黑马程序员学JavaDay2(面向对象编程：继承)

1.继承及其特点

2.权限修饰符

3.单继承

4.Object类

5.方法重写

    @Override
    public String toString() {
        return "Student [age=" + age + ", name=" + name + ", grade=" + grade + "]";
    }

6.在子类中访问其他成员

7.子类构造器

    public Student(int age,String name,int grade) {
        super(age,name);
        this.grade = grade;
    }

    public Student(int age,String name,int grade) {
        super(age,name);
        this.grade = grade;
    }

    public Student(int age){
        this(age,"学生名",1);
    }