为什么我需要在这里使用静态？ 在这种情况下，我似乎不需要它

Question

I've just recently picked up Java. This is my first day of coding. I have two classes. One is a class that gets user input and outputs it, and another is a class with its own methods and variables.

CLASS 1:

public class Player {
    // this is my player class
    private static int health;

    public void setHealth(int healthToSet) {
        health = healthToSet;
    }

    public static int getHealth() {
        return health;
    }
}

CLASS 2:

import java.util.Scanner;

public class Obtainer {
    public static void main(String[] args) {
        System.out.println("Enter a number you'd like to set your health    to...");
        Scanner userInput = new Scanner(System.in);
        int givenInt = userInput.nextInt();

        Player newPlayer = new Player();

        newPlayer.setHealth(givenInt);

        int newHealth = Player.getHealth();

        System.out.println("OK, you have set your health to " +       newHealth);

        userInput.close();
    }

}

Eclipse prompted me to add a static modifier my getHealth method. I didn't need to do this with setHealth, after doing private int health; instead of private int health = 100;. I know it says static, but that's after I added the static modifier to that and getHealth after I was prompted to. What is the point of this? What is the difference between getHealth and setHealth aside from the fact that setHealth returns no value and getHealth returns a value? Is that what's making me need to use a static modifier?

Answer 1

You should change int newHealth = Player.getHealth(); to int newHealth = newPlayer.getHealth();

Since you are currently invoking the method on a class and not an object, the method has to be static, therefore the compiler complains if it is not.

Answer 2

Yes, in this case I would not use static variables or method, so I would change to

private int health;

public int getHealth() {...}

int newHealth = newPlayer.getHealth();

Answer 3

You can not access the instance methods with the class name.

Option 1 : newPlayer.getHealth();

Option 2 : add the static modifier to getHealth() if it needs to access by Class name.