Home 类库下载 java类库 java interface

java interface

Nov 02, 2016 pm 02:57 PM
java

Sun Company feels that the abstract class of C++ is not good and does not strictly control it. Therefore, Sun upgraded abstract classes to interfaces. Abstract classes are rarely used in Java. All declarations use interfaces to implement them.

  Interface (interface) There is only a single inheritance in Java, but multiple interfaces can be implemented. There is a saying that everything is an interface. If you want to make a very good program in Java, you must have an interface. Only with interfaces can you achieve scalability.

 Interface rules:

 1. All methods in the interface are method declarations

 2. The properties in the interface are constant properties

 3. Interfaces can be inherited from each other

 4. Interfaces cannot inherit from classes

 5. Interfaces cannot inherit abstract classes

 6. Interfaces cannot instantiate objects either

 7. All methods and properties are public

As shown in Figure 8.9:

java interface

Figure 8.9

Interfaces can be inherited as shown in Figure 8.91:

java interface

Figure 8.91

This attribute is actually a constant , regardless of whether you add the constant keyword or not, the final result is actually a constant, and the attributes of the interface are all constants.

  Interfaces cannot inherit from classes, as shown in Figure 8.92:

java interface

Figure 8.92

  Interfaces cannot inherit abstract classes, as shown in Figure 8.93:

java interface

  Figure 8.93

  The charm of interfaces:

 l When doing programming, everything must be an object

 l When doing architecture and design, everything must be an interface and programmed for parent classes

 Although interfaces have no functional implementation and only have the functions of methods, they are used in many places. Interfaces will not affect the functionality of your program, but they will affect the architecture and design of your program. We should regard everything in real life as an interface, and use interfaces to do everything when programming. If a system is full of interfaces, then the system will be very powerful. When building a system, extract all functions out of the interface, and then write an implementation class to implement this interface. Everything is an interface, which means treating everything in real life as an interface. Then the architecture of your program can be very good and very strong.

Sun is very smart. For example, if Java wants to connect to a database, it must implement some code to operate the database. Sending someone to connect to his database won't work. The database is a product that will definitely be upgraded, and the database is owned by the database company. Only the database company knows the advantages of the database, so Sun is very passive. Then Sun Company came up with a way, which is to apply all the functions of connecting to the database as interfaces, and then convene the database company to attend the press conference to let the database implement Sun Company's interface. This is the charm of interfaces. Sun stipulates the plan and then lets others implement it. As shown in Figure 8.94:

java interface

Figure 8.94

After declaring an interface, you must program for the interface. If you declare an interface but do not use it, you will not know what the use of the interface is in the future.


Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

Repo: How To Revive Teammates
1 months ago By 尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
1 months ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Square Root in Java Square Root in Java Aug 30, 2024 pm 04:26 PM

Guide to Square Root in Java. Here we discuss how Square Root works in Java with example and its code implementation respectively.

Perfect Number in Java Perfect Number in Java Aug 30, 2024 pm 04:28 PM

Guide to Perfect Number in Java. Here we discuss the Definition, How to check Perfect number in Java?, examples with code implementation.

Random Number Generator in Java Random Number Generator in Java Aug 30, 2024 pm 04:27 PM

Guide to Random Number Generator in Java. Here we discuss Functions in Java with examples and two different Generators with ther examples.

Weka in Java Weka in Java Aug 30, 2024 pm 04:28 PM

Guide to Weka in Java. Here we discuss the Introduction, how to use weka java, the type of platform, and advantages with examples.

Armstrong Number in Java Armstrong Number in Java Aug 30, 2024 pm 04:26 PM

Guide to the Armstrong Number in Java. Here we discuss an introduction to Armstrong's number in java along with some of the code.

Smith Number in Java Smith Number in Java Aug 30, 2024 pm 04:28 PM

Guide to Smith Number in Java. Here we discuss the Definition, How to check smith number in Java? example with code implementation.

Java Spring Interview Questions Java Spring Interview Questions Aug 30, 2024 pm 04:29 PM

In this article, we have kept the most asked Java Spring Interview Questions with their detailed answers. So that you can crack the interview.

Break or return from Java 8 stream forEach? Break or return from Java 8 stream forEach? Feb 07, 2025 pm 12:09 PM

Java 8 introduces the Stream API, providing a powerful and expressive way to process data collections. However, a common question when using Stream is: How to break or return from a forEach operation? Traditional loops allow for early interruption or return, but Stream's forEach method does not directly support this method. This article will explain the reasons and explore alternative methods for implementing premature termination in Stream processing systems. Further reading: Java Stream API improvements Understand Stream forEach The forEach method is a terminal operation that performs one operation on each element in the Stream. Its design intention is

See all articles