Help Android studio -bluetooth application crashing

[Kamel Hamdan]

[/IMG] I am currently developing an application that is going to connect to a device via bluetooth and receive data from it. I have 2 main pages for the bluetooth in my app (as you can see in the image below), the first one is "connect to TANGO" and the second one is "Translate". The first button "connect to TANGO" is responsible for finding devices and connecting with them. and the second one "Translate" is the page responsible for receiving the data from the device and viewing it. But for some reason when i open my application and click on either of them, it just takes me back to the main menu. Below is the code for both pages, if someone could please help out and point out the error in the code.

Here's the code for "connect to TANGO" button

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import android.app.Activity;
    import android.bluetooth.BluetoothAdapter;
    import android.bluetooth.BluetoothDevice;
    import java.util.UUID;
    import android.bluetooth.BluetoothServerSocket;
    import android.bluetooth.BluetoothSocket;
    import android.content.Intent;
    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;
    import android.view.View;

    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.ListView;

    import android.widget.Toast;

    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.Set;

    public class connection extends AppCompatActivity  {
Button b1,b2,b3,b4;
private BluetoothAdapter BA;
private Set<BluetoothDevice>pairedDevices;
ListView lv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_connection);

         b1=(Button)findViewById(R.id.button);
         b2=(Button)findViewById(R.id.button2);
         b3=(Button)findViewById(R.id.button3);
         b4=(Button)findViewById(R.id.button4);

         BA = BluetoothAdapter.getDefaultAdapter();
         lv = (ListView)findViewById(R.id.listView);
}

public void on(View v){
    if (!BA.isEnabled()) {
        Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(turnOn, 0);
        Toast.makeText(getApplicationContext(), "Turned on",Toast.LENGTH_LONG).show();
    } else {
        Toast.makeText(getApplicationContext(), "Already on", Toast.LENGTH_LONG).show();
    }
}

public void off(View v){
if (BA.disable());
    Toast.makeText(getApplicationContext(), "Turned off" ,Toast.LENGTH_LONG).show();
}


public  void visible(View v){
    Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
    startActivityForResult(getVisible, 0);
}


public void list(View v){
    pairedDevices = BA.getBondedDevices();

    ArrayList list = new ArrayList();

    for(BluetoothDevice bt : pairedDevices) list.add(bt.getName());
    Toast.makeText(getApplicationContext(), "Showing Paired Devices",Toast.LENGTH_SHORT).show();

    final ArrayAdapter adapter = new  ArrayAdapter(this,android.R.layout.simple_list_item_1, list);

    lv.setAdapter(adapter);
}


public class RandomStringUUID {
    public void main(String[] args) {
        // Creating a random UUID (Universally unique identifier).
        UUID uuid = UUID.randomUUID();
        String randomUUIDString = uuid.toString();

        System.out.println("Random UUID String = " + randomUUIDString);
        System.out.println("UUID version       = " + uuid.version());
        System.out.println("UUID variant       = " + uuid.variant());
    }
}

private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;

public connection(BluetoothDevice device) {
    // Use a temporary object that is later assigned to mmSocket,
    // because mmSocket is final
    BluetoothSocket tmp = null;
    mmDevice = device;

    // Get a BluetoothSocket to connect with the given BluetoothDevice
    try {
        // MY_UUID is the app's UUID string, also used by the server code
        tmp = device.createRfcommSocketToServiceRecord(UUID.randomUUID());
    } catch (IOException e) { }
    mmSocket = tmp;
}

public void run() {
    // Cancel discovery because it will slow down the connection
    BA.cancelDiscovery();

    try {
        // Connect the device through the socket. This will block
        // until it succeeds or throws an exception
        mmSocket.connect();
    } catch (IOException connectException) {
        // Unable to connect; close the socket and get out
        try {
            mmSocket.close();
        } catch (IOException closeException) { }
        return;
    }

    // Do work to manage the connection (in a separate thread)
    manageConnectedSocket(mmSocket);
}

private void manageConnectedSocket(BluetoothSocket mmSocket) {
}

/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
    try {
        mmSocket.close();
    } catch (IOException e) { }
}

public BluetoothDevice getMmDevice() {
    return mmDevice;
}
}

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And that's the code for the "Translate" button

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 import android.bluetooth.BluetoothSocket;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;

    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;

public class display extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display);
}

    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;
    private android.os.Handler mHandler;

    public display (BluetoothSocket socket, Handler mHandler) {
        mmSocket = socket;
        this.mHandler = mHandler;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        // Get the input and output streams, using temp objects because
        // member streams are final
        try {
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) { }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run() {
        byte[] buffer = new byte[1024];  // buffer store for the stream
        int bytes; // bytes returned from read()

        // Keep listening to the InputStream until an exception occurs
        while (true) {
            try {
                // Read from the InputStream
                bytes = mmInStream.read(buffer);
                // Send the obtained bytes to the UI activity
                int MESSAGE_READ = 0;
                mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {
                break;
            }
        }
    }

    /* Call this from the main activity to send data to the remote device */
    public void write(byte[] bytes) {
        try {
            mmOutStream.write(bytes);
        } catch (IOException e) { }
    }

    /* Call this from the main activity to shutdown the connection */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }
    }
    }

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