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Java Packages / API

Java is a popular programming language that is widely used for developing various applications. It is an object-oriented language that provides a rich set of features and functionalities. One of the key features of Java is its support for packages and APIs.

Introduction of Java Packages / API

Java packages are a way of organizing related classes and interfaces into a single unit. A package is a collection of related classes and interfaces that are grouped together for easy management and maintenance. Java packages provide a way to organize code into logical units, making it easier to manage and reuse code.

Java API (Application Programming Interface) is a set of classes and interfaces that provide a way to interact with the Java platform. The Java API provides a rich set of functionalities that can be used to develop various types of applications. The Java API is divided into different packages, each of which provides a specific set of functionalities.

Brief Explanation about Java Packages / API

Java packages provide a way to organize code into logical units. A package can contain classes, interfaces, sub-packages, and other resources. Packages are used to avoid naming conflicts and to provide a clear structure for the code. Java packages are hierarchical, which means that a package can contain sub-packages, and a sub-package can contain further sub-packages.

Java API provides a set of classes and interfaces that can be used to interact with the Java platform. The Java API is divided into different packages, each of which provides a specific set of functionalities. Some of the commonly used packages in Java API include:

  • java.lang - provides fundamental classes and interfaces that are used throughout the Java API
  • java.util - provides classes and interfaces for working with collections, dates, and times
  • java.io - provides classes and interfaces for working with input and output streams
  • java.net - provides classes and interfaces for working with network connections
  • java.awt - provides classes and interfaces for creating graphical user interfaces
  • javax.swing - provides classes and interfaces for creating advanced graphical user interfaces

Here are some examples of how to use Java packages and API:

Example 1: Using java.util package


import java.util.ArrayList;

public class Example {
  public static void main(String[] args) {
    ArrayList list = new ArrayList();
    list.add("Java");
    list.add("Python");
    list.add("C++");
    System.out.println(list);
  }
}

In this example, we are using the java.util package to create an ArrayList object. The ArrayList class is part of the java.util package and provides a way to store and manipulate a collection of objects.

Example 2: Using java.net package


import java.net.URL;
import java.net.HttpURLConnection;

public class Example {
  public static void main(String[] args) throws Exception {
    URL url = new URL("https://www.example.com");
    HttpURLConnection con = (HttpURLConnection) url.openConnection();
    con.setRequestMethod("GET");
    int status = con.getResponseCode();
    System.out.println(status);
  }
}

In this example, we are using the java.net package to create a URL object and establish a connection to a web server. The HttpURLConnection class is part of the java.net package and provides a way to send and receive HTTP requests and responses.

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