title: Error:(53, 43) error: cannot find symbol variable lumn
body: <p>I am new to android studio and learning to develop the android apps,
  I have got an error as stated above and am unable to resolve it. 
  Any kind of help will be appreciated.
  Thank you!!</p>
  
  <p>My ledControl.java code is as follow</p>
  
  <pre><code>package com.led.led;
  
  import android.support.v7.app.ActionBarActivity;
  import android.os.Bundle;
  import android.view.Menu;
  import android.view.MenuItem;
  
  import android.bluetooth.BluetoothSocket;
  import android.content.Intent;
  import android.view.View;
  import android.widget.Button;
  import android.widget.SeekBar;
  import android.widget.TextView;
  import android.widget.Toast;
  import android.app.ProgressDialog;
  import android.bluetooth.BluetoothAdapter;
  import android.bluetooth.BluetoothDevice;
  import android.os.AsyncTask;
  
  import java.io.IOException;
  import java.util.UUID;
  
  
  public class ledControl extends ActionBarActivity {
  
      Button btnOn, btnOff, btnDis;
      SeekBar brightness;
      TextView lumn;
      String address = null;
      private ProgressDialog progress;
      BluetoothAdapter myBluetooth = null;
      BluetoothSocket btSocket = null;
      private boolean isBtConnected = false;
      //SPP UUID. Look for it
      static final UUID myUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
  
      @Override
      protected void onCreate(Bundle savedInstanceState)
      {
          super.onCreate(savedInstanceState);
  
          Intent newint = getIntent();
          address = newint.getStringExtra(DeviceList.EXTRA_ADDRESS); //receive the address of the bluetooth device
  
          //view of the ledControl
          setContentView(R.layout.activity_led_control);
  
          //call the widgtes
          btnOn = (Button)findViewById(R.id.button2);
          btnOff = (Button)findViewById(R.id.button3);
          btnDis = (Button)findViewById(R.id.button4);
          brightness = (SeekBar)findViewById(R.id.seekBar);
          lumn = (TextView)findViewById(R.id.lumn);
  
          new ConnectBT().execute(); //Call the class to connect
  
          //commands to be sent to bluetooth
          btnOn.setOnClickListener(new View.OnClickListener()
          {
              @Override
              public void onClick(View v)
              {
                  turnOnLed();      //method to turn on
              }
          });
  
          btnOff.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View v)
              {
                  turnOffLed();   //method to turn off
              }
          });
  
          btnDis.setOnClickListener(new View.OnClickListener()
          {
              @Override
              public void onClick(View v)
              {
                  Disconnect(); //close connection
              }
          });
  
          brightness.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
              @Override
              public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                  if (fromUser==true)
                  {
                      lumn.setText(String.valueOf(progress));
                      try
                      {
                          btSocket.getOutputStream().write(String.valueOf(progress).getBytes());
                      }
                      catch (IOException e)
                      {
  
                      }
                  }
              }
  
              @Override
              public void onStartTrackingTouch(SeekBar seekBar) {
  
              }
  
              @Override
              public void onStopTrackingTouch(SeekBar seekBar) {
  
              }
          });
      }
  
      private void Disconnect()
      {
          if (btSocket!=null) //If the btSocket is busy
          {
              try
              {
                  btSocket.close(); //close connection
              }
              catch (IOException e)
              { msg("Error");}
          }
          finish(); //return to the first layout
  
      }
  
      private void turnOffLed()
      {
          if (btSocket!=null)
          {
              try
              {
                  btSocket.getOutputStream().write("TF".toString().getBytes());
              }
              catch (IOException e)
              {
                  msg("Error");
              }
          }
      }
  
      private void turnOnLed()
      {
          if (btSocket!=null)
          {
              try
              {
                  btSocket.getOutputStream().write("TO".toString().getBytes());
              }
              catch (IOException e)
              {
                  msg("Error");
              }
          }
      }
  
      // fast way to call Toast
      private void msg(String s)
      {
          Toast.makeText(getApplicationContext(),s,Toast.LENGTH_LONG).show();
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.menu_led_control, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
  
          //noinspection SimplifiableIfStatement
          if (id == R.id.action_settings) {
              return true;
          }
  
          return super.onOptionsItemSelected(item);
      }
  
      private class ConnectBT extends AsyncTask&lt;Void, Void, Void&gt;  // UI thread
      {
          private boolean ConnectSuccess = true; //if it's here, it's almost connected
  
          @Override
          protected void onPreExecute()
          {
              progress = ProgressDialog.show(ledControl.this, "Connecting...", "Please wait!!!");  //show a progress dialog
          }
  
          @Override
          protected Void doInBackground(Void... devices) //while the progress dialog is shown, the connection is done in background
          {
              try
              {
                  if (btSocket == null || !isBtConnected)
                  {
                      myBluetooth = BluetoothAdapter.getDefaultAdapter();//get the mobile bluetooth device
                      BluetoothDevice dispositivo = myBluetooth.getRemoteDevice(address);//connects to the device's address and checks if it's available
                      btSocket = dispositivo.createInsecureRfcommSocketToServiceRecord(myUUID);//create a RFCOMM (SPP) connection
                      BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
                      btSocket.connect();//start connection
                  }
              }
              catch (IOException e)
              {
                  ConnectSuccess = false;//if the try failed, you can check the exception here
              }
              return null;
          }
          @Override
          protected void onPostExecute(Void result) //after the doInBackground, it checks if everything went fine
          {
              super.onPostExecute(result);
  
              if (!ConnectSuccess)
              {
                  msg("Connection Failed. Is it a SPP Bluetooth? Try again.");
                  finish();
              }
              else
              {
                  msg("Connected.");
                  isBtConnected = true;
              }
              progress.dismiss();
          }
      }
  }
  </code></pre>
  
  <p>And the activity_led_control.xml is as below</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
      android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      android:paddingBottom="@dimen/activity_vertical_margin" tools:context="com.led.led.ledControl"&gt;
  
      &lt;TextView android:text="LED Control" android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:id="@+id/textview2" /&gt;
  
      &lt;SeekBar
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:id="@+id/seekBar"
          android:layout_alignParentRight="true"
          android:layout_alignParentEnd="true"
          android:layout_alignParentBottom="true"
          android:layout_alignParentLeft="true"
          android:layout_alignParentStart="true" /&gt;
  
      &lt;TextView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Brightness"
          android:id="@+id/textView3"
          android:layout_above="@+id/seekBar"
          android:layout_alignParentLeft="true"
          android:layout_alignParentStart="true" /&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="ON"
          android:id="@+id/button2"
          android:layout_above="@+id/button3"
          android:layout_centerHorizontal="true" /&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="OFF"
          android:id="@+id/button3"
          android:layout_above="@+id/button4"
          android:layout_alignLeft="@+id/button2"
          android:layout_alignStart="@+id/button2" /&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Disconnect"
          android:id="@+id/button4"
          android:layout_above="@+id/textView3"
          android:layout_alignLeft="@+id/button3"
          android:layout_alignStart="@+id/button3" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>I know that this error is in text field statement but i dont know how to resolve it ?</p>