection = new BluetoothConnection(MainActivity.this);
}
}}
Mainfest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cy.el.bluetoothtransfer">
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name="com.cy.el.bluetoothtransfer.MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

No resource found that matches the given name (at 'layout_toRightOf' with value '#id/edttxt'). " brecuse there no control of that id
so use android:layout_toRightOf="#+id/edttxt" or define a control with id having edtxt
ask me in case of any query

There are about 3 errors i noted in your layout because the problem is from the layout.
The first is that in the button with button id
android:id="#+id/btnFindUnpairedDevices",
you have the layout_toRightOf and the layout_above set to the same value i.e the #id/edttxt
The second is that when you have a child or sibling relationship in a Relational layout only the id attribute takes a '+' symbol but your layout the textview with
id="#+id/information has
android:layout_below="#+id/lvNewDevices".
I think correcting these should solve the problem.

Bluetooth:onReceive() and registerReceiver() these method never been called

I am developing an application for a Bluetooth client side, and inside this application has a listview that will list out all the connected devices. First, the application will check for the availability of the Bluetooth and then try to connect to another device(Server) , beside that, I initialised the intent filter in the manifest file.
Below is my code :
public class MainActivity extends AppCompatActivity {
ArrayAdapter<String> listAdapter;
ListView listView;
BluetoothAdapter mBluetoothAdapter;
Set<BluetoothDevice> bondedDevices;
private BluetoothSocket socket;
Intent discoverableIntent;
private BluetoothDevice remoteDevice;
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equalsIgnoreCase("android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED"))
{
Log.i("Connect", "Connecting.>>>>");
unregisterReceiver(this);
remoteDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String Temp1 = remoteDevice.getName();
String Temp2 = remoteDevice.getAddress();
listAdapter.add(Temp1 + Temp2);
listView.setAdapter(listAdapter);
new Thread(reader).start();
}
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
IntentFilter intentFilter = new IntentFilter("com.example.jackpowell.bluetoothclient.ACTION_ACL_CONNECTED");
registerReceiver(mReceiver,intentFilter);
startDiscovery();
}
private void startDiscovery() {
mBluetoothAdapter.cancelDiscovery();
mBluetoothAdapter.startDiscovery();
}
public void init() {
listView = (ListView)findViewById(R.id.listView);
listAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,0);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(MainActivity.this, "Bluetooth is not supported in this device", Toast.LENGTH_SHORT).show();
finish();
} else {
if (!mBluetoothAdapter.isEnabled()) {
turnOnBluetooth();
}
}
bondedDevices = mBluetoothAdapter.getBondedDevices();
discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivity(discoverableIntent);
}
private Runnable reader = new Runnable() {
#Override
public void run() {
try {
Log.i("Connect","Connecting...........");
android.util.Log.e("TrackingFlow", "Found: " + remoteDevice.getName());
UUID uuid = UUID.fromString("a60f35f0-b93a-11de-8a19-03002011c456");
socket = remoteDevice.createRfcommSocketToServiceRecord(uuid);
socket.connect();
} catch (Exception e) {
e.printStackTrace();
}
}
};
private void turnOnBluetooth() {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
Toast.makeText(getApplicationContext(), "Bluetooth must be enabled to continue", Toast.LENGTH_SHORT).show();
finish();
}
}
#Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(mReceiver);
}
}
my manifest:
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<receiver android:name="bluetoothclient">
<intent-filter>
<action android:name="android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED" />
</intent-filter>
</receiver>
The problem now is onReceive() and registerReceiver() these method never been called, or maybe it already called, I just dont get it. If these method were called, the log cat should be displaying the log command. Why are these method never been called? thank you in advance!

The action name is "android.bluetooth.device.action.ACL_CONNECTED" (to use in manifest) or BluetoothDevice.ACTION_ACL_CONNECTED (to use in code, for intent filter). Action names in your code seem wrong.
Note, to register receiver in manifest the receiver name should be public class based on BroadcastReceiver, not sure what is the "bluetoothclient" meaning in the code above (you didn't show the receiver code).
Usually you don't need both manifest receiver and intent filter receiver in activity, one may be sufficient. The main difference is that manifest receiver can be independent from activity life cycle and receive even when activity is not running.
Try to listen also for ACTION_FOUND (per documentation after startDiscovery you'll receive BluetoothDevice.ACTION_FOUND) and others and try to reduce into minimal example. You need also check result of startDiscovery() which can return false on failure.
Here is slightly modified sample from Discovering devices section:
#Override
protected void onCreate(Bundle savedInstanceState) {
...
// Register for broadcasts
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
registerReceiver(mReceiver, filter);
...
if(!mBluetoothAdapter.startDiscovery()){
Log.e("Bluetooth", "discovery error");
}
}
// Create a BroadcastReceiver for bluetooth actions
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.i("Bluetooth", "got action " + action);
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
Log.i("Bluetooth", "got device " + deviceName );
}
}
};
#Override
protected void onDestroy() {
super.onDestroy();
...
// Don't forget to unregister the ACTION_FOUND receiver.
unregisterReceiver(mReceiver);
}
Also note, per this question/answer, on some devices discovery does not always work as expected and there is a need for workarounds.
By the way, did you check the logcat for other errors, for example denied permissions etc.? You may try to enable location and add location permission.
Here is a working sample to display all devices:
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.testbluetooth"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="17"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
MainActivity.java
package com.example.testbluetooth;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.ViewGroup.LayoutParams;
import android.widget.FrameLayout;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView textView;
StringBuilder text = new StringBuilder();
private void addLine(String line)
{
Log.i(getClass().getSimpleName(), line);
text.append("[bluetooth] ").append(line).append('\n');
if(textView!=null)
textView.setText(text);
}
BluetoothAdapter mBluetoothAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_main);
FrameLayout content = new FrameLayout(this);
textView = new TextView(this);
content.addView(textView, new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
addLine("onCreate");
setContentView(content);
// Register for broadcasts
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
registerReceiver(mReceiver, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
for(BluetoothDevice pairedDevice : mBluetoothAdapter.getBondedDevices())
{
addLine("got paired device " + pairedDevice.getName());
}
if(!mBluetoothAdapter.startDiscovery()){
addLine("ERROR: discovery error");
}
else
{
addLine("starting discovery");
}
}
// Create a BroadcastReceiver for bluetooth actions
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
addLine("got action " + action);
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
//String deviceHardwareAddress = device.getAddress(); // MAC address
addLine("got device " + deviceName );
}
}
};
}

How to receive USB connection status broadcast?

I am trying to detect USB connection in my app, that is, whether or not USB is connected to device.
It's being tested on Marshmallow 6.0.1 (sdk23)
But I'm unable to receive the broadcast actions ACTION_USB_DEVICE_ATTACHED or ACTION_USB_DEVICE_DETACHED..
I tried using both the dynamic way and the AndroidManifest.xml way, neither worked..
Here's my code:
AndroidManifest.xml :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.gokulnc.blah_blah"
android:installLocation="auto"
android:versionCode="15"
android:versionName="1.5.1">
<uses-feature android:name="android.hardware.usb.host" />
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="23" />
<android:uses-permission android:name="android.permission.USB_PERMISSION" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:vmSafeMode="false">
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/DrawerTheme">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<receiver android:name="mUsbReceiver">
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_DETACHED" />
</intent-filter>
</receiver>
</activity>
</application>
</manifest>
MainActivity.java :
public class MainActivity extends AppCompatActivity {
BroadcastReceiver mUsbReceiver;
public void onCreate(Bundle savedInstanceState) {
.....
setBroadcastReceivers();
}
void setBroadcastReceivers() {
//Reference: http://www.codepool.biz/how-to-monitor-usb-events-on-android.html
mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d(LOG_TAG, "Received Broadcast: "+action);
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_ATTACHED.equals(action)) {
updateUSBstatus();
Log.d(LOG_TAG, "USB Connected..");
} else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action)) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (device != null) {
updateUSBstatus();
}
Log.d(LOG_TAG, "USB Disconnected..");
}
}
};
IntentFilter filter = new IntentFilter();
filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
//filter.addAction(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
//filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
registerReceiver(mUsbReceiver , filter);
Log.d(LOG_TAG, "mUsbReceiver Registered");
}
#Override
public void onResume() {
super.onResume();
Log.d(LOG_TAG, "App Resumed..");
//Refernce: https://stackoverflow.com/questions/18015656/cant-receive-broadcast-intent-of-usbmanager-action-usb-device-attached-usbmanag
Intent intent = getIntent();
if (intent != null) {
if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) {
Toast.makeText(getApplicationContext(), "Attached", Toast.LENGTH_SHORT).show();
} else if(intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_DETACHED)) {
Toast.makeText(getApplicationContext(), "Detached", Toast.LENGTH_SHORT).show();
}
}
}
}
I also checked this answer: Can't receive broadcast Intent of UsbManager.ACTION_USB_DEVICE_ATTACHED/UsbManager.ACTION_USB_DEVICE_DETACHED, but it didn't help..
Can someone please point out where I'm wrong??

Maybe the reason it doesn't work is that since Android 6.0, the default USB mode is Charging and, maybe ACTION_USB_DEVICE_ATTACHED doesn't get fired up when connected in that mode..
Instead, now I have another solution:
String usbStateChangeAction = "android.hardware.usb.action.USB_STATE";
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d(LOG_TAG, "Received Broadcast: "+action);
if(action.equalsIgnoreCase(usbStateChangeAction)) { //Check if change in USB state
if(intent.getExtras().getBoolean("connected")) {
// USB was connected
} else {
// USB was disconnected
}
}
}
That is, the broadcast android.hardware.usb.action.USB_STATE is sent whenever there is a toggle in the USB state.
Unlike android.hardware.usb.action.USB_DEVICE_ATTACHED which is broadcasted only when something like a MTP mode is enable, android.hardware.usb.action.USB_STATE is broadcasted whenever it detects an USB connection that's capable of connecting to a host (say computer), irrespective of its current USB Mode like Charging, MTP or whatever.. (it's called USB config to be more precise)

Here the perfect steps to check that external usb connection occur or not in android activity. Just Follow the steps one by one.
In Android Manifest file:
<uses-feature android:name="android.hardware.usb.host" />
<uses-permission android:name="android.permission.USB_PERMISSION" />
Inside your USB checking Activity Tag:
<activity android:name=".USBEnabled">
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<meta-data
android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
android:resource="#xml/device_filter" />
</activity>
Inside your connectivity checking USBEnabled class :
public class USBEnabled extends AppCompatActivity {
private static final String TAG = "UsbHost";
TextView mDeviceText;
Button mConnectButton;
UsbManager mUsbManager;
UsbDevice mDevice;
PendingIntent mPermissionIntent;
private static final int REQUEST_TYPE = 0x80;
private static final int REQUEST = 0x06;
private static final int REQ_VALUE = 0x200;
private static final int REQ_INDEX = 0x00;
private static final int LENGTH = 64;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_usbenabled);
mDeviceText = (TextView) findViewById(R.id.text_status);
mConnectButton = (Button) findViewById(R.id.button_connect);
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
}
#Override
protected void onRestart() {
super.onRestart();
recreate();
}
#Override
protected void onResume() {
super.onResume();
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
updateDeviceList();
}
#Override
protected void onPause() {
super.onPause();
unregisterReceiver(mUsbReceiver);
}
public void onConnectClick(View v) {
if (mDevice == null) {
return;
}
mUsbManager.requestPermission(mDevice, mPermissionIntent);
}
private static final String ACTION_USB_PERMISSION = "com.android.recipes.USB_PERMISSION";
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
UsbDevice device = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)
&& device != null) {
getDeviceStatus(device);
} else {
Log.d(TAG, "permission denied for device " + device);
}
}
}
};
private void getDeviceStatus(UsbDevice device) {
UsbDeviceConnection connection = mUsbManager.openDevice(device);
byte[] buffer = new byte[LENGTH];
connection.controlTransfer(REQUEST_TYPE, REQUEST, REQ_VALUE, REQ_INDEX,
buffer, LENGTH, 2000);
connection.close();
}
private void updateDeviceList() {
HashMap<String, UsbDevice> connectedDevices = mUsbManager
.getDeviceList();
if (connectedDevices.isEmpty()) {
mDevice = null;
mDeviceText.setText("No Devices Currently Connected");
mConnectButton.setEnabled(false);
} else {
for (UsbDevice device : connectedDevices.values()) {
mDevice = device;
}
mDeviceText.setText("USB Device connected");
mConnectButton.setEnabled(true);
}
}}
Inside your class xml file :
<?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">
<Button
android:id="#+id/button_connect"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onConnectClick"
android:text="Connect" />
<TextView
android:id="#+id/text_status"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="22dp" />
<TextView
android:id="#+id/text_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="22dp" />
</LinearLayout>
Now create a new resource directory called xml and create new xml file called device_filter.xml with the following code.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<usb-device />
</resources>
Debug and run the application, it will show external usb device connectivity status without any error. I hope you will get output for your scenario.
Enjoy!!

Can`t run BlueTooth discovery from Service

I can`t run startDiscovery (for BlueTooth) from Service.
Service run from sleep by WakefulBroadcastReceiver (by timer).
Source code of Service:
public class LocationService extends Service implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {
private static final String TAG = "LocationService";
private BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();
#Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "Service onCreate");
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(mBTReceiver, filter);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "Service onStartCommand");
BTscanner();
return START_NOT_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
if (btAdapter != null) {
btAdapter.cancelDiscovery();
}
unregisterReceiver(mBTReceiver);
}
private void BTscanner() {
Log.e(TAG, "==BT: Run BTscanner");
btAdapter.cancelDiscovery();
btAdapter.startDiscovery();
Log.e(TAG, "==BT: End BTscanner");
}
private final BroadcastReceiver mBTReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
Log.e(TAG, "==BT: Started");
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
Log.e(TAG, "==BT: Finished");
} else if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = (BluetoothDevice) intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Log.e(TAG, "==BT: " + device.getAddress());
}
}
};
}
In log i see:
Service onStartCommand
==BT: Run BTscanner
==BT: End BTscanner
but don`t see:
==BT: Started
==BT: Finished
and list of discovered devices.
In Manifest all permissions installed:
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
and service enabled in application field of Manifest:
<service
android:name=".LocationService"
android:enabled="true"
android:exported="true" />
What did I do wrong?
Tnx.

Are you sure that your receiver has not been unregistered in the onDestroy method before having the time to handle any action? I would put a break point in it to see what's happenning in there?

I think, I found a solution.
There were problems when I install and run the application with active Bluetooth on smartphone.
After installing application and manual deactivate/activate Bluetooth device all works fine.
Maybe it was some sort of a hardware failure.
Then reinstall the application twice, and the problem is not repeated.

Putting an android device in USB Host Mode?

For my application I need to make the android device act as the USB Host. It needs to send and receive data from USB connected devices. I have gone through USB Host in Android Developers Site, and developed sample code as follows:
Main.java
public class UsbDemoProjActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btn = (Button)findViewById(R.id.button1);
btn.setOnClickListener( new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "button click", 30).show();
Intent it = new Intent(UsbDemoProjActivity.this,Second.class);
startActivity(it);
}
});
}
}
Second.java:
public class Second extends Activity{
UsbDevice device;
UsbManager mUsbManager;
PendingIntent mPermissionIntent;
private static String ACTION_USB_PERMISSION ="com.android.example.USB_PERMISSION";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
System.out.println("111111111");
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
ACTION_USB_PERMISSION ="com.android.example.USB_PERMISSION";
System.out.println("2222222222");
HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
device = deviceList.get("deviceName");
System.out.println("33333333333");
mPermissionIntent = PendingIntent.getBroadcast(this, 0,
new Intent(ACTION_USB_PERMISSION), 0);
System.out.println("444444444444");
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
System.out.println("555555555555");
registerReceiver(mUsbReceiver, filter);
System.out.println("66666666666");
mUsbManager.requestPermission(device, mPermissionIntent);
}
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
System.out.println("7777777777777");
if (ACTION_USB_PERMISSION.equals(action)) {
synchronized (this) {
System.out.println("88888888888");
UsbDevice device = (UsbDevice)intent.getParcelableExtra(
UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if(device != null){
System.out.println("99999999999999");
//call method to set up device communication
}
} else {
//Log.d(TAG, "permission denied for device " + device);
System.out.println("permission denied for device" + device);
}
}
}
}
};
}
However, when I click on button in Main.java page it is showing an error as:
Unfortunately USBDemoProj has been stopped
and in logcat displaying error as per the below image but here the system.output() lines are displaying which are declared in Second.java class. Can anyone please help me what is the error in my app?
Also, am I using the correct method in my sample code to access devices in USB Host Mode? Can anyone suggest me a better way?

I'm using a slickdev library to talk to my serial device, so I'm not sure about your code. It's not onDataReceived()? That might just be the library's function but...
our manifests should both have this in it:
<uses-feature android:name="android.hardware.usb.host" android:required="true"></uses-feature>
and in the
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
android:resource="#xml/device_filter" />