title: Set TextView text to what is returned from function in another class
body: <p>I'm new to android and I am making an app as part of an assignment, and can't get this function to return a value - the app closes and I get an error message: "Unfortunately, APP has stopped".</p>
  
  <p>I have two classes, one is the MainActivity and one is a class that I am wanting to use to do arithmetic, and they are:</p>
  
  <pre><code>import com.calc.Calculation;
  
  public class MainActivity extends Activity {
    private Calculation util;   
    calculate = (Button) findViewById(R.id.btnCalc);
    private TextView tvMultiply;
  
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvMultiply = (TextView) findViewById(R.id.tvMult);
     }
  
    btnCalc.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
      tvMiltiply.setText(String.valueOf(util.CalculateMult(4,6)));
      }
    });
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>package com.calc;
  
  public class Calculation{
  
      public int CalculateMult(int numOne, int numTwo)
      {
      return numOne * numTwo;
      }
  
  }
  </code></pre>
  
  <p>I've tried a few alternatives but to no avail. It's going to be something simple that I am not doing quite right. </p>
  
  <p>Any help appreciated.</p>
  
  <p>Thanks</p>