Calling non-static methods from other classes [duplicate]

Answer 1

In your code, winningRecord() is specific to the class Class1 itself due to static keywork.

whereas getPoints() in Class2 is specific to an instance of class Class2

It is not possible to access a non static method from a static context.

Answer 2

getPoints can't be static unless wins is static. And if wins is static then there will only ever be one copy of wins, shared by the entire application. You need to decide how many copies of wins you need. (And "singleton's aside, it's generally silly to have a class just for storing one

Answer 3

A key concept in java is the idea of instantiation. A class definition has all the rules for one type of object. Each instance of the object will follow the same rules. For example, if I define

class Ball {
  public void bounce() { 
    // lots of code here
  }
}

Then the system has code for things called Balls which can bounce

If I want two balls...

public class Main {
  public static void main(String args[]) {
    Ball beachBall = new Ball();
    Ball soccerBall = new Ball();

and I can bounce them all I want

    beachBall.bounce();
    beachBall.bounce();
    soccerBall.bounce();
    beachBall.bounce();

but I cannot say

    Ball.bounce();

because that leaves my system with the question "Which ball?"

static methods and variables are not associated with specific instances.

For example:

class Werewolf {
  static boolean fullMoon = false;

  static void setFullMoon(boolean isVisible) {
    fullMoon = isVisible;
    // code code code
  }

  void eatPerson(Person p) {
    // code code code
  }
}

The static method applied to all werewolves so it is called on the class:

Werewolf.fullMoon(true);

The non-static (instance) method applied to a particular werewolf so it is called on an instance.

jeff.eatPerson(chuck);

Jeff is the werewolf. Chuck is the person he eats. Try to ignore the cruel comments. We all started somewhere.