Chapter 4: JDKs and Libraries in Java

JDK stands for Java Development Kit. It is a set of packages and classes which contains basic "functions" like String functions, Math functions in java.

There is a concept of Packages in java. Just like a folder, a package can be used to store classes of the same type having different functions. 

Syntax for accessing a package in java: import <package1>.<package2>.<classname>;

Example: import java.io.DataInputStream;

This will import the DataInputStream class into your program for you to use. This means there is a default folder called java with a folder called io in it which contains i/o (input/output) related classes i.e. here DataInputStream

A dot "." is used to access folders/packages or classes inside a folder/package.

An "*" represents that all classes in the following package have to be imported.

A package is always imported before defining a class.

IN SCHOOLS WE USE JDK 1.5, LATEST JDK 18 HAS BEEN RELEASED IN 2022

In JDK 1.5, we have some major packages which are:

java.lang

java.io

java.util

java.text

java.applet

java.net

java.math

JavaDocs about this JDK 1.5 are listed on the official website:

 https://docs.oracle.com/javase/1.5.0/docs/api/

Library in java refers to a set of packages and classes such that the Library performs different functions.

Java library performs various basic functions in java.

NOTE: YOU CAN ALWAYS REFER TO JAVA DOCS FOR MORE INFORMATION

https://docs.oracle.com/javase/1.5.0/docs/api/

Happy Learning! 👋