title: Android application crashes every time on startup
body: <p>I started coding my first app in Android Studio, what it should do at this stage is that you click a button with the digit and it outputs it into the textfield. When i run this code the application crashes right on startup and I have no idea what's wrong.</p>
  
  <p>MyActivity.java</p>
  
  <pre><code>package com.example.david.calculator;
  
  import android.app.Activity;
  import android.os.Bundle; 
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.View;
  import android.widget.Button;
  import android.widget.EditText;
  
  import org.w3c.dom.Text;
  
  
  public class MyActivity extends Activity {
  
  EditText results;
  private int number;
  final EditText result = (EditText) findViewById(R.id.number);
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_my);
      Button one = (Button) findViewById(R.id.button);
      one.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
              BtnPressed(1);
          }
      });
  
  }
  
  private void BtnPressed(int i) {
      result.setText(Integer.toString(i));
  }
  
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.my, 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);
  }
  }
  </code></pre>
  
  <p>activity_my.xml</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=".MyActivity"&gt;
  
  &lt;EditText
      android:layout_width="fill_parent"
      android:layout_height="50dp"
      android:id="@+id/number"
      android:layout_alignParentTop="true"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:hint="0"
      android:background="#ffe7e7e7"
      android:textSize="30sp"
      android:gravity="center_vertical|right"
      android:paddingRight="20dp"
      android:editable="true"
      android:enabled="true"
      android:numeric="integer|signed|decimal" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="1"
      android:id="@+id/button"
      android:layout_below="@+id/number"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_marginTop="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="2"
      android:id="@+id/button2"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button"
      android:layout_toRightOf="@+id/button"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="3"
      android:id="@+id/button3"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button2"
      android:layout_toRightOf="@+id/button2"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="4"
      android:id="@+id/button4"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_below="@+id/button"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:layout_marginTop="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="5"
      android:id="@+id/button5"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button4"
      android:layout_toRightOf="@+id/button4"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="6"
      android:id="@+id/button6"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button5"
      android:layout_toRightOf="@+id/button5"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="7"
      android:id="@+id/button7"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_below="@+id/button4"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:layout_marginTop="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="8"
      android:id="@+id/button8"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button7"
      android:layout_toRightOf="@+id/button7"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="9"
      android:id="@+id/button9"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button8"
      android:layout_toRightOf="@+id/button8"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="0"
      android:id="@+id/button11"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_below="@+id/button7"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:layout_marginTop="10dp" /&gt;
  
  &lt;Button
      android:layout_width="160dp"
      android:layout_height="75dp"
      android:text="="
      android:id="@+id/button12"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button11"
      android:layout_toRightOf="@+id/button11"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="+"
      android:id="@+id/button13"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button3"
      android:layout_toRightOf="@+id/button3"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="-"
      android:id="@+id/button14"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button6"
      android:layout_toRightOf="@+id/button6"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="*"
      android:id="@+id/button15"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button9"
      android:layout_toRightOf="@+id/button9"
      android:layout_marginLeft="10dp" /&gt;
  
  &lt;Button
      android:layout_width="75dp"
      android:layout_height="75dp"
      android:text="/"
      android:id="@+id/button16"
      android:textSize="50sp"
      android:background="#ff0fdf22"
      android:layout_alignTop="@+id/button12"
      android:layout_toRightOf="@+id/button12"
      android:layout_marginLeft="10dp" /&gt;
  </code></pre>
  
  <p></p>
  
  <p>Logcat:</p>
  
  <pre><code>07-24 16:30:07.894  26564-26564/com.example.david.calculator D/AndroidRuntime﹕ Shutting down VM
  07-24 16:30:07.894  26564-26564/com.example.david.calculator W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4190aba8)
  07-24 16:30:07.899  26564-26564/com.example.david.calculator E/AndroidRuntime﹕ FATAL      EXCEPTION: main
  Process: com.example.david.calculator, PID: 26564
  java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.david.calculator/com.example.david.calculator.MyActivity}: java.lang.NullPointerException
          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
          at android.app.ActivityThread.access$800(ActivityThread.java:135)
          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
          at android.os.Handler.dispatchMessage(Handler.java:102)
          at android.os.Looper.loop(Looper.java:136)
          at android.app.ActivityThread.main(ActivityThread.java:5001)
          at java.lang.reflect.Method.invokeNative(Native Method)
          at java.lang.reflect.Method.invoke(Method.java:515)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
          at dalvik.system.NativeStart.main(Native Method)
   Caused by: java.lang.NullPointerException
          at android.app.Activity.findViewById(Activity.java:1884)
          at com.example.david.calculator.MyActivity.&lt;init&gt;(MyActivity.java:18)
          at java.lang.Class.newInstanceImpl(Native Method)
          at java.lang.Class.newInstance(Class.java:1208)
          at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
          at android.app.ActivityThread.access$800(ActivityThread.java:135)
          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
          at android.os.Handler.dispatchMessage(Handler.java:102)  
          at android.os.Looper.loop(Looper.java:136)
          at android.app.ActivityThread.main(ActivityThread.java:5001)
          at java.lang.reflect.Method.invokeNative(Native Method)
          at java.lang.reflect.Method.invoke(Method.java:515)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
          at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>Thank you very much for all the replies.</p>
  
  <p>            </p>