public class Demo { //成员变量 int a,b,c; //构造方法用于初始化成员变量 public Demo() { a = 10; b = 20; } public int add() { c = a + b; return c; } public static void main(String[] args) { Demo a = new Demo(); System.out.println(a.add()); } } 哈哈现实的效果不错啊