I am currently trying to write a programm that gets two variables and calculates them. The problem I am facing is that Java Editor shows me "cannot find symbol".

```
public class neupqinputerror extends JFrame {

    public double haelfteP(double p){

        return p/2.0;
    }
    public double quadratVonHaelfteP(double haelfteP){
        return Math.pow (haelfteP, 2);
    }

    public double wurzelTeil(double quadratVonHaelfteP,double q){
        return quadratVonHaelfteP - q;
    }

    public double wurzelFertig(double wurzelTeil){
        return Math.sqrt(wurzelTeil);
    }

    public double pqFormelPlus(){
        return haelfteP             + wurzelFertig; 
    }

    public double pqFormelMinus(){
        return haelfteP - wurzelFertig; 
    }

    public void jButton1_ActionPerformed(ActionEvent evt) {
        nf_x1.setDouble(pqFormelPlus());
        nf_x2.setDouble(pqFormelMinus());
    }

    public void main(String[] args) {
        double haelfteP;
        double p;
        double q;
        double x1;
        double x2;
        double halbP;
        String qEingabe;
        String pEingabe;

        pEingabe = tf_p.getText();
        p = Double.valueOf(pEingabe);
        qEingabe = tf_q.getText();
        q = Double.valueOf(qEingabe); 
    }

}

```

and that are the mistakes I get.

```
neupqinputerror.java:128:12: error: cannot find symbol
return haelfteP             + wurzelFertig; 
       ^
symbol:   variable haelfteP
location: class neupqinputerror
neupqinputerror.java:128:35: error: cannot find symbol
return haelfteP             + wurzelFertig; 
                              ^
symbol:   variable wurzelFertig
location: class neupqinputerror
neupqinputerror.java:132:12: error: cannot find symbol
return haelfteP - wurzelFertig; 
       ^
symbol:   variable haelfteP
location: class neupqinputerror
neupqinputerror.java:132:23: error: cannot find symbol
return haelfteP - wurzelFertig; 
                  ^
symbol:   variable wurzelFertig
location: class neupqinputerror

```

How can I solve those problems?

Note: `tf_p` and `tf_q` are textfields of the gui

thanks