Java object-oriented-abstract class

Java object-oriented- abstract class

Definition: In Java, a class containing abstract methods is called an abstract class, nor can it generate objects;

Note the point :

1, the class containing an abstract method is an abstract class;

2, abstract and abstract methods are to be modified with abstract keywords;

3, the abstract method only needs to declare but does not need to implement;

4, abstract classes must inherit from the Quilt class, (if not abstract classes) must override all abstract methods in the abstract parent class;

5, abstract classes cannot be instantiated;

Let's start by defining an abstract class:

1  PackageCom.java1234.chap03.sec11;2  3 /**4 * Define an abstract class people5  * @authorUser6  *7  */8  Public Abstract classpeople {9  Ten     PrivateString name; One   A      PublicString GetName () { -         returnname; -     } the   -      Public voidsetName (String name) { -          This. Name =name; -     } +       -      Public voidsay () { +System.out.println ("My name is:" + This. GetName ()); A     } at       -     /** - * Define an abstract method occupation let subclass to concrete realization -      */ -      Public Abstract voidprofession (); -       in}

Abstract class, define a property name and method say () and then define an abstract method profession the implementation of the subclass to achieve;

Let's do a test class:

I'm trying to instantiate the following class of people:

We will see compile error, can not instantiate people class;

We define a student class, and a teacher class:

  1  package   Com.java1234.chap03.sec11;   2   3  public  class  Student extends   people{  4   5   @Override   6  public  void   profession () {  7  System.out.println (" Occupation is: Student "  8  }   9  10 } 

  1  package   Com.java1234.chap03.sec11;   2   3  public  class  Teacher extends   people{  4   5   @Override   6  public  void   profession () {  7  System.out.println (" Occupation is: Teacher "  8  }   9  10 } 

Let's do a test class:

1  PackageCom.java1234.chap03.sec11;2  3  Public classTest {4  5      Public Static voidMain (string[] args) {6          7Student student=NewStudent ();8 student.profession ();9          TenTeacher teacher=NewTeacher (); One teacher.profession (); A           -     } -}

Run output:

Occupation is: Student

Occupation is: Teacher

Java object-oriented-abstract class