java - 从 main 方法中的类访问包含变量的非静态方法？

Question

我正在学习 java，并试图创建一个简单的程序来帮助我找到一种方法(如果有的话)来访问同一类的 main 方法中的非静态方法。这是我目前所拥有的

import java.util.Scanner;

public class MethodVariables

{

    public int num1;
    public int num2;
    public int add = (num1 + num2);
    public int sub = (num1 - num2);

    public static void main(String[] args)
    {
        Scanner input = new Scanner (System.in);

        System.out.println("Please enter the first number: ");
        String num1 = input.nextLine();
        System.out.println("Please enter the second number: ");
        String num2 = input.nextLine();
        input.close();

        // I know these wouldn't work this way but this is just to show what I am trying to accomplish
        addition(add);    
        subtraction(sub);
    }

    public void addition(int add)
    {
        System.out.println("The sum of the two is: " +add);
    }

    public void subtraction(int sub)
    {
        System.out.println("The diference of the two is: "+sub);
    }
}

如果有人知道我忽略了什么，我将不胜感激。

Answer 1

当然，只需在 main 中创建类的实例:

MethodVariables instance = new MethodVariables();

instance.addition(num1);
instance.subtraction(num2);

由于addition 和subtraction 是实例方法，因此您总是需要类的实例来调用它们。 p>