title: FATAL EXCEPTION: main in android
body: <p>I am a very beginner in field of Android programming.
  I was just trying to develop a sample app.
  Here's the project:</p>
  
  <pre><code>public class CalcActivity extends Activity implements OnClickListener{
  
  EditText input = (EditText) findViewById(R.id.input);
  Button one = (Button) findViewById(R.id.button1);
  TextView out = (TextView) findViewById(R.id.output);
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_calc);
      //one.setOnClickListener(this);
  }
  public void onClick(View v){
  
    input.setText("HI");
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.calc, menu);
      return true;
  }
  
  }
  </code></pre>