黑马程序员Java零基础视频教程_上部-200-1

1-5
常用cmd命令
dir可以查看隐藏的文件，
exit 退出

6-20

20-30




30-40


37 三元表达式

switch新特性

统计

while







continue

break



50
















70

ctrl+alt+M 自动抽取方法





选中一个要改的，shift+F6 同时改方法中的全部



78




88

99


倒序遍历




106
退出while循环


121 static




129 多态






多态案例

package com.itheima.duotai;

public class Animal {
    private int age;
    private String color;

    public Animal() {
    }

    public Animal(int age, String color) {
        this.age = age;
        this.color = color;
    }

    public int getAge() {
        return age;
    }

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

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }
    public void eat(String something){
        System.out.println("动物在吃"+something);
    }
}

package com.itheima.duotai;

public class Dog extends Animal{
    public Dog() {
    }

    public Dog(int age, String color) {
        super(age, color);
    }

    @Override
    public void eat(String something) {
//        super.eat(something);
        System.out.println(getAge()+"岁的"+getColor()+"狗在吃"+something);
    }
    public void lookHome(){
        System.out.println("狗在看家");
    }
}

package com.itheima.duotai;

public class Cat extends Animal{
    public Cat() {
    }

    public Cat(int age, String color) {
        super(age, color);
    }

    @Override
    public void eat(String something) {
        System.out.println(getAge()+"岁的"+getColor()+"猫在吃"+something);
    }
    public void catchMouse(){
        System.out.println("猫在抓老鼠");
    }
}

package com.itheima.duotai;

public class Person {
    private String name;
    private int age;

    public Person() {
    }

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    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 void keepPet(Dog dog,String something){
//        System.out.println("年龄"+age+"岁的"+name+"养了"+dog.getAge()+"岁的"+dog.getColor()+"的狗");
//        dog.eat(something);
//    }
//    public void keepPet(Cat cat,String something){
//        System.out.println("年龄"+age+"岁的"+name+"养了"+cat.getAge()+"岁的"+cat.getColor()+"的猫");
//        cat.eat(something);
//    }

//    public void keepPet(Animal a,String something){
//        if (a instanceof Dog dog){
//            System.out.println("年龄"+age+"岁的"+name+"养了"+a.getAge()+"岁的"+a.getColor()+"的动物");
//            dog.eat(something);
//            dog.lookHome();
//        }else if (a instanceof Cat cat){
//            System.out.println("年龄"+age+"岁的"+name+"养了"+cat.getAge()+"岁的"+cat.getColor()+"的动物");
//            cat.eat(something);
//            cat.catchMouse();
//        }else {
//            System.out.println("没有这种动物");
//        }
//    }

    public void keepPet(Animal a, String something) {
        if (a instanceof Dog) {
            Dog dog = (Dog) a;
            System.out.println("年龄" + age + "岁的" + name + "养了" + a.getAge() + "岁的" + a.getColor() + "的动物");
            dog.eat(something);
            dog.lookHome();
        } else if (a instanceof Cat ) {
            Cat cat = (Cat) a;
            System.out.println("年龄" + age + "岁的" + name + "养了" + cat.getAge() + "岁的" + cat.getColor() + "的动物");
            cat.eat(something);
            cat.catchMouse();
        } else {
            System.out.println("没有这种动物");
        }
    }
}

package com.itheima.duotai;

public class Test {
    public static void main(String[] args) {
//        Person p1 = new Person("老王",30);
//        Dog dog = new Dog(3,"黑色");
//        p1.keepPet(dog,"骨头");
//
//        Person p2 = new Person("老李",20);
//        Cat cat = new Cat(2, "黄色");
//        p2.keepPet(cat,"鱼");

        Person p1 = new Person("老王", 30);
        Dog dog = new Dog(3, "黑色");
        p1.keepPet(dog, "骨头");

        Cat cat = new Cat(2, "黄色");
        p1.keepPet(cat,"鱼");
    }
}

133


136接口

package com.itheima.opp;

public abstract class Animal {
    private String name;
    private String age;

    public Animal() {
    }

    public Animal(String name, String age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }
    public abstract void eat();
}

package com.itheima.opp;

public interface Swim {
    public abstract void swim();
}

package com.itheima.opp;

public class Rabbit extends Animal{
    public Rabbit() {
    }

    public Rabbit(String name, String age) {
        super(name, age);
    }

    @Override
    public void eat() {
        System.out.println("兔子吃");
    }
}

package com.itheima.opp;

public class Frog extends Animal implements Swim{
    public Frog() {
    }

    public Frog(String name, String age) {
        super(name, age);
    }

    @Override
    public void eat() {
        System.out.println("青蛙在吃虫子");
    }

    @Override
    public void swim() {
        System.out.println("青蛙在游泳");
    }
}

package com.itheima.opp;

public class Dog extends Animal implements Swim{
    public Dog() {
    }

    public Dog(String name, String age) {
        super(name, age);
    }

    @Override
    public void eat() {
        System.out.println("狗在吃骨头");
    }

    @Override
    public void swim() {
        System.out.println("狗在游泳");
    }
}

package com.itheima.opp;

public class Test {
    public static void main(String[] args) {
        Frog frog = new Frog("forg","1");
        frog.eat();
        frog.swim();
    }
}

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