写了一些代码，但是不知道为什么不可以运行

[Game-Over]

public class Cards{
	String recipient;

public Cards(String recipient){
	this.recipient = recipient;
}

public void greeting(){
	System.out.println("Dear " + recipient + ":\n");
	System.out.println("Wish you have a wonderful summer!");

}

public class Valentine extends Cards{
private int kisses;
public Valentine(String recipient, int kisses){
super(recipient);
this.kisses = kisses;
}
public void greeting(){
System.out.println("Dear "+ recipient);
System.out.println("Love and kisses, " + kisses);
}}

public class Holiday extends Cards{
public Holiday(String recipient){
super(recipient);
}
public void greeting(){
System.out.println("Dear " + recipient);
System.out.println("Season's Greetings!");
}}

public class Birthday extends Cards{
private int age;
public Birthday(String recipient, int age){
super(recipient);
this.age = age;
}
public void greeting(){
System.out.println("Dear "+ recipient);
System.out.println(" "+ age +"th Birthday!");
}}}

public class CardTest{
	public static void main(String[] args)
	{
		Cards card= new Holiday("Alice");
		card.greeting();

		card= new Valentine("bob", 12);
		card.greeting();

		card = new Birthday("Charlie", 4);
		card.greeting();
	}
}

运行完了之后，不知道为什么会出现这样的情况，求大神帮助
CardTest.java:4: error: cannot find symbol
Cards card= new Holiday("Alice");
^
symbol: class Holiday
location: class CardTest
CardTest.java:7: error: cannot find symbol
card= new Valentine("bob", 12);
^
symbol: class Valentine
location: class CardTest
CardTest.java:10: error: cannot find symbol
card = new Birthday("Charlie", 4);
^
symbol: class Birthday
location: class CardTest
3 errors

[静山晚风]

类都在同一目录下面，最好都是写在一个java文件中，别的类不用public修饰符

[Game-Over]

引用 1 楼 jintianhen1 的回复:

类都在同一目录下面，最好都是写在一个java文件中，别的类不用public修饰符

对不起啊。。没有看懂你说的是什么意思。

[RHuniSoft]

一个文件里可以有多个类，但是只能有一个public类，并且你的main函数要放在该public类中，其他的类不能是public的，代码该这么写

class Cards{
	String recipient;

	public Cards(String recipient){
		this.recipient = recipient;
	}

	public void greeting(){
		System.out.println("Dear " + recipient + ":\n");
		System.out.println("Wish you have a wonderful summer!");

	}
}

class Valentine extends Cards{
	private int kisses;
	public Valentine(String recipient, int kisses){
		super(recipient);
		this.kisses = kisses;
	}
	public void greeting(){
		System.out.println("Dear "+ recipient);
		System.out.println("Love and kisses, " + kisses);
	}
}

class Holiday extends Cards{
	public Holiday(String recipient){
	super(recipient);
	}
	public void greeting(){
	System.out.println("Dear " + recipient);
	System.out.println("Season's Greetings!");
	}
}

class Birthday extends Cards{
	private int age;
	public Birthday(String recipient, int age){
		super(recipient);
		this.age = age;
	}
	public void greeting(){
		System.out.println("Dear "+ recipient);
		System.out.println(" "+ age +"th Birthday!");
	}
}
public class CardTest {

		public static void main(String[] args)
		{
			Cards card= new Holiday("Alice");
			card.greeting();

			card= new Valentine("bob", 12);
			card.greeting();

			card = new Birthday("Charlie", 4);
			card.greeting();
		}
}

[rumlee]

这些类是不是在同一个包中。

[木鱼121]

内部类是动态的，也就是开头以public class开头。而主程序是public static class main。在Java中，类中的静态方法不能直接调用动态方法。只有将某个内部类修饰为静态类，然后才能够在静态类中调用该类的成员变量与成员方法。所以在不做其他变动的情况下，最简单的解决办法是将public class改为public static class.

[放码过来吧]

public class xxx 只能出现一次，class xxx可以出现多次

[静山晚风]

楼主还是用 ecipse开发吧，啥年代了还用cmd编译

[Game-Over]

引用 7 楼 jintianhen1 的回复:

楼主还是用 ecipse开发吧，啥年代了还用cmd编译

不是开发。是学习。。

[Fate-]

Valentine valentine = new Valentine（“”，“”）； 应该用子类去new 吧

[yuhouqingchen_2648]

问题所在就是你没有导包。。

[wang_huanming]

指出几个问题： 1、同一个java文件中只允许有一个public class，其他的都不可以是public的。 2、子类可以重写父类的构造函数，但仅限于重写，而不是重载，也就是说子类的构造函数参数类型、个数都必须与父类的一致，不能有不一致的构造函数出现

[泥称已被使用]

你的文件名是CardTest 么？

[yanweijava]

public class Cards { String recipient; public Cards(){ } public Cards(String recipient){ this.recipient = recipient; } public void greeting(){ System.out.println("Dear " + recipient + ":\n"); System.out.println("Wish you have a wonderful summer!"); } public class Valentine extends Cards{ private int kisses; public Valentine(String recipient, int kisses){ super(recipient); this.kisses = kisses; } public void greeting(){ System.out.println("Dear "+ recipient); System.out.println("Love and kisses, " + kisses); } } public class Holiday extends Cards{ public Holiday(String recipient){ super(recipient); } public void greeting(){ System.out.println("Dear " + recipient); System.out.println("Season's Greetings!"); } } public class Birthday extends Cards{ private int age; public Birthday(String recipient, int age){ super(recipient); this.age = age; } public void greeting(){ System.out.println("Dear "+ recipient); System.out.println(" "+ age +"th Birthday!"); } } public static void main(String[] args) { Cards cards = new Cards(); Cards car = cards.new Holiday("test"); car.greeting(); } } //内部类要通过外部类实例化之后才能实例化