What is Java library

A Java library is a byte code based on virtual-machine. It helps to encode the classes within the library. Here, a library is a collection of different classes. Java Class Library is a pack of dynamic libraries that are loadable at the time of running Java applications. There are many different and some important collection of Java class library which can be discussed further.

There are thousands of libraries which gives free usage. The following are the few Java libraries. 

1. Java Standard libraries: These libraries are very powerful to use but are most underrated libraries. These can be used for any work like sending and receiving HTTP requests to manage different type of applications. Some other third party libraries are also available like GSON and Guava. Some of these important libraries are java.lang, java.io, java.math, java.util, etc.  
2. Apache commons: This is the best multipurpose Java library. It is like Java standard library. It is almost useful for every work. It helps to work with typical files like .zip, .tar, .rar, etc. It helps in creating and modifying spreadsheets. It can be useful for some other functions like image processing, FTP, VFS, IO, logging, ZIP, etc. Other workings like emailing, statistics, HTTP request, etc. Are also get support from this library.
3. Hibernate: This library features are used to map Java classes with relational databases like MySQL. It provides an easy abstract of data in relational database.  It uses JDBC for its implementation.
4. JHipster: It is a development platform to create and deploy different applications and services like Spring Boot and Angular web applications. It also includes Spring microservices.
5. Maven: It is software project management tool. It can manage all project configurations and documentation using a single pom.xml file.
6. Guava: It is also known as Google Core libraries for Java. It is an extension of basic Java collections.
7. Google-GSON: This is very helpful library to convert Java objects to JSON. This is helpful in developing mobile applications along with creating REST APIs. These helps to convert Java objects into JSON files. 
8. JUnit: It is a free Java framework useful for writing unit tests. It provides functional support to the repeatable tests. 
9. Mockito: This library enables us to create and write mock tests easily with simple codes. Writing better and great tests is not an easy task.

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Java library example

Other than the above there are some open-source libraries available such that Logging libraries, JSON parsing libraries, general purpose libraries, Unit test libraries, HTTP libraries, XML parsing libraries, excel reading libraries, messaging libraries, bytecode libraries. These are the various examples of Java library.

These libraries serve different purposes for the developers of Java. It also helps the people associated with Java and its different libraries.  

Logging libraries: These libraries are common to use in every project. They play an important role in server-side applications. These logs can be placed to look into the activity going on applications. Java developers should be aware of the advantages and disadvantages of logging libraries.

General-purpose libraries: There are some general purpose good libraries available to Java programmers such as Apache Commons and Google Guava. These helps to simplify a lot of things in the projects.

JSON parsing libraries: It is helpful in web services. JSON is a protocol that carries information from client to the server. It is a replacement for XML which is commonly used for transferring information files. The developers should know at least one of these libraries. 

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Unit Test Libraries: These libraries help in creating and writing unit tests. These include Mockito, Powermock, JUnit, etc.

HTTP libraries: It helps in creating HTTP connection using different classes in java.net package. The Java developer must know about the HTTP client libraries.

XML parsing libraries: These libraries include JAXP, JAXB, Xerces,  Xstream, etc. Xerces 2 is the next generation framework that is fully compatible with XML parsing library features.

Messaging libraries: It is similar to the logging and database connection. It has some common features of Java applications. It offers JMS services that require separate jms.jar file. 

Bytecode libraries: These libraries helps in reading and modifying bytecodes those generated from various applications. There are few popular bytecodes in Java world such as Javaassist and Cglip Nodep. The Javaassist helps in Java bytecode manipulations.

Java library functions

Java library functions are the inbuilt functions that are present in Java library classes. It helps programmers to perform their tasks very easily. There are different functions of Java library such as java.io, java.util, java.math, java.lang, java.net, java.awt, etc. These are the different classes in Java. These are useful for various purposes.  Using these functions, developers can do any task easily. Thus, these are the most useful and standard function of Java Library. Developers can use these functions to alter the complex program situations.

Java library class advantages

• It helps to reduce the size of the classes.
• It cleans the APIs that helps to protect internal fields’ leakage.
• Useful for testing libraries other than applications.
• Helps to reuse these libraries for different projects.
• Objects and their corresponding classes compress the complex programs into small problems.
• Helps independent objects to communicate with each other.
• It gives easy to find location of each class.
• It provides easy access control.
• It also provides user friendly application experience.
• It offers multilingual support.

These are the few advantages of java class library. It helps the developers to work easily with these libraries. It makes applications and its related things smoother to use. 

Java library packages

In simple terms, Java library is a collection of different packages which contains classes and interfaces. The Java library packages are divided into two categories such as; Built-in packages, User-defined packages.

Built-in packages

The built-in packages include Java API. Java API is prewritten library class. It also includes Java development environment. This library includes the components for input management, database program, etc. To use this class or library, it needs a keyword known as import.

User-defined packages

Here, the Java library uses a file system directory to store the packages. Here package keyword is used to create a package.

For example,

└── root

  └── mypack

    └── MyPackageClass.java 

The top Java packages are as follows.

Org.apache.hadoop

Org.apache.commons

Org.apache.camel

Org.apache.http

Com.google.common

Org.pentaho

The above Java packages help the developers in various ways. They serve different purposes for different functions. Each library has different values. 

Thus, the above writings explain the importance of Java library and the different functions and uses of this library. These are the collection of different classes which helps in running Java applications smoothly. There are different Java class libraries which include various functions that help Java developers in many ways. Every developer must know about these libraries in a better way to implement the right things. It is important to learn the updates also regarding these functions to serve better in this field.

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