title: Null pointer exception on button send
body: <p>Please find below the main class</p>
  
  <pre><code>package com.example.myfirstapp;
  
  import android.content.Intent;
  import android.graphics.drawable.Drawable;
  import android.os.Bundle;
  import android.support.v4.app.Fragment;
  import android.support.v7.app.ActionBarActivity;
  import android.view.LayoutInflater;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.View;
  import android.view.ViewGroup;
  import android.view.View.OnClickListener;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.Spinner;
  
  public class MainActivity extends ActionBarActivity {
  
  public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
  
  public void addListenerOnSpinnerItemSelection() {
      spinner = (Spinner) findViewById(R.id.spinner);
      spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
  
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.main, 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();
      if (id == R.id.action_settings) {
          return true;
      }
      return super.onOptionsItemSelected(item);
  }
  
  /**
   * A placeholder fragment containing a simple view.
   */
  public static class PlaceholderFragment extends Fragment {
  
      public PlaceholderFragment() {
      }
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View rootView = inflater.inflate(R.layout.fragment_main, container,
                  false);
          return rootView;
      }
  }
  
  Button buttonSend;
  EditText textTo;
  EditText textSubject;
  EditText textMessageContact;
  EditText textMessageEmail;
  EditText textMessageAmount;
  Spinner spinner;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      if (savedInstanceState == null) {
          getSupportFragmentManager().beginTransaction()
                  .add(R.id.container, new    PlaceholderFragment()).commit();
      }
  
      buttonSend = (Button) findViewById(R.id.buttonSend);
      textTo = (EditText) findViewById(R.id.editTextSendTo);
      textSubject = (EditText) findViewById(R.id.editTextName);
      textMessageContact = (EditText) findViewById(R.id.editTextContact);
      textMessageEmail = (EditText) findViewById(R.id.editTextEmail);
      textMessageAmount = (EditText) findViewById(R.id.editTextAmount);
      spinner = (Spinner) findViewById(R.id.spinner);
      buttonSend.setOnClickListener(new OnClickListener() {
          @Override
          public void onClick(View v) {
  
              String to = textTo.getText().toString();
              String subject = textSubject.getText().toString();
  
              Intent email = new Intent(Intent.ACTION_SEND);
              email.putExtra(Intent.EXTRA_EMAIL, new String[] { to });
              email.putExtra(Intent.EXTRA_SUBJECT, subject);
              email.setType("message/rfc822");
              startActivity(Intent.createChooser(email,
                      "Choose an Email client :"));
  
          }
      });
  }
  
    }
  </code></pre>
  
  <p>Also please find below the xml file</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" &gt;
  
  &lt;!-- android:background="@drawable/mmm_bg" --&gt;
  
  &lt;TableLayout
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="center"
      android:layout_marginTop="40dip" &gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewName"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Name:"
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextName"
              android:layout_height="wrap_content"
              android:layout_gravity="top|center_horizontal"
              android:layout_weight="3"
              android:ems="10"
              android:hint="enter the name"
              android:textColor="#000000"
              android:textStyle="bold" &gt;
  
              &lt;requestFocus /&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewContact"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Contact:"
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextContact"
              android:layout_height="wrap_content"
              android:layout_gravity="top|center_horizontal"
              android:layout_weight="3"
              android:ems="10"
              android:hint="enter the contact no."
              android:textStyle="bold" &gt;
  
              &lt;requestFocus /&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewEmail"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Email: "
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextEmail"
              android:layout_height="wrap_content"
              android:layout_gravity="top|center_horizontal"
              android:layout_weight="3"
              android:ems="10"
              android:hint="enter the email address"
              android:textColorHint="#008080" &gt;
  
              &lt;requestFocus /&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewProduct"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Product:"
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;Spinner
              android:id="@+id/spinner"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:entries="@array/product_array" /&gt;
  
          &lt;requestFocus /&gt;
  
          &lt;EditText&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewAmount"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Amount:"
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextAmount"
              android:layout_height="wrap_content"
              android:layout_gravity="top|center_horizontal"
              android:layout_weight="3"
              android:ems="10"
              android:hint="enter the amount"
              android:textStyle="bold" &gt;
  
              &lt;requestFocus /&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
  
      &lt;TableRow&gt;
  
          &lt;TextView
              android:id="@+id/textViewSendTo"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="right"
              android:padding="10dip"
              android:text="Send To:"
              android:textColor="#FF0000"
              android:textStyle="bold" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextSendTo"
              android:layout_height="wrap_content"
              android:layout_gravity="top|center_horizontal"
              android:layout_weight="3"
              android:ems="10"
              android:hint="reciever&amp;apos;s email address"
              android:textStyle="bold" &gt;
  
              &lt;requestFocus /&gt;
          &lt;/EditText&gt;
      &lt;/TableRow&gt;
    &lt;/TableLayout&gt;
  
    &lt;LinearLayout
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="10dip"
      android:gravity="center"
      android:orientation="horizontal"
      android:weightSum="3" &gt;
  
      &lt;Button
          android:id="@+id/buttonSend"
          android:layout_width="0dip"
          android:layout_height="fill_parent"
          android:layout_weight="1"
          android:text="Send" /&gt;
     &lt;/LinearLayout&gt;
  
    &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>please find below the log cat</p>
  
  <pre><code>05-13 09:03:49.935: E/AndroidRuntime(14062): Caused by: java.lang.NullPointerException
  05-13 09:03:49.935: E/AndroidRuntime(14062):    at           com.example.myfirstapp.MainActivity.onCreate(MainActivity.java:89)
  05-13 09:03:49.935: E/AndroidRuntime(14062):    at   android.app.Activity.performCreate(Activity.java:5231)
  05-13 09:03:49.935: E/AndroidRuntime(14062):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
  05-13 09:03:49.935: E/AndroidRuntime(14062):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
  05-13 09:03:49.935: E/AndroidRuntime(14062):    ... 11 more
  05-13 09:08:50.395: I/Process(14062): Sending signal. PID: 14062 SIG: 9
  </code></pre>
  
  <p>I am trying to create an app which has 4 to 5 textbox and spinner and send button.
  On clicking the send button the email should go to the recipient with the details entered in text boxes. but there occurs null pointer exception. 
  I am unable to solve the problem. Why is the NPE happening and how to resolve it .</p>
  
  <p>Thanks in advance. Please help me to get through this.</p>