java 抽象类示例详解

public abstract class Animal {
    //Animal类此时就是一个抽象类。
}
class Dog extends Animal {
    //Dog类继承了Animal类，是Animal类的子类。
}

package knowledge.polymorphism.about_abstract.introduction;
public abstract class Animal {   /** 父类 */
    //将Animal类中的eat() 方法定义为抽象类，具体实现延迟到子类。
    public abstract void eat();
}
class Dog extends Animal {      /** 子类 */
    //子类重写父类的抽象方法，也称为子类实现了该抽象方法。
    public void eat() {
        System.out.println("狗是杂食性动物，喜食肉类，喂养时应该以动物蛋白为主，素食为辅。");
    }
}
class Test {
    public static void main(String[] args) {
        Dog dog = new Dog();
        dog.eat();
    }
}

//抽象类
public abstract class Animal {
    //抽象方法
    public abstract void eat();        //抽象方法最后加一个分号即可，不可以有大括号。
}

package knowledge.polymorphism.about_abstract.character;
public abstract class Food {            /** 父类 : Food类 */
    //记住，抽象方法没有方法体
    public abstract void showNutrition();
}
class Meat extends Food {               /** 子类 : Meat类 */
    @Override
    public void showNutrition() {
        System.out.println("肉类是蛋白质、脂肪、维生素B2、维生素B1、烟酸和铁的重要来源。");
    }
}
abstract class Fruit extends Food {     /** 子类 : Fruit类 */
}
class Test {                            /** 测试类 : Test类 */
    public static void main(String[] args) {
        Meat meat = new Meat();
        meat.showNutrition();
    }
}

class CiLi extends Fruit {
    @Override
    public void showNutrition() {
        System.out.println("刺梨是当之无愧的水果界的VC之王，VC含量高达2585mg/100g！");
    }
}
class Test {
    public static void main(String[] args) {/** 测试类 : Test类 */
        Meat meat = new Meat();
        meat.showNutrition();
        System.out.println("----------------------------------------");
        CiLi ciLi = new CiLi();
        ciLi.showNutrition();
    }
}

package knowledge.polymorphism.about_abstract.about_members;
public abstract class Fruit {        //Fruit类是抽象类
//抽象类中可定义的成员：
    //1.非静态变量和静态变量
    private String name = "水果名儿是有长有短";
    private static String size = "水果的大小是有大有小";
    //2.非静态常量和静态常量
    public final String COLOR = "水果的颜色是五光十色";
    public static final String FORM = "水果的形态是千奇百怪";
    //3.抽象方法和非抽象方法
    public abstract void nutrition();
    private final static void suitCrowds() {
        System.out.println("人人都适合吃水果！");
    }
    public void invokeSuitCrowds() {
        Fruit.suitCrowds();
    }
    //4.构造器可以重载
    public Fruit() {
        System.out.println("Fruit's name = " + name);
    }
    public Fruit(String name) {
        this.name = name;
    }
}

package knowledge.polymorphism.about_abstract.exercise;
public abstract class Knights {             /** 骑士类 */
    private String name;
    private int age;
    private String sex;
    public Knights() {
    }
    public Knights(String name, int age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }
    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 String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public abstract void elemental_skill();
    public abstract void elemental_burst();
    public void printInfo() {
        System.out.println("西风骑士——" + getName() + "，" + getAge() + "岁，性别" + getSex());
    }
}
class Qin extends Knights{                  /** 琴类 */
    public Qin(String name, int age, String sex) {
        super(name, age, sex);
    }
    @Override
    public void elemental_skill() {
        System.out.println("琴的元素战技是风压箭。");
    }
    @Override
    public void elemental_burst() {
        System.out.println("琴的元素战技是蒲公英之风。");
    }
}
class Keli extends Knights{                 /** 可莉类 */
    public Keli(String name, int age, String sex) {
        super(name, age, sex);
    }
    @Override
    public void elemental_skill() {
        System.out.println("可莉的元素战技是蹦蹦炸弹。");
    }
    @Override
    public void elemental_burst() {
        System.out.println("可莉的元素战技是轰轰火花。");
    }
}
class Youla extends Knights{                /** 优菈类 */
    public Youla(String name, int age, String sex) {
        super(name, age, sex);
    }
    @Override
    public void elemental_skill() {
        System.out.println("优菈的元素战技是冰朝的涡旋。");
    }
    @Override
    public void elemental_burst() {
        System.out.println("优菈的元素战技是凝浪之光剑。");
    }
}
class Test {                                /** 测试类 */
    public static void main(String[] args) {
        Qin qin = new Qin("琴", 22, "female");
        qin.elemental_skill();
        qin.elemental_burst();
        qin.printInfo();
        System.out.println("-------------------------------------------");
        Keli keli = new Keli("可莉", 500, "female");
        keli.elemental_skill();
        keli.elemental_burst();
        keli.printInfo();
        System.out.println("-------------------------------------------");
        Youla youla = new Youla("优菈", 21, "female");
        youla.elemental_skill();
        youla.elemental_burst();
        youla.printInfo();
    }
}