title: sum values of jtextfields in one jtextfields
body: <p>I want to find the sum of the jtextfields  (sht1 to sht13) and put the result in llog jtextfield, but it wont work if i dont put values in every jtextfield (sht1 to sht13)
   how can i fix my code so that it takes only the values of the jtextfields that i choose to put values on</p>
  
  <pre><code>private void llogMouseClicked(java.awt.event.MouseEvent evt) {                                  
        try{
        int sht1 = Integer.parseInt(vl1.getText());
        int sht2 = Integer.parseInt(vl2.getText());
        int sht3 = Integer.parseInt(vl3.getText());
        int sht4 = Integer.parseInt(vl4.getText());
        int sht5 = Integer.parseInt(vl5.getText());
        int sht6 = Integer.parseInt(vl6.getText());
        int sht7 = Integer.parseInt(vl7.getText());
        int sht8 = Integer.parseInt(vl8.getText());
        int sht9 = Integer.parseInt(vl9.getText());
        int sht10 = Integer.parseInt(vl10.getText());
        int sht11 = Integer.parseInt(vl11.getText());
        int sht12 = Integer.parseInt(vl12.getText());
        int sht13 = Integer.parseInt(vl13.getText());
   if (vl1.getText()==null||vl2.getText()==null||vl3.getText()==null||vl4.getText()==null||vl5.getText()==null||vl6.getText()==null||vl7.getText()==null||vl8.getText()==null||vl9.getText()==null||vl10.getText()==null||vl11.getText()==null||vl12.getText()==null||vl13.getText()==null){
      sht1=0;
      sht2=0;
      sht3=0;
      sht4=0;
      sht5=0;
      sht6=0;
      sht7=0;
      sht8=0;
      sht9=0;
      sht10=0;
      sht11=0;
      sht12=0;
      sht13=0;
      int sum= sht1 + sht2 + sht3 + sht4 + sht5 + sht6 + sht7 + sht8 + sht9 + sht10 + sht11 + sht12 + sht13;
    llog.setText(""+ sum);}
  </code></pre>