标签：Java methods 子类类图接口 OOP class

Lecture 1：OOP and UML Class DiagramsOOP with Java

OOP 和 UML 类图 OOP 与 Java

Object-Oriented Programming 面向对象编程

Superclass and subclass
超类和子类

Abstraction
– Modelling attributes and behaviors of real objects, in specific contexts
抽象——对真实对象的属性和行为进行建模，具体来说

At the top level
在顶层
– public, or package-private (no explicit modifier)
公共或包私有（无显式修饰符）
At the member level
在成员级别
– public, private, protected, or package-private (no explicit modifier)
public、private、protected 或 package-private（无显式修饰符）

Classes can be derived from other classes, inheriting fields and methods
类可以从其他类派生，继承字段和方法
Definitions
定义
– Subclass (derived class/extended class/child class)
– Superclass (base class/parent class)
– 子类（派生类/扩展类/子类）
– 超类（基类/父类）
Every class has one and only one direct superclass (single inheritance)
每个类都有一个且仅有一个直接超类（单继承）
– Excepting Object, which has no superclass
除了Object，它没有超类
A subclass inherits all the members (fields, methods, and nested classes) from its superclass
子类继承其超类的所有成员（字段、方法和嵌套类）

Use the inherited members as is, replace them, hide them, or supplement them
按原样使用继承的成员、替换它们、隐藏它们或补充它们

Declare a field in the subclass with the same name as the one in the superclass, thus hiding it (NOT recommended)
– 在子类中声明一个与超类中的字段同名的字段，从而隐藏它（不推荐）
Write a new instance method in the subclass that has the same signature as the one in the superclass, thus overriding it
– 在子类中编写一个新的实例方法，其签名与超类中的字段相同，从而覆盖它
Write a new static method in the subclass that has the same signature as the one in the superclass, thus hiding it
–在子类中编写一个新的静态方法，该方法与超类中的静态方法具有相同的签名，从而隐藏它
Write a subclass constructor that invokes the constructor of the superclass
– 编写一个调用超类构造函数的子类构造函数

How about private members in a superclass?

An abstract class is a class declared abstract: it may or may not include abstract methods
抽象类是声明为抽象的类：它可能包含也可能不包含抽象方法
An abstract method is a method declared without an implementation
抽象方法是声明但没有实现的方法
Final methods and classes
最终方法和类
Methods called from constructors should generally be declared final
– 从构造函数调用的方法通常应声明为final

Interfaces are contracts
接口是契约
A reference type, containing only constants, method signatures,default methods, static methods, and nested types
引用类型，仅包含常量、方法签名、默认方法、静态方法和嵌套类型
Cannot be instantiated
无法实例化
– They can only be implemented by classes or extended by other interfaces
– 它们只能由类实现或由其他接口扩展
Consisting of modifiers, keyword, interface name, a comma-separated list of parent interfaces (if any), and the interface body
由修饰符、关键字、接口名称、以逗号分隔的父接口列表（如果有）和接口主体组成
Interface body can contain abstract methods, default methods,and static methods
接口体可以包含抽象方法、默认方法和静态方法

Include an implements clause in the class declaration
在类声明中包含 implements 子句
– Your class can implement more than one interface
– 你的类可以实现多个接口
If you define a reference variable whose type is an interface,any object you assign to it must be an instance of a class that implements the interface
如果定义类型为接口的引用变量，则分配给它的任何对象都必须是实现该接口的类的实例

标签：Java,methods,子类,类图,接口,OOP,class
From： https://www.cnblogs.com/Mephostopheles/p/18411950