类继承的时候报can not resolve symbol,高手指教

[dazhi9302]

ack23类继承的时候报can not resolve symbol,symbol ACK...高手指教
代码如下
ACK.JAVA文件
public class ACK
{
int ack(int m,int n)
{
int k;
if (m==0)
k=ack(m-1,1);
else
k=ack(m-1,ack(m,n-1));
return k;
}
ack23.java文件
public class ack23 extends ACK
{
public static void main(String args[])
{
int n=ACK.ack(2,3);
System.out.println(n);
}
}}

两个文件在同一文件夹下,且classpath也设置到类文件所在文件夹,ACK文件也编译成功,
请教是为什么出现这个问题?

[cursor_wang]

你的这个方法int ack(int m,int n) 应该声明为静态的public static int ack(int m,int n)

[小笨和漂向北方]

it really depends on what u want.

u can solve this problem by either re-declaring the ack as static method or defining a new instance of ACK class and then invoking the member method ack.

If you pick the first, then it's no sense to make class ack23 inherit from ACK at all.

[awusoft]

public static void main(String args[])
{
int n=new ACK().ack(2,3);
System.out.println(n);
}

[joejoe1991]

非静态方法不能直接通过类来调用
加上static就行了