What is a class library in java

Java officially provides developers with many powerful classes. These classes are placed in various packages and released together with the JDK, called For Java class library.

For example, I wrote a class that can obtain various hardware information of the computer. It is very powerful and stable. If your project also needs such a function, then you no longer need to write the code yourself. Just use my class directly.

However, my class code is very complicated and it is not realistic for you to read the code. Moreover, I don’t want you to see my code and I want to protect my copyright. What should I do?

I can compile my class first and attach it with a document telling you how to use my class and what methods and properties it has. You only need to follow the instructions in the document to call it, and it will be no problem. It saves money. It saves you time reading the code and protects my copyright. For example, how to obtain CPU information:

getCpuInfo(int cpuType);

Introduction to packages in Java class library:

The package starting with java.* is the core package of Java, which will be used by all programs classes in these packages.

The ones starting with javax.* are extension packages, and x means extension, which means extension. Although javax.* is an optimization and extension of java.*, because javax.* is used more and more, many programs rely on javax.*, so javax.* is also part of the core and is also released with the JDK. .

The packages starting with org.* are packages released by various institutions or organizations. Because these organizations are very influential and their code quality is very high, some of the commonly used classes developed by them are also released together with the JDK. .

In terms of naming packages, in order to prevent duplicate names, there is a convention: everyone names the packages they develop starting with the inverted form of their own domain name. For example, the package released by Baidu will start with com.baidu Starting with .*, the package released by the w3c organization will start with org.w3c.*, and the package released by Wei Xueyuan will start with net.weixueyuan.*...

The domain name suffix of the organization is generally org, and the company's domain name suffix The domain name suffix is ​​generally com. It can be considered that packages starting with org.* are packages released by non-profit organizations. They are generally open source and can be used in your own products for free without considering infringement issues. Packages starting with com.* Packages are often released by for-profit companies and may have copyright issues, so be careful when using them.

Recommended tutorial: Getting started with java development

The above is the detailed content of What is a class library in java. For more information, please follow other related articles on the PHP Chinese website!