How to calculate a triangle area

        double a = Double.parseDouble(jTextField1.getText());
        double b = Double.parseDouble(jTextField2.getText());
        double c = Double.parseDouble(jTextField3.getText());
        double area1;
        double area2;
        double semip;
      
         if (((a+b)>c)&&((a+c)>b)&&((b+c)>a))
         {
             jTextField6.setText("form a triangle");
            
             semip = (a+b+c)/2;
             area1 = (semip*(semip-a)*(semip-b)*(semip-c));
             area2 = (Math.sqrt(area1));
             jTextField4.setText(String.valueOf(NumberFormat.getNumberInstance().format(area2)));
             //jTextField4.setText(String.valueOf(Math.round(area2))); - full the number
        
             if (a==b && b==c)
             {
              jTextField5.setText("equilateral triangle");
             }
             else if (a==b || b==c || a ==c)
             {
              jTextField5.setText("isosceles triangle");
             }
             else
             {
              jTextField5.setText("scalene triangle");
             }
         }
         else
         {
             jTextField6.setText("not form a triangle");
         }