关于Boolean方法调用的问题，一直报错

报错说明为：
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The method Isn(int) is undefined for the type Even_num
at day07.Even_num.main(Even_num.java:11)

Isn没有定义，把下面函数修改为
public static boolean isEven(int b) { //加上static
然后把调用修改为
result = isEven(n);