如何从另一个类的静态方法更改静态变量的值

Question

hi guys i got this variable in my first class

public static double credit;

in the constructor of the first class i got

credit=0.0;

then i got this listener-code that shows me the value on the graphic window after the user adds the funds

Catalogo.addCredit(credit);
creditLabel.setText("Credito: " + getCredit()+"€"); 

using those 2 static methods, this for the value return ( in the first class)

public static double getCredit() {
      return credit; }

and for increase the funds i use this one of another class

public static void addCredit(double creditl) {

  JFrame frame = new JFrame();
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
  String cred = JOptionPane.showInputDialog(frame, "Inserisci l'importo da aggiungere:");

  if (cred == null) {
      return; }

  if ((cred.matches("[0-9]*\\.[0-9]+")) || (cred.matches("[0-9]+"))) { //checks if the string is a valid double value or an int value
      double credits = (double) Double.parseDouble(cred); //conversion into double
      if (credits >= 0.0) {
          JOptionPane.showMessageDialog(frame, "Credito aggiornato con successo");
          creditl = creditl + credits;} }

  if (!(cred.matches("[0-9]+")) && !(cred.matches("[0-9]*\\.[0-9]+"))) { //checks if the user didn't insert a correct double or int
      JOptionPane.showMessageDialog(frame, "Importo inserito errato");
      addCredit(creditl); }
}

now the problem is that the credit variable doesn't increase at all and i don't know why it seems that all is good, or maybe am i missing something ? the input goes wel in the mean that it checks for the proper value and then it says that the credit has been updated but it's not and i don't know why this is happening

NOTE: i have tried to make this variable a non static var and renaming all methods to non static but it seems that it's the same thing, same problem

Answer 1

You're not setting the credit class variable anywhere in your code. You have another local variable named creditl , maybe this is a typo that is part of your problem.

Specifically, this line might be the issue:

creditl = creditl + credits;

(In any case, you should revisit your design.)