title: NumberFormatingExcepton if App is launched First Time
body: <p>I have 4 <code>TextView</code>s. 3 of them display results of <code>EditText</code> input value in another activity, and it's saved with shared preferences.</p>
  
  <p>The fourth <code>TextView</code> needs to display sum of that previous 3 <code>TextView</code>s.</p>
  
  <p>I get the error: <code>NumberFormatingException invalid double ""</code></p>
  
  <p>This is my code:</p>
  
  <pre><code>// GETTING VALUES FOR FIRST 3 TEXTVIEWS
  textViewRezultat1RMPotisakSKlupe.setText(settings.getString("benchSave", null));
  textViewRezultat1RMCucanj.setText(settings.getString("squatSave", null));
  textViewRezultat1RMMrtvoDizanje.setText(settings.getString("deadSave", null));
  
  //LITTLE BIT OF MATH TO GET VALUE OF FOURTH
  double prvo = Double.parseDouble(textViewRezultat1RMPotisakSKlupe.getText().toString());
  double drugo = Double.parseDouble(textViewRezultat1RMCucanj.getText().toString());
  double trece = Double.parseDouble(textViewRezultat1RMMrtvoDizanje.getText().toString());
  double rezultat = 0;
  
  rezultat = (prvo + drugo + trece);
  
  textViewRezultat1RMUkupno.setText(Double.toString(rezultat));
  </code></pre>
  
  <p>That works like a charm. </p>
  
  <p>The problem is, I get the error I mentioned above if the app is launched for the first time (with no stored data).</p>
  
  <p>Can anyone help me solve it?</p>