JDK in Java Last Updated : 03 Jan, 2025 Comments Improve Suggest changes Like Article Like Report The Java Development Kit (JDK) is a cross-platformed software development environment that offers a collection of tools and libraries necessary for developing Java-based software applications and applets. It is a core package used in Java, along with the JVM (Java Virtual Machine) and the JRE (Java Runtime Environment). Beginners often get confused with JRE and JDK, if you are only interested in running Java programs on your machine then you can easily do it using Java Runtime Environment. However, if you would like to develop a Java-based software application then along with JRE you may need some additional necessary tools, which is called JDK.JDK=JRE+Development Tools The Java Development Kit is an implementation of one of the Java Platform:Standard Edition (Java SE),Java Enterprise Edition (Java EE),Micro Edition (Java ME),Contents of JDKThe JDK has a private Java Virtual Machine (JVM) and a few other resources necessary for the development of a Java Application. JDK contains:Java Runtime Environment (JRE),An interpreter/loader (Java),A compiler (javac),An archiver (jar) and many more.The Java Runtime Environment in JDK is usually called Private Runtime because it is separated from the regular JRE and has extra content. The Private Runtime in JDK contains a JVM and all the class libraries present in the production environment, as well as additional libraries useful to developers, e.g, internationalization libraries and the IDL libraries.Most Popular JDKs:Oracle JDK: the most popular JDK and the main distributor of Java11,OpenJDK: Ready for use: JDK 15, JDK 14, and JMC,Azul Systems Zing: efficient and low latency JDK for Linux os,Azul Systems: based Zulu brand for Linux, Windows, Mac OS X,IBM J9 JDK: for AIX, Linux, Windows, and many other OS,Amazon Corretto: the newest option with the no-cost build of OpenJDK and long-term support.Set-Up:Setting up JDK in your development environment is super easy, just follow the below simple steps. Installation of JDKGo to this Oracle's official Download Page through this linkSelect the latest JDK version and click Download and add it to your classpath.Just check the JDK software is installed or not on your computer at the correct location, for example, at C:\Program Files\Java\jdk11.0.9.Set JAVA_HOME for Windows:Right-click My Computer and select Properties.Go to the Advanced tab and select Environment Variables, and then edit JAVA_HOME to point to the exact location where your JDK software is stored, for example, C:\Program Files\Java\jdk11.0.9 is the default location in windows.Java maintains backward compatibility, so don't worry just download the latest release and you will get all the old and many new features. After Installing the JDK and JRE adds the java command to your command line. You can verify this through the command prompt by the java -version command. In some cases, you need to restart your system after installing the JDK.JDK VersionCompile and Run Java Code using JDK:You can use the JDK compiler to convert your Java text file into an executable program. Your Java text segment is converted into bytecode after compilation which carries the .class extension.First, create a Java text file and save it using a name. Here we are saving the file as Hello.java. Java class Hello{ public static void main (String[] args) { System.out.println("Hello Geek!"); } } After that just simply use the javac command, which is used for the compilation purpose in Java. Please don't forget to provide the full path of your java text file to the command line else you will get an error as "The system cannot find the path specified", Your command should be similar to the given below example where Hello is the file name and the full path to the file is specified before the file name. The path and javac.exe should be inside the quotes."C:\Program Files\Java\jdk-11.0.9\bin\javac.exe" Hello.javaYou can notice now that the Hello.class file is being created in the same directory as Hello.java. Now you can run your code by simply using the java Hello command, which will give you the desired result according to your code. Please remember that you don't have to include the .class to run your code.C:\Users\Pinaki\Documents>java Hello(Output:) Hello Geek!The Jar component:JDK contains many useful tools and among them, the most popular after javac is the jar tool. The jar file is nothing but a full pack of Java classes. After creating the .class files, you can put them together in a .jar, which compresses and structures them in a predictable fashion. Now, let's convert our Hello.class to a jar file.Before proceeding, please note that you should be in the same directory where the Hello.java file was saved. Now type the command given below in the command line.Creating a .jar fileC:\Users\Pinaki\Documents>"c:\Program Files\Java\jdk-11.0.9\bin\jar.exe" --create --file Hello.jar Hello.classNow you can notice that Hello.jar file had been created in the same directory using Hello.class file and jar.exe. You can use the jar file by adding it to your classpath and executing the program inside it. Here the -cp stands for classpath which helps to add the jar to the same classpath.Executing the .jar filejava -cp hello_world.jar hello_worldImportant Components of JDKBelow there is a comprehensive list of mostly used components of Jdk which are very useful during the development of a java application.ComponentUsejavac Java compiler converts source code into Java bytecodejava The loader of the java apps.javap Class file disassembler,javadoc Documentation generator,jar Java Archiver helps manage JAR files.appletviewer Debugging of Java applets without a web browser,xjc Accepts an XML schema and generates Java classes,apt Annotation-processing tool,jdb Debugger,jmc Java Mission Control,JConsole Monitoring and Management Console,pack200 JAR compression tool,extcheck Utility tool to detects JAR file conflicts,idlj IDL-to-Java compiler,keytool The keystore manipulating tool,jstatd jstat daemon (experimental)jstat JVM statistics monitoring tool jshell jshell introduced in java 9.jstack Prints Java stack traces(experimental)jrunscript Java command-line script shell.jhat Java Heap Analysis Tool (experimental)jpackage Generate self-contained application bundles.javaws Web Start launcher for JNLP applications,javah C header and stub generator,jarsigner jar signing and verification tooljinfoconfiguration information(experimental)javafxpackagerPackage and sign JavaFX applications Comment More infoAdvertise with us Next Article Differences Between JDK, JRE and JVM P PinakiBanerjee0 Follow Improve Article Tags : Java Practice Tags : Java Similar Reads Java Tutorial Java is a high-level, object-oriented programming language used to build web apps, mobile applications, and enterprise software systems. 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In Java, String objects are immutable, which simply means once created, their values can not be changed. In Java, String, StringBuilder, and StringBuffer are used for handling strings. The main difference is:String: Immutable, meaning its value cannot be changed 6 min read Java OOPs ConceptsJava OOP(Object Oriented Programming) ConceptsJava Object-Oriented Programming (OOPs) is a fundamental concept in Java that every developer must understand. It allows developers to structure code using classes and objects, making it more modular, reusable, and scalable.The core idea of OOPs is to bind data and the functions that operate on it, 13 min read Classes and Objects in JavaIn Java, classes and objects are basic concepts of Object Oriented Programming (OOPs) that are used to represent real-world concepts and entities. The class represents a group of objects having similar properties and behavior, or in other words, we can say that a class is a blueprint for objects, wh 11 min read Java ConstructorsIn Java, constructors play an important role in object creation. A constructor is a special block of code that is called when an object is created. Its main job is to initialize the object, to set up its internal state, or to assign default values to its attributes. This process happens automaticall 10 min read Object Class in JavaObject class in Java is present in java.lang package. Every class in Java is directly or indirectly derived from the Object class. If a class does not extend any other class then it is a direct child class of the Java Object class and if it extends another class then it is indirectly derived. The Ob 7 min read Abstraction in JavaAbstraction in Java is the process of hiding the implementation details and only showing the essential details or features to the user. 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The subclass method must match the paren 15 min read Java PackagesPackages in Java are a mechanism that encapsulates a group of classes, sub-packages, and interfaces. Packages are used for: Prevent naming conflicts by allowing classes with the same name to exist in different packages, like college.staff.cse.Employee and college.staff.ee.Employee.They make it easie 8 min read Java InterfacesJava InterfaceAn Interface in Java programming language is defined as an abstract type used to specify the behaviour of a class. An interface in Java is a blueprint of a behaviour. A Java interface contains static constants and abstract methods. Key Properties of Interface:The interface in Java is a mechanism to 12 min read Interfaces and Inheritance in JavaJava supports inheritance and interfaces, which are important concepts for building reusable code. A class can extend another class and can implement one and more than one Java interface. 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It is used to store the ordered collections of elements. In a Java List, we can organize and manage the data sequentially. Key Features:Maintained the order of elements in which they are added.Allows 15+ min read ArrayList in JavaJava ArrayList is a part of the collections framework and it is a class of java.util package. It provides us with dynamic-sized arrays in Java. The main advantage of ArrayList is that, unlike normal arrays, we don't need to mention the size when creating ArrayList. It automatically adjusts its capac 9 min read Vector Class in JavaThe Vector class in Java implements a growable array of objects. Vectors were legacy classes, but now it is fully compatible with collections. It comes under java.util package and implement the List interface.Key Features of Vector:It expands as elements are added.Vector class is synchronized in nat 12 min read LinkedList in JavaLinked List is a part of the Collection framework present in java.util package. This class is an implementation of the LinkedList data structure, which is a linear data structure where the elements are not stored in contiguous locations, and every element is a separate object with a data part and an 12 min read Stack Class in JavaThe Java Collection framework provides a Stack class, which implements a Stack data structure. The class is based on the basic principle of LIFO (last-in-first-out). Besides the basic push and pop operations, the class also provides three more functions, such as empty, search, and peek. The Stack cl 11 min read Set in JavaThe Set Interface is present in java.util package and extends the Collection interface. It is an unordered collection of objects in which duplicate values cannot be stored. It is an interface that implements the mathematical set. This interface adds a feature that restricts the insertion of duplicat 14 min read Java HashSetHashSet in Java implements the Set interface of Collections Framework. It is used to store the unique elements and it doesn't maintain any specific order of elements. Can store the Null values.Uses HashMap (implementation of hash table data structure) internally.Also implements Serializable and Clon 12 min read TreeSet in JavaTreeSet is one of the most important implementations of the SortedSet interface in Java that uses a Tree(red - black tree) for storage. The ordering of the elements is maintained by a set using their natural ordering whether or not an explicit comparator is provided. This must be consistent with equ 13 min read Java LinkedHashSetLinkedHashSet in Java implements the Set interface of the Collection Framework. It combines the functionality of a HashSet with a LinkedList to maintain the insertion order of elements. Stores unique elements only.Maintains insertion order.Provides faster iteration compared to HashSet.Allows null el 8 min read Queue Interface In JavaThe Queue Interface is a part of java.util package and extends the Collection interface. It stores and processes the data in order means elements are inserted at the end and removed from the front. Key Features:Most implementations, like PriorityQueue, do not allow null elements.Implementation Class 11 min read PriorityQueue in JavaThe PriorityQueue class in Java is part of the java.util package. It implements a priority heap-based queue that processes elements based on their priority rather than the FIFO (First-In-First-Out) concept of a Queue.Key Points:The PriorityQueue is based on the Priority Heap. The elements of the pri 9 min read Deque Interface in JavaDeque Interface present in java.util package is a subtype of the queue interface. 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It stores key-value pairs while maintaining the insertion order of the entries. It maintains the order in which elements are added.Stores unique key-value pairs.Maintains insertion order.Allows one null key and multiple 7 min read Hashtable in JavaHashtable class, introduced as part of the Java Collections framework, implements a hash table that maps keys to values. Any non-null object can be used as a key or as a value. To successfully store and retrieve objects from a hashtable, the objects used as keys must implement the hashCode method an 12 min read Java Dictionary ClassDictionary class in Java is an abstract class that represents a collection of key-value pairs, where keys are unique and used to access the values. It was part of the Java Collections Framework and it was introduced in Java 1.0 but has been largely replaced by the Map interface since Java 1.2.Stores 5 min read SortedSet Interface in Java with ExamplesThe SortedSet interface is present in java.util package extends the Set interface present in the collection framework. It is an interface that implements the mathematical set. This interface contains the methods inherited from the Set interface and adds a feature that stores all the elements in this 8 min read Java Comparator InterfaceThe Comparator interface in Java is used to sort the objects of user-defined classes. The Comparator interface is present in java.util package. This interface allows us to define custom comparison logic outside of the class for which instances we want to sort. The comparator interface is useful when 7 min read Java Comparable InterfaceThe Comparable interface in Java is used to define the natural ordering of objects for a user-defined class. It is part of the java.lang package and it provides a compareTo() method to compare instances of the class. A class has to implement a Comparable interface to define its natural ordering.Exam 4 min read Java Comparable vs ComparatorIn Java, both Comparable and Comparator interfaces are used for sorting objects. The main difference between Comparable and Comparator is:Comparable: It is used to define the natural ordering of the objects within the class.Comparator: It is used to define custom sorting logic externally.Difference 5 min read Java IteratorAn Iterator in Java is an interface used to traverse elements in a Collection sequentially. It provides methods like hasNext(), next(), and remove() to loop through collections and perform manipulation. An Iterator is a part of the Java Collection Framework, and we can use it with collections like A 6 min read Like