面向对象继承中的案例.docx

1、面向对象继承中的案例面向对象-继承中的案例 =案例一=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 setA

2、ge(int age) this.age = age; class Student extends Person class Test public static void main(String args) Student s =new Student(); s.setName(zx); s.setAge(18); System.out.println(s.getName()+=+s.getAge(); 注意：此处调用的是默认的构造参数=案例二=class Person private String name; private int age; public Person() public

3、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; class Student extends Person class Test public static void main(String ar

4、gs) Student s =new Student(zx,18); System.out.println(s.getName()+=+s.getAge(); 结果：符号： 构造函数 Student(java.lang.String,int)位置： 类 Student Student s =new Student(zx,18);注意：要想使用带参构造，要在子类中添加带参数的构造方法！=案例三=class Person private String name; private int age; public Person() public Person(String name ,int age)

5、 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; class Student extends Person public Student () public Student (String name ,int age) this.name = name

6、; this.age = age; class Test public static void main(String args) Student s =new Student(zx,18); System.out.println(s.getName()+=+s.getAge(); 结果：Test.java:26: name 可以在 Person 中访问 private this.name = name; Test.java:27: age 可以在 Person 中访问 private this.age = age; 注意：这样写是不对的，父类中的变量是私有的没有访问权限！=案例四=class

7、 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; clas

8、s Student extends Person public Student () public Student (String name ,int age) class Test public static void main(String args) Student s =new Student(zx,18); System.out.println(s.getName()+=+s.getAge(); 结果：null=0注意：带参数的构造方法，方法体不写也是有问题的=正确案例=/在有参构造方法里，调用父类的有参构造方法！class Person private String name; p

9、rivate 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; class Student extends Person public Student () public Student (String name ,int age) super(name,age); class Test public static void main(String args) Student s =new Student(zx,18); System.out.println(s.getName()+=+s.getAge(); 结果：zx=18