编写Person类，包含3个属性name(String)\age(int)\nationality(String), 1个方法void Speak(); 编写HelloChina类，包含1个属性Person

，1个方法void sayHello(); 在sayHello()方法中调用Person类的Speak()方法，输出"Hello, China!"。

以下是Person类的代码：

public class Person {
    private String name;
    private int age;
    private String nationality;
    
    public Person(String name, int age, String nationality) {
        this.name = name;
        this.age = age;
        this.nationality = nationality;
    }
    
    public void Speak() {
        System.out.println("Hello, I am " + name + ". I am " + age + " years old. I am from " + nationality + ".");
    }
}

以下是HelloChina类的代码：

public class HelloChina {
    private Person person;
    
    public HelloChina(Person person) {
        this.person = person;
    }
    
    public void sayHello() {
        System.out.println("Hello, China!");
        person.Speak();
    }
}

在主函数中，可以这样使用：

Person person = new Person("Tom", 20, "USA");
HelloChina hello = new HelloChina(person);
hello.sayHello();