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Interface
1. Because Java does not support multiple inheritance, an interface can inherit only one parent class, but multiple interfaces can be implemented. The interface itself can inherit multiple interfaces.
2. The member variables in the interface are of the public static final type by default. Initialization that must be displayed.
3. All methods in the interface are public
Click to enter _ many other _java thousand ask1. What is the difference between an interface and an abstract class?In the Java language. Abstract class and interface interface are two mechanisms of abstract definition.It is the ex
; } public double area ()//calculates the rectangle size, implementing the parent class's abstract method {return this.width*this.length; } public double perimeter ()//calculates the perimeter of the rectangle, implementing the abstract method of the parent class {return (this.width+this.length) * *; } public void SetLength (double length) {this.length =
Java AbstractMap abstract class
Jdk1.8.0 _ 144: http://www.bkjia.com/softs/551512.html
The AbstractMap abstract class implements some simple and common methods, and is not difficult. However, there are two methods in this abstract
large extension, a small connotation, a small extension of specific concepts, and a large connotation.
Ii. Abstract METHODS
An abstract method is a special method: it has only declarations, but not specific implementations. The Declaration format of the abstract method is:
1
abstractvoidfun();
Abstract
multiple interfaces at the same timeWhy should I use an interface?1, to complement the single inheritance structure.2, the interface enriches the polymorphism of the object.3, interface-oriented programming (programming or architectural thinking)The goal of software development:A center, two basic points.Everything is centered on user needs,Ensure the software has good scalability and maintainabilityCohesion-poly, low-couplingCohesion: The ability of a software system to accomplish a task indep
subclass, the other is handed over to the local operating system. If it happens at the same time, it is tantamount to handing over the implementation to the subclass and handing the implementation to the local operating system, who is going to implement the specific method?2, interface is a special kind of abstract class, the method in the interface is all abstract
Java interface and abstract class small notes@author IxenosInterface
1. The interface does not have a constructor because the interface is not instantiated2. Anonymous objects if the constructor that uses the interface also simply represents a covariant anonymous object that implements the interface3. The member variables in the interface are the public sta
;publicstaticfinal that belongs to graphic class doublepi=3.14;publiccircle (Stringname,doubler) {super (name); THIS.R =r;} The area of Publicvoidgetarea () {System.out.println (name+) is: "+pi*r*r);} The perimeter of Publicvoidgetlength () {System.out.println (name+) is: ' +2*pi*r ';}} Rectangle belongs to the one classrectextendsmyshape{intwidth;intheight;public in the graph Rect (StrIngname,intwidth,intheight) {super (name);this.width=width;this.
In object-oriented concepts, all objects are depicted by classes, but conversely, not all classes are used to depict objects, and if a class does not contain enough information to depict a specific object, such a class is an abstract class.Abstract classes In addition to the object cannot be instantiated, other functions of the
barking, but how to make sure, this method teaches abstraction.When a class describes a thing, there is not enough information to describe the thing, and this class is abstract.Abstract class Canine {abstract void sing ();//four legs, two eyes, running, jumping ...} Class D
classcircleextendsmyshape{doubler; that belongs to graphic class publicstaticfinaldoublePI=3.14; Publiccircle (stringname,doubler) {super (name); this.r=r;}publicvoid The area of Getarea () {system.out.println (name+) is: "+PI*r*r); }publicvoidgetlength () { system.out.println (name+ "perimeter is:" +2*pi*r); }}//rectangle belongs to the in the drawing A classrectextendsmyshape{intwidth;int height;publicrect (stringname,intwidth,intheight) { super
1. Definition of abstract class(1) Abstract classes provide only partial implementations of a type. cannot be instantiated.(2) The relationship between abstract class and subclass----is an application of template method pattern2. Use of
as a parameter, and the value of the parameter is the value of the variable name.3. Variable name (variable name corresponding value) {Static code block}//except 2, the enumeration class also defines an abstract method, and the code block after the variable name corresponds to an anonymous inner class that implements the abs
at the definition of Myinvoke:Inner class Myinvoke:invocationhandler { Override Fun Invoke (Proxy:any, Method:method?, Args:array if (method?. Name.equals ("Dofail")) { LOG.I (TAG, "Dofail") }else if (method?). Name.equals ("DOSUCC")) { LOG.I (TAG, "DOSUCC") } }Last run, look at the result:I/testlib:mytest Start executingI/mainactivity:dofailI/mainactivity:dosucc2. Instance
Abstract classes are often used to characterize the abstract concepts we derive in the analysis and design of the problem domain, as an abstraction of a series of concrete concepts that look different, but are essentially the same, and we cannot instantiate them (not get a concrete one) so they are called abstractions. For example: We want to describe "fruit", it is an abstraction, it has quality, volume an
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