类作为成员变量类型

//游戏当中的英雄角色类
public class Hero {

    private String name;//英雄名字
    private int age;//英雄的年龄
    private Weapon weapon;//英雄的武器

    public Hero() {
    }

    public Hero(String name, int age, Weapon weapon) {
        this.name = name;
        this.age = age;
        this.weapon = weapon;
    }

    public void attack(){
        System.out.println("年龄为"+age+"的"+name+"用"+weapon.getCode()+"攻击敌方");
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Weapon getWeapon() {
        return weapon;
    }

    public void setWeapon(Weapon weapon) {
        this.weapon = weapon;
    }
}
=====================================

public class DemoMain {
    public static void main(String[] args) {
        //创建一个英雄角色
        Hero hero=new Hero();
        //为英雄起一个名字，并且设置年龄
        hero.setName("盖伦");
        hero.setAge(20);
        //创建一个武器的对象
        Weapon weapon=new Weapon("多兰剑");
        //为英雄配备武器
        hero.setWeapon(weapon);

        hero.attack();//年龄为20的盖伦用多兰剑攻击敌方
    }
}
==================================

public class Weapon {

    private String code;//武器的代号

    public Weapon() {
    }

    public Weapon(String code) {
        this.code = code;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }
}