JAVA面向对象高级一：继承子类方法中访问其他成员 子类构造器的特点 子类构造特点的应用场景

1.在子类方法中访问其他成员（成员变量，成员方法），就依照就近原则。

 

 

 

 

 

2.子类构造器的特点

 

package com.itheima.子类访问成员变量;

public class F {
    public F(String a,int b){
        System.out.println("===父类的无参构造器执行了===");
    }



}




package com.itheima.子类访问成员变量;

public class Z extends F{
    public Z(){
       super("2",2);//默认存在的
        System.out.println("===子类的无参构造器执行了===");
    }
    public Z(int z){
        super("2",2);//默认存在的
        System.out.println("===子类的无参构造器执行了===");
    }


}


package com.itheima.子类访问成员变量;

public class Test {
    public static void main(String[] args) {
    //子类构造器的特点：子类的全部的构造器，
    // 都会先调用父类的构造器，在执行自己

        //若父类无无参构造器，子类构造器则会都报错
    Z z =new Z();
    Z z1 =new Z(2);
    }

}

子类构造特点的应用场景：

 

package com.itheima.子类访问成员变量;

public class Test {
    public static void main(String[] args) {
    Teacher teacher=new Teacher("lisi",36,"java");
    }

}
class Teacher extends  People{
    private String skill;
    public Teacher(String name,int age,String skill){
        super(name,age);
        this.skill=skill;

    }

    public String getSkill() {
        return skill;
    }

    public void setSkill(String skill) {
        this.skill = skill;
    }
}

class People{
    private String name;
    private int age;

    public People() {
    }

    public People(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;
    }
}

 

 

 

this（）调用兄弟构造器：

 

任意类的构造器中，是可以通过this（..）去调用该类的其他构造器的     this()与super(）不能同时出现在一个类里

package com.itheima.子类访问成员变量;

public class Test {
    public static void main(String[] args) {
        Student student=new Student("lisi",26,"zjilidun");
        Student student1=new Student("lisi",26);
    }
}

class Student{
    private String name;
    private int age;
    private String schoolName;
    public Student(String name,int age) {
        this(name,age,"黑马程序员");
    }

    public Student() {
    }

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

    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 getSchoolName() {
        return schoolName;
    }

    public void setSchoolName(String schoolName) {
        this.schoolName = schoolName;
    }
}

 

 

 

总结：