Question

So in my little Java program I had declared all my variables in the main method, but I wanted to be able to modify them from anywhere inside the class, so I declared them in the class body instead. Now I am not able to modify them inside the main method anymore. Is the solution for this to declare the variables static? If I were to do so would I still be able to change those variables from inside the main method?

public class MainGUI
{
  int num1= 1366, num2= 528, num3= 482, sum; // declare these static?

  public static void main(String args[])
  {
    sum = num1 + num2+ num3; //compiler tells me "non-static varable cannot be refrenced from a static context"
  }
}

Answer 1

you have to create an instance of your class in order to access non static variables from your static methods in java.

public class MainGUI
{
  int num1= 1366, num2= 528, num3= 482, sum; // declare these static?

  public static void main(String args[])
  {
MainGui m = new MainGUI();
    sum = m.num1 + m.num2+ m.num3; 
  }
}

or make your instance variables static so that you can access them directly without any instance from your static methods .

  public class MainGUI
    {
      static int num1= 1366, num2= 528, num3= 482, sum; // declare these static?

      public static void main(String args[])
      {
        sum = num1 + num2+ num3; 
      }
    }

though, by convention static variables from static methods should be accessed with classname.variablename

      sum =  MainGUI.num1 + MainGUI.num2 + MainGUI.num3; 

please refer to this link about better understanding of different types of variable access