关于类的调用?(新手有关问题)

关于类的调用?(新手问题)
以下是程序的源代码

Java code

class Person {    String name ;    int age ;    void talk()    {        System.out.println("我是:"+name+"今年:"+age);            }}

Java code

class TestPersondemo{    public static void main (String[] args)    {        Person p = new Person();        p.name = "张三";        p.age = 25 ;        p.talk();    }}

Java code

//类名是  TestPersondemo.javaclass Person {    String name ;    int age ;    void talk()    {        System.out.println("我是:"+name+"今年:"+age);            }}public class TestPersondemo{    public static void main (String[] args)    {        Person p = new Person();        p.name = "张三";        p.age = 25 ;        p.talk();    }}