Question

I am developing a Bluetooth chat application. The problem is that when i enable Bluetooth the application enables Bluetooth but causes force close. the next time i launch the same application(with Bluetooth enabled) it works smoothly ! i have searched and only got some information saying that when i start the intent for enable Bluetooth the code proceeds not waiting for the result of Intent

        public void run() {

        // 1. Check if Bluetooth is Enabled
        if (!blue.isEnabled()) {
            Intent enable_Bluetooth = new Intent(
                    BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enable_Bluetooth, 1);

        }

        // 2. Start Bluetooth Server
        try {
            Server = blue.listenUsingRfcommWithServiceRecord("dhiraj",
                    MY_UUID);

Answer 1

first:

Declare the Bluetooth permission(s) in your application manifest file.
For example:

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

Setting up bluetooth:

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
// Device does not support Bluetooth
}

Enable bluetooth:

if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

Finding devices:

Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
// If there are paired devices
if (pairedDevices.size() > 0) {
// Loop through paired devices
for (BluetoothDevice device : pairedDevices) {
    // Add the name and address to an array adapter to show in a ListView
    mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
}

discovering devices:

// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();
    // When discovery finds a device
    if (BluetoothDevice.ACTION_FOUND.equals(action)) {
        // Get the BluetoothDevice object from the Intent
        BluetoothDevice device =     
intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
        // Add the name and address to an array adapter to show in a ListView
        mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
    }
}
};
// Register the BroadcastReceiver
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy

Enabling discovery

Intent discoverableIntent = new
Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);