abstract class vs interface java

Method Abstract_func (): Class B extends a{}; Then the program will appear with the following error: Fatal Error:class B contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (A::abstract_func) 5. If b implements the abstract method Abstract_func (), then the access cont

class is defined and the purpose is to achieve polymorphism, then I think it is reasonable to refer to this abstract class as an "interface". But is it unreasonable to use abstract class to realize polymorphism? Discussed in the

This article mainly introduces the php interface and abstract class examples, and explains in detail. if you need them, you can refer to section 1. abstract class 1. abstract class ref

Only single inheritance between classes and classesThere can be many implementations between the class and the interface;Multiple inheritance between interface and interface; 　 Statement Variable Method Relationships with interfaces Relationship

}9 }Ten classGoodstudentextendsstudent{ One //the abstract method must be implemented, otherwise the class is still an abstract class A Public voidStudy () { -SYSTEM.OUT.PRINTLN ("Good students do not study"); - } the } - Public classTest { - Public Static voidMain (string[] args) { -Goodstudent

Features of the Java abstract class:* Abstract classes cannot be instantiated* Subclass inherits Abstract class and instantiates subclass* Subclasses inherit abstract classes has penny

public levelAbstract classes can contain fields, but interfaces cannot,Abstract classes can inherit interfaces, but interfaces cannot inherit abstract classes.Abstract class members can have specific implementations, but interfaces cannot.The abstract subclass can selectively implement the

order of the object with the specified object. If the object is smaller than, equal to, or greater than the specified object, a negative integer, zero, or positive integer is returned.We strongly recommend (X. compareto (y) = 0) = (X. Equals (y), but not strictly.2.4 comparator Interface Comparator is located under the java. util package, while comparable is located under the

An abstract class implementation interface can not implement all the methods of the interface A non-abstract class implementation interface must implement all methods. When an

First, exhausting and abstract methods1. Abstract methods in abstract classes must be implemented by the quilt class unless the subclass is also abstract.2. Abstract class cannot be ins

their subclasses (function bodies should be available, even if {} is empty ), java designers may consider the flexibility of abstract methods. each subclass can implement abstract methods as needed. // The abstract class must be instantiated to call the method

?OKthere is only one purpose, that is, to not allow other classes to create objects of this class, to complete the child classB: Face question 2Abstract cannot coexist with which keywordsStatic, Final, private Explain:Abstract and staticThere is no method body for the method that is modified by abstractThe method to be modified by static is to use the class name. Called, but the

1. Introduction In my previous post titled "who is the abstract class and interface?", I discussed with my colleague Guan Wei and got the attention of many friends, because it is not a systematic theory, this makes it inconvenient for you to understand.I think it is also necessary to make a summary of the systemic theory of this topic, so this article is coming s

When writing a program, I often get tangled up, whether an abstract object should be defined as an abstract class or an interface (Interface)? The two are very similar, even can be replaced with each other, difficult to choose. This question has been asked many times on Stac

First, you must understand what is an abstract class:I. concept:In the concept of object-oriented, we know that all objects are depicted through classes, but this is not the case.Not all classes are used to depict objects. If a class does not contain enough information to depict a specific object, such classes are abstract classes.For example, if we develop a gra

Document directory Author: Anytao Source: Forum Organizing Editor: Ark 1. IntroductionIn my previous post titled "who is the abstract class and interface?", I discussed with my colleague Guan Wei and got the attention of many friends, because it is not a systematic theory, therefore, it is inconvenient for everyone to understand. At the same time, I think it

Source: http://www.cnblogs.com/gxinliug/archive/2011/04/27/2031246.html Abstract class and interface are two mechanisms supported for the definition of abstract classes in Java. It is precisely because of the existence of these two mechanisms that give

is abstraction, there is non-abstract(4) Practice of abstract classesA: Cat and dog case exerciseB: Teacher Case ExercisesC: Student Case ExerciseD: Employee Case Exercise(5) Some small problems of abstract classA: Abstract class has a construction method, can not be instan

method, G, but since it does not provide an implementation of F, B must also be declared as an abstract class. Class C OverridesF, and provide a concrete implementation. Because there are no abstract members in C, it is possible (but not necessary) to declare C as a non-abstract