MainActivity.java

package com.example.weightliftingfeedbackapp;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;
 
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;
 
public class MainActivity extends Activity implements OnClickListener {
 
        Button Connect;
        ToggleButton OnOff;
        TextView Result;
        private String dataToSend;
       
        private static final String TAG = "BT";
        private BluetoothAdapter mBluetoothAdapter = null;
        private BluetoothSocket btSocket = null;
        private OutputStream outStream = null;
        private static String address = "XX:XX:XX:XX:XX:XX";
        private static final UUID MY_UUID = UUID
                        .fromString("00001101-0000-1000-8000-00805F9B34FB");
        private InputStream inStream = null;
    Handler handler = new Handler();
    byte delimiter = 10;
    boolean stopWorker = false;
    int readBufferPosition = 0;
    byte[] readBuffer = new byte[1024];
 
        @Override
        protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
 
                Connect = (Button) findViewById(R.id.connect);
                OnOff = (ToggleButton) findViewById(R.id.tgOnOff);
                Result = (TextView) findViewById(R.id.msgArduino);
 
                Connect.setOnClickListener(this);
                OnOff.setOnClickListener(this);
 
                CheckBt();
                BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
                Log.e("BT", device.toString());
 
        }
 
        @Override
        public void onClick(View control) {
                switch (control.getId()) {
                case R.id.connect:
                                Connect();
                        break;
                case R.id.tgOnOff:
                        if (OnOff.isChecked()) {
                                dataToSend = "1";
                                writeData(dataToSend);
                        } else if (!OnOff.isChecked()) {
                                dataToSend = "0";
                                writeData(dataToSend);
                        }
                        break;
                }
        }
 
        private void CheckBt() {
                mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
 
                if (!mBluetoothAdapter.isEnabled()) {
                        Toast.makeText(getApplicationContext(), "Bluetooth Disabled !",
                                        Toast.LENGTH_SHORT).show();
                }
 
                if (mBluetoothAdapter == null) {
                        Toast.makeText(getApplicationContext(),
                                        "Bluetooth null !", Toast.LENGTH_SHORT)
                                        .show();
                }
        }
       
                public void Connect() {
                        Log.d(TAG, address);
                        BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
                        Log.d(TAG, "Connecting to ... " + device);
                        mBluetoothAdapter.cancelDiscovery();
                        try {
                                btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
                                btSocket.connect();
                                Log.d(TAG, "Connection made.");
                        } catch (IOException e) {
                                try {
                                        btSocket.close();
                                } catch (IOException e2) {
                                        Log.d(TAG, "Unable to end the connection");
                                }
                                Log.d(TAG, "Socket creation failed");
                        }
                       
                        beginListenForData();
                }
       
        private void writeData(String data) {
                try {
                        outStream = btSocket.getOutputStream();
                } catch (IOException e) {
                        Log.d(TAG, "Bug BEFORE Sending stuff", e);
                }
 
                String message = data;
                byte[] msgBuffer = message.getBytes();
 
                try {
                        outStream.write(msgBuffer);
                } catch (IOException e) {
                        Log.d(TAG, "Bug while sending stuff", e);
                }
        }
 
        @Override
        protected void onDestroy() {
                super.onDestroy();
       
                        try {
                                btSocket.close();
                        } catch (IOException e) {
                        }
        }
       
        public void beginListenForData()   {
                 try {
                                inStream = btSocket.getInputStream();
                        } catch (IOException e) {
                        }
                 
                Thread workerThread = new Thread(new Runnable()
                {
                    public void run()
                    {                
                       while(!Thread.currentThread().isInterrupted() && !stopWorker)
                       {
                            try
                            {
                                int bytesAvailable = inStream.available();                        
                                if(bytesAvailable > 0)
                                {
                                    byte[] packetBytes = new byte[bytesAvailable];
                                    inStream.read(packetBytes);
                                    for(int i=0;i<bytesAvailable;i++)
                                    {
                                        byte b = packetBytes[i];
                                        if(b == delimiter)
                                        {
                                            byte[] encodedBytes = new byte[readBufferPosition];
                                            System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
                                            final String data = new String(encodedBytes, "US-ASCII");
                                            readBufferPosition = 0;
                                            handler.post(new Runnable()
                                            {
                                                public void run()
                                                {
                                                       
                                                        if(Result.getText().toString().equals("..")) {
                                                                Result.setText(data);
                                                        } else {
                                                                Result.append("\n"+data);
                                                        }
                                                       
                                                        /* You also can use Result.setText(data); it won't display multilines
                                                        */
                                                       
                                                }
                                            });
                                        }
                                        else
                                        {
                                            readBuffer[readBufferPosition++] = b;
                                        }
                                    }
                                }
                            }
                            catch (IOException ex)
                            {
                                stopWorker = true;
                            }
                       }
                    }
                });
 
                workerThread.start();
            }
}