Java由浅入深刨析继承

package com.nz.pojo;

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

package com.nz.pojo;

/**
 * 继承了Person特有的name, age，
 * 没有额外的独有属性和方法
 */
public class Student extends Person{
}

package com.nz.pojo;

/**
 * 继承了Person特有的name, age，
 * 多了自己独有的工资属性还有独有的教书方法
 */
public class Teacher extends Person{

    // 工资
    private double salary ;

    // 特有方法
    public void teach(){
        System.out.println("老师在认真教书！");
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }
}

package com.nz;

import com.nz.pojo.Student;
import com.nz.pojo.Teacher;

public class InheritDemo {
    public static void main(String[] args) {
        Teacher teacher = new Teacher();
        teacher.setName("最爱吃鱼罐头");
        teacher.setAge(18);
        teacher.setSalary(1999.99);
        System.out.println(teacher.getName());
        System.out.println(teacher.getAge());
        System.out.println(teacher.getSalary());
        teacher.teach();

        Student student = new Student();
        student.setName("罐头");
        student.setAge(12);
        //student.setSalary(1999.99); // student没有工资属性，报错！
        System.out.println(student.getName());
        System.out.println(student.getAge());
    }
}

package com.nz;

public class InheritDemo2 {
    public static void main(String[] args) {
        Animal a = new Animal();
        a.eat();
        Cat cat = new Cat();
        cat.eatFish();
    }
}

class Animal {
    void eat() {
        System.out.println("animal : eat");
    }
}

class Cat extends Animal {
    void eat() {
        System.out.println("cat : eat");
    }
    void eatFish() {
        this.eat();   // this 调用自己的方法
        super.eat();  // super 调用父类方法
    }
}

package com.nz;

public class InheritDemo3  {
    public static void main(String[] args) {
        System.out.println("------Teacher 类继承------");
        Teacher teacher = new Teacher();
        Teacher teacher2 = new Teacher("张三");
        System.out.println("------Student 类继承------");
        Student student = new Student();
        Student student2 = new Student("张三三");
    }
}
// 父类
class Person {
    private String name;
    Person(){
        System.out.println("调用了父类的无参构造器: Person()");
    }
    Person(String name) {
        System.out.println("调用了父类的带参构造器: Person(String name)");
        this.name = name;
    }
}
// Teacher子类继承Person
class Teacher extends Person{
    private String name;
    Teacher(){
        // 自动调用父类的无参数构造器 因为会有默认super();
        System.out.println("Teacher");
    }

    public Teacher(String name){
        super("最爱吃鱼罐头");  // 调用父类中带有参数的构造器
        System.out.println("Teacher(String name):"+name);
        this.name = name;
    }
}
// Student子类继承Person
class Student extends Person{
    private String name;

    Student(){
        super("heihei");  // 调用父类中带有参数的构造器
        System.out.println("SubClass2");
    }

    public Student(String name){ // 自动调用父类的无参数构造器
        System.out.println("Student(String name):"+name);
        this.name = name;
    }
}

package com.nz;

public class InheritDemo4 {
}

// 父类
final class Fu {
    private String name;
}

//class Zi extends Fu{ // Cannot inherit from final 'com.nz.Fu' 会显示没办法继承Fu
//}

package com.nz;

public class InheritDemo5 {

    public static void main(String[] args) {
        // 创建子类对象
        Cat lanMao = new Cat();
        // 调用父类继承而来的方法
        lanMao.run();
        // 调用子类重写的方法
        lanMao.sing();

    }
}

class Animal{
    public void sing(){
        System.out.println("动物都可以唱歌！");
    }
    public void run(){
        System.out.println("动物都可以跑！");
    }
}

class Cat extends Animal {
    public void sing(){
        System.out.println("我们一起学猫叫，一起喵喵喵！让我们一起撒个娇");
    }
}

class Cat extends Animal {
    // 声明不变，重新实现
    // 方法名称与父类全部一样，只是方法体中的功能重写了！
    @Override
    public void sing(){
        System.out.println("我们一起学猫叫，一起喵喵喵！让我们一起撒个娇");
    }
}