How to calculate a value from an action listener

I am building a program with a GUI and i am trying to get the program to calculate if a driver is over or under the limit. I am using an action listener in order to read what the user is going to type in.

public void calculation() {

    if(txtSpeed > txtLimit){

        System.out.println("The dirver is over the limit");
    }
    else{
        System.out.println("The driver is under the limit");
    }

class VhLimitHandler implements ActionListener{ public void actionPerformed(ActionEvent event){

        txtLimit = Double.parseDouble(textLimit.getText());

    }
}

class VhSpeedHandler implements ActionListener{
    public void actionPerformed(ActionEvent event){

        txtSpeed = Double.parseDouble(textSpeed.getText());