public class Nianlin{
private String name="java私塾的";
private int age=2;
public void f(){
age=1000;
System.out.println(name+"年龄是"+age+"年");
}
public static void main(String[] args){
Nianlin c=new Nianlin();
c.f();
}
}
已解决。(new个对象后先初始化类的成员变量。)