Android listing BLE devices after device scan

Question

Can u provide me the simple code for scanning the nearby BLE devices and list it by device name and MAC ID. I tried this using sample code provided in http://developer.android.com/guide/topics/connectivity/bluetooth-le.html. But didn't work, any reference link or ideas since i am new to BLE app.

Answer 1

This example is based on the developers web you posted and works great for me. This is the code:

DeviceScanActivity.class

package com.example.android.bluetoothlegatt;

import android.app.Activity;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;

public class DeviceScanActivity extends ListActivity {
private LeDeviceListAdapter mLeDeviceListAdapter;
private BluetoothAdapter mBluetoothAdapter;
private boolean mScanning;
private Handler mHandler;

private static final int REQUEST_ENABLE_BT = 1;
// Stops scanning after 10 seconds.
private static final long SCAN_PERIOD = 10000;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getActionBar().setTitle(R.string.title_devices);
    mHandler = new Handler();

    // Use this check to determine whether BLE is supported on the device.  Then you can
    // selectively disable BLE-related features.
    if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
        Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
        finish();
    }
    // Initializes a Bluetooth adapter.  For API level 18 and above, get a reference to
    // BluetoothAdapter through BluetoothManager.
    final BluetoothManager bluetoothManager =
            (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
    mBluetoothAdapter = bluetoothManager.getAdapter();
    // Checks if Bluetooth is supported on the device.
    if (mBluetoothAdapter == null) {
        Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();
        finish();
        return;
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    if (!mScanning) {
        menu.findItem(R.id.menu_stop).setVisible(false);
        menu.findItem(R.id.menu_scan).setVisible(true);
        menu.findItem(R.id.menu_refresh).setActionView(null);
    } else {
        menu.findItem(R.id.menu_stop).setVisible(true);
        menu.findItem(R.id.menu_scan).setVisible(false);
        menu.findItem(R.id.menu_refresh).setActionView(
                R.layout.actionbar_indeterminate_progress);
    }
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.menu_scan:
            mLeDeviceListAdapter.clear();
            scanLeDevice(true);
            break;
        case R.id.menu_stop:
            scanLeDevice(false);
            break;
    }
    return true;
}

@Override
protected void onResume() {
    super.onResume();
    // Ensures Bluetooth is enabled on the device.  If Bluetooth is not currently enabled,
    // fire an intent to display a dialog asking the user to grant permission to enable it.
    if (!mBluetoothAdapter.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    }
    // Initializes list view adapter.
    mLeDeviceListAdapter = new LeDeviceListAdapter();
    setListAdapter(mLeDeviceListAdapter);
    scanLeDevice(true);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // User chose not to enable Bluetooth.
    if (requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_CANCELED) {
        finish();
        return;
    }
    super.onActivityResult(requestCode, resultCode, data);
}

@Override
protected void onPause() {
    super.onPause();
    scanLeDevice(false);
    mLeDeviceListAdapter.clear();
}

private void scanLeDevice(final boolean enable) {
    if (enable) {
        // Stops scanning after a pre-defined scan period.
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                mScanning = false;
                mBluetoothAdapter.stopLeScan(mLeScanCallback);
                invalidateOptionsMenu();
            }
        }, SCAN_PERIOD);
        mScanning = true;
        mBluetoothAdapter.startLeScan(mLeScanCallback);
    } else {
        mScanning = false;
        mBluetoothAdapter.stopLeScan(mLeScanCallback);
    }
    invalidateOptionsMenu();
}

// Adapter for holding devices found through scanning.
private class LeDeviceListAdapter extends BaseAdapter {
    private ArrayList<BluetoothDevice> mLeDevices;
    private LayoutInflater mInflator;

    public LeDeviceListAdapter() {
        super();
        mLeDevices = new ArrayList<BluetoothDevice>();
        mInflator = DeviceScanActivity.this.getLayoutInflater();
    }

    public void addDevice(BluetoothDevice device) {
        if(!mLeDevices.contains(device)) {
            mLeDevices.add(device);
        }
    }

    public BluetoothDevice getDevice(int position) {
        return mLeDevices.get(position);
    }

    public void clear() {
        mLeDevices.clear();
    }

    @Override
    public int getCount() {
        return mLeDevices.size();
    }

    @Override
    public Object getItem(int i) {
        return mLeDevices.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder;
        // General ListView optimization code.
        if (view == null) {
            view = mInflator.inflate(R.layout.listitem_device, null);
            viewHolder = new ViewHolder();
            viewHolder.deviceAddress = (TextView) view.findViewById(R.id.device_address);
            viewHolder.deviceName = (TextView) view.findViewById(R.id.device_name);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }

        BluetoothDevice device = mLeDevices.get(i);
        final String deviceName = device.getName();
        if (deviceName != null && deviceName.length() > 0)
            viewHolder.deviceName.setText(deviceName);
        else
            viewHolder.deviceName.setText(R.string.unknown_device);
        viewHolder.deviceAddress.setText(device.getAddress());

        return view;
    }
}

// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {

    @Override
    public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mLeDeviceListAdapter.addDevice(device);
                mLeDeviceListAdapter.notifyDataSetChanged();
            }
        });
    }
};

static class ViewHolder {
    TextView deviceName;
    TextView deviceAddress;
}

}

The custom layout for the Listview listitem_device.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="wrap_content">
  <TextView android:id="@+id/device_name"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:textSize="24dp"/>
  <TextView android:id="@+id/device_address"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:textSize="12dp"/>
</LinearLayout>

The progress bar on scanning actionbar_indeterminate_progress.xml :

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_height="wrap_content"
         android:layout_width="56dp"
         android:minWidth="56dp">
<ProgressBar android:layout_width="32dp"
             android:layout_height="32dp"
             android:layout_gravity="center"/>
</FrameLayout>

The menu layout main.xml :

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/menu_refresh"
      android:checkable="false"
      android:orderInCategory="1"
      android:showAsAction="ifRoom"/>
<item android:id="@+id/menu_scan"
      android:title="@string/menu_scan"
      android:orderInCategory="100"
      android:showAsAction="ifRoom|withText"/>
<item android:id="@+id/menu_stop"
      android:title="@string/menu_stop"
      android:orderInCategory="101"
      android:showAsAction="ifRoom|withText"/>
</menu>

The strings layout strings.xml :

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="ble_not_supported">BLE is not supported</string>
  <string name="error_bluetooth_not_supported">Bluetooth not supported.</string>
  <string name="unknown_device">Unknown device</string>

  <!-- Menu items -->
  <string name="menu_connect">Connect</string>
  <string name="menu_disconnect">Disconnect</string>
  <string name="menu_scan">Scan</string>
  <string name="menu_stop">Stop</string>
</resources>

And the manifest AndroidManifest.xml :

<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.bluetoothlegatt"
android:versionCode="1"
android:versionName="1.0">

<uses-sdk android:minSdkVersion="18"
    android:targetSdkVersion="19"/>
<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

<application android:label="@string/app_name"
    android:icon="@drawable/ic_launcher"
    android:theme="@android:style/Theme.Holo.Light">
    <activity android:name=".DeviceScanActivity"
        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>

I think this is all. If I missed anything let me now and I fix it. Hope it helps!!

(Bluetooth LE quite sucks in Android yet :D... needs and update fast!)

UPDATE:

Check the full example of BLE scan and connection in GitHub: https://github.com/kodartcha/BLEDeviceScanSample

Answer 2

this is quite old question, but for future readers I just want to propose to check out official source codes provided by Bluetooth SIG:

Application Accelerator

There are small, easy to understand and documented apps for most mobile platforms (Android, iOS, Windows Phone and more) + some materials/tutorials. If you want to start playing with BLE this is the best starting point in my opinion.

Everything is free, but you need to register on the website. As far as I remember there is maybe 1-3 emails by year, all connected with new tools for Bluetooth development.

Darek