Java Tutorial

Java Tutorial Java Features C++ vs Java Java History Java Hello World Java Development Kit Java Runtime Environment Java Virtual Machine Difference between JDK, JRE, and JVM Memory Areas in Java Java Operators Java Keywords Primitive Data Types Variables

Java Loops

Java Do While Loop Java While Loop Java For Loop Java Enhanced For Loop

Java Programs

Java Basic Programs Factorial Program in Java Fibonacci Series Program in Java Prime Number Program in Java Palindrome Number Program in Java Armstrong Number Program in Java Anagram Program in Java Pattern Programs in Java Calculator Program in Java Leap Year Program in Java Addition Program in Java Number Pattern Programs in Java Star Pattern Programs in Java Package Program in Java Pyramid Program in Java Sorting Program in Java String Palindrome Program in Java Even Odd Program in Java For Loop Program in Java If Else Program in Java Switch Case Program in Java GCD Program in Java LCM Program in Java Hello Program in Java Matrix Program in Java Menu Driven Program in Java Series Program in Java Client Server Program in Java Swapping Program in Java Pig Latin Program in Java Tower of Hanoi Program in Java Recursion Program in Java Matrix Multiplication Program in Java Perfect Number Program in Java Classes and Objects in Java Example Programs String Programs in Java Array Programs in Java Constructor Program in Java Inheritance Program in Java Abstract class Program in Java Interface Program in Java Encapsulation Program in Java Polymorphism Program in Java Exception Handling Program in Java Multithreading Program in Java Thread Program in Java Collection Programs in Java ArrayList Program in Java Stack Program in Java Applet Program in Java Swing Program in Java JDBC Program in Java How to run Java program in command prompt How to run Java program in Eclipse Program to find and replace characters on string in java Program to find the duplicate characters in a string Program to check whether a given character is present in a string or not Java Program to Print Permutations of String Java program to find frequency of characters in a string Java Program to remove duplicate characters in a string

Java Sorting

Sorting Algorithms in Java Merge Sort in Java Quick Sort in Java Bubble Sort in Java Insertion Sort in Java Selection Sort in Java Heap Sort in Java Radix Sort in Java Topological Sort in Java Bucket Sort in Java Counting Sort in Java

Java OOPs Concepts

OOPs - Object Oriented Programming Objects and Classes in Java Methods in Java Java Naming Conventions Constructors in Java Java this keyword Java static keyword Inheritance in Java Aggregation in Java Java super keyword Constructor Chaining and Constructor Overloading Java Polymorphism Static and Dynamic Binding in Java Java Abstraction Abstract class in Java Interface in Java Difference between Abstract class and Interface Java final keyword Packages in Java Access Modifiers in Java Java Wrapper classes Java Numbers Java Characters Java Integer Java Boolean Java Arrays Java Command Line Arguments Java strictfp Keyword Java Math

Java Strings

Java Strings Java String Methods StringBuilder in Java StringBuffer in Java Java Regular Expressions StringBuffer vs StringBuilder String vs StringBuffer String vs StringBuilder String Manipulation in Java Java String Concatenation How to Reverse a String in Java String Array in Java How to Compare Two Strings in Java How to Concatenate Two Strings in Java Why String in Immutable in Java Java.lang.NumberFormatException for Input String String Pool in Java Java Generate Random String How to take String Input in Java Java String Interview Questions

Java Exceptions

Exception Handling in Java Java try catch Java throw Java throws Difference between throw and throws Java finally Java Custom Exception Java Exception Propagation

Garbage Collection

Automatic Resource Management in Java Java Garbage Collection Java finalize() Java gc() Difference between final, finally and finalize


Multithreading in Java Process and Thread in Java Basic Terms in Multithreading Java Thread creation Thread Scheduler in Java Java Thread class DeadLock in Java

Java IO

Java IO Java Read File Java file Reader Java Buffer Reader Java file Writer Java BufferedWriter Java InputStreamReader Scanner in Java Java StringReader Java StringReader Class Java PrintWriter Java File Java Read File Line By Line Java FileInputStream Java FileOutputStream Java Create File Java Delete File Java Open File Java Read File to String Java copy file Java Read JSON file Jar File in Java Java FileNotFoundException


Java Serialization Java transient


Java Network Programming Java Socket Programming Java URL Java URLConnection HttpURLConnection in Java Java InetAddress Java DatagramSocket and Java DatagramPacket


Java AWT


Swing in Java

Java Collections

Collections in Java Java List Interface ArrayList in Java LinkedList in Java Vector in Java Stack in Java ArrayList vs LinkedList in Java ArrayList vs Vector in Java Java Set Interface HashSet in Java LinkedHashSet in Java TreeSet in Java Java Queue Interface PriorityQueue in Java ArrayDeque in Java Java Map Interface HashMap in Java LinkedHashMap in Java TreeMap in Java Dictionary in Java Hashtable in Java Properties in Java Collections class in Java Java Comparable Java Comparator Comparable vs Comparator in Java

Java Generics

Generics in Java

Java Annotations

Annotations in Java


Java JDBC Tutorial JDBC Architecture Types of JDBC Drivers JDBC vs ODBC Java Database Connectivity with MySQL Statements in java Prepared statement in Java Resultset in java Java ResultSetMetaData DatabaseMetaData in Java Callable Statement in Java Transaction Management in java Design of JDBC

Java Differences

Java vs JavaScript Python vs Java Kotlin vs Java Java vs C++ C# vs Java Java float vs double Java vs Scala Static vs Non-static in Java C vs Java int vs Integer in Java Java protected vs private Java vs Dot Net Stack vs Heap in Java Java Array vs ArrayList Java SE vs EE Difference between = = and equals ( ) in java Difference between C, C++, java

How to

How to run Java program How to set path in Java How to check the Java version in cmd How to install Java in Windows 10 How to run Java program in cmd How to add double quotes in a string in Java How to convert list to String in Java How to call a method in Java How to sort an array in Java How to iterate HashMap in Java How to write Java program How to create an array in Java How to create a package in Java How to generate random numbers in Java How to input String in Java How to create thread in Java How to find length of String in Java How to sort a string in Java How to use scanner in Java How to achieve multiple inheritance in Java How to find the length of an Array in Java How to run Java program in Eclipse How to call a function in Java How to create array of objects in Java How to create custom exception in Java How to import packages in Java How to run applet Program in Java How to take Array Input in Java How to achieve abstraction in Java How to call static method in Java How to compare characters in Java How to compare dates in Java How to create a linked list in Java How to get ASCII value of char in Java How to initialize string array in Java How to Install Java on MAC How to run java program in ubuntu How to find characters with the maximum number of times in a string java How to Set Java_home in Linux How to Split the String in Java with Delimiter How to uninstall the Java in Ubuntu How to Split String by Comma in Java How to remove special characters from String in Java How to remove last character from String in Java

Java 8 Features

Java 8 Features Lambda Expressions in Java Functional Interface in Java Streams in Java Java Base64 Encoding and Decoding Java Stringjoiner Class Parallel Arrays Sort in Java

Java 9 Features

Java 9 Tutorial Java 9 Try With Resources Java 9 Interface Private Method

Java 16

Java 16

Java 17

What is new in Java 17

Java Servlet Tutorial

Java Servlets Tutorial

Java JSP Tutorial

Java JSP Tutorial

Hibernate Tutorial

Hibernate Tutorial

Spring Tutorial

Spring Tutorial

Spring MVC Tutorial

Spring MVC Tutorial

Jenkins Tutorial

Jenkins Tutorial

Java Math Methods

Math.abs() Math.acos() Math.addExact() Math.asin() Math.atan () Math.atan2() Math.cbrt() Math.ceil() Math.copysign() Math.cos() Math.cosh() Math.decrementExact() Math.exp() Math.expm1() Math.floor() Math.floorDiv() Math.floorMod() Math.fma() Math.getExponent() Math.hypot() Math.IEEEremainder() Math.incrementExact() Math.log() Math.log10() Math.log1p() Math.max() Math.min() Math.multiplyExact() Math.multiplyFull() Math.negateExact() Math.nextAfter() Math.nextDown() Math.nextUp() Math.pow() Math.random() Math.rint() Math.round() Math.scalb() Math.signum() Math.sin() Math.sinh() Math.sqrt() Math.subtractExact() Math.tan() Math.tanh() Math.toDegrees() Math.toIntExact() Math.toRadians() Math.ulp()

Java String Methods

toCharArray() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() intern() isEmpty() join() lastIndexOf() length() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toLowerCase() toUpperCase() trim() valueOf()

Java Conversion

Java Convert String to int Java Convert int to String Java Convert String to long Java Convert long to String Java Convert String to float Java Convert float to String Java Convert String to double Java Convert double to String Java Convert String to Date Java Convert Date to String Java Convert String to Object Java Convert Object to String Java Convert String to char Java Convert char to String Java Convert int to long Java Convert long to int


Functional Interfaces in Java Singleton class in Java Awesome explanation of Strings in Java Object class in Java Static class in Java All the important string methods in Java String Handling Method in Java What are Array strings in Java Advantages and Disadvantages of Strings in Java Big Decimal class in Java Class definition in Java Char and String differences in Java Difference between String, StringBuffer and StringBuilder in java Replace character in string Java String Coding Interview Questions in Java What is String in Java? String isnullorempty in Java String Matches in Java Trim Method in String Java Bean class in Java Libraries in Java Arithmetic Operations on String in Java Convert Char array to string in java Check whether Java is installed or not How to calculate time difference in Java How to stop execution after a certain time in Java Jagged Array in Java Java ArraylistRemove() Time Complexity Java Swing Time Picker Zigzag Array in Java Array and String based questions in Java Array and String with Examples in Java Best Practices to use String Class in Java What is string in Java why it's immutable Java String Java String Inbuilt functions Java String Matches vs Contains Sum of digits in string in java Check the presence of Substring in a String in java Java import packages Interfaces and Classes in Strings in Java Maximum length of string in java Hidden classes in Java Class memory in Java public static void main string args meaning in java Reverse a String in Java String Concatenation in Java Difference between String and Char Array in Java Buffer reader to read string in Java Split String into String Array in Java Reverse a String using Collections in Java Upcasting and Downcasting in Java String Declaration in Java Method Overloading In Java Java Solid Principles Java Architecture Binary Search Java Star Program in Java Java Type Casting Java Pass-by-Reference Java Framework List Java Destructors Java Control Statements Java Byte Code Java Beans Java Identifiers Character Array in Java Java Applications Java Substring Java Session Non-primitive data types in Java Matrix Multiplication in Java JIT in Java Java Tokens Java Externalization Default Virtual Behaviour in C++ vs Java Why we use static in Java Session Tracking in Java Knapsack problem in Java Java Logo Java exception list Java Iterator Java instance variable Frugal number in Java Fork Join in Java Date time API in java Compile time vs Runtime in java Compare time in java AES 256 Encryption in Java Advanced Java skills What is advance Java? User Defined Exception in Java Upcasting in Java Tree Implementation in Java Special Operators in Java Reentrant Lock in Java Perfect Number in Java Java logger Java LinkedList vs ArrayList File Operation in Java Differences between Byte Code and Machine Code Difference between String Tokenizer and split Method in Java Difference between JIT and JVM in Java Constructor Overloading in Java Conditional operator in Java Concurrent Linked Deque in Java with Examples Command Class in Java Java Break Keyword Best Java IDE Association in Java Access specifiers in Java

Java Architecture

Java architecture is a combination of three parts they are JVM, JRE and JDK. These components will help in the functioning of the java programs. The process of code interpretation and compilation can be done with these components. Java Architecture describes the step-by-step execution and compilation of the code by the java compJava compiler step-by-step execution and compilation.

Java Architecture

The following steps can describe Java Architecture:

  • Java has both compilation and interpretation processes.
  • The compiler in java will convert the written java code to byte code.
  • After converting to byte code, the component( JVM) will convert it to machine code.
  • After that, the converted machine code is executed using the machine.

Now let us discuss the components in detail.

Components of  Java Architecture

  • Java Virtual Machine (JVM)
  • Java Runtime Environment (JRE)
  • Java Development Kit (JDK)
Java Architecture

Java Virtual Machine

Java Virtual machine main feature WORA. Write Once Run Anywhere. This feature describes that you write the code at once and can use the program it any platform or on any platform. What can run the programs written in java on any of the platforms due to the availability of the Java Virtual Machine? Java Virtual Machine will act as a platform for executing java programs. The foremost task of this machine is to convert byte code to machine code. Firstly it will load the code and verifies it in the memory. After loading the code into memory and it executes the code. JVM can be available for any platform because it is platform-independent.

1. It will specify the working of the JVM. Oracle and many other companies can provide the implementation.

2. Implementation can be done by JRE (Java Runtime Environment)

3. The runtime instance in this code is written on a command prompt to run java code.

The operations which JVM performs are:

  • Loading the class
  • Verifying the code
  • Executing the code
  • Provided the runtime environment

JVM Contains:

  • Memory
  • Class file
  • Registering the set
  • Garbage collection heap

It contains the classloader, memory area, and execution engine.

1) Classloader

This system is a subsystem of JVM for loading files. When the java program was running, it loaded in the class loader. There are three classloaders in java.

->Bootstrap ClassLoader: This is the superclass of the Extension. In this class rt.jar

    file is in java.lang package,, and java.sql packages.

->Extension ClassLoader: This is the base class of the classloader of Bootstrap and the parent class of the System classloader. The jar files are loaded inside the $JAVA_HOME/.          

JRE/lib/ext directory.

->Application classLoader: It is the base classloader for the extension class loader. The files loaded in the classpath. Classloader will set it in the classpath. The class can be changed by using the command “ -cp”. As it will switch the application, it is called an Application classloader.


//Example, for printing the class loader 
public class loader 
    public static void main(String[] args)  
        // printing the class loader for the current class    
        //classloader will load the class   
        Class c=CLoader.class;  
        //the result will be printed as null because it is a builtin class it can be founded in
        // rt.jar


Java Architecture

2) class Area

This method will store the per-class structures for storing the runtime pool and the code for storing the methods.

3) Heap

The Heap area is used for storing the objects.

4) Stack

The stack area is used for storing frames. The stack area will store the local variables and methods. Threads are created in the stack area for each new thread creation. When the method invocates, it will destroy the frame.

5) PC Register

It is a program counter register containing the address of the JVM that is currently executed.

6) Native Method Stack

can store the native methods used in the application in the Native Method stack.

7) Execution Engine

The execution engine will work as a virtual processor. It contains an Interpreter for reading the byte code, and then the instructions are executed. JIT is a Just-in-Time compiler used for performance improvement. This compiler will compile the code with similar functionality and reduce compile time. The compiler will transform instructions from JVM to CPU instructions set.

8) Java Native Interface

This interface is a framework which provides a platform to relate programs from different languages (C, C++)  to their applications. It is used to get the console output and interact with the operating system libraries.

Java Runtime Environment

It will create an environment for the execution of the program. The process works; the code is first loaded and integrated with the libraries required, and after this process starts, JVM  for running the code. Java Runtime Environment is the Java Development kit(JDK) subgroup. It contains the class libraries and stand-alone JVM. It is one most available environments for executing java programs. Using the JRE, the written code is converted to byte code for executing the byte code JRE required in any platform. JRE will be on top of most of the operating systems.

It contains:

  • Java web start can be done using JRE
  • Interfaces toolkits ex: java 2D
  • It contains the libraries for connecting the Database(JDBC).
  • Predefined libraries such as lang and util.
  • It also includes some libraries like Java Management Extensions (JMX) and java processing libraries.

What does JRE contain?

The components of JRE are:

  •  Deployment technologies the technologies are deployment, plug-in etc.
  • Interface toolkits are for designing applications interfaces, such as Abstract Window Toolkit(AWT), Swings, Applet, Sound and input methods.
  • Libraries Java Data Base Connectivity(JDBC), Java Naming And Directory Interface(JNDI), Remote Method Invocation(RMI).
  • Other libraries include I/O input and output, extension mechanisms, Net Beans, Java Native Interface(JNI), Math module, Overriding mechanism, Serialization method and XML processing in java.
  • Base libraries include the lang, util, Zip files,  Java Archive (JAR) files, Collections, API performances, and Re Expressions(Regular Expressions).
  • Java Virtual Machine will act like a server connecting the Server to the Virtual Machine and client.

Working of JRE with the JVM

Java Architecture

JRE contains Java Virtual Machine inside it, Library classes, and Development tools.

We can understand the working of JRE with the help of the below program.


import java.util.*  
public static void main(String[] args){  
System. out.println(?Hi Everyone?);  

After completing the program's writing, you can save the program with the .java extension. After saving the program with the java extension, it will be compiled using the javac The result is Bytecode, independent of the platform, so it can run in any JRE software. From this, the work of JRE begins. The following diagram describes the flow of byte code:

Java Architecture

The steps which are taken at runtime:

  • Class loader
    In this step, the class loader will load the required classes for running the code. It will load dynamically from JVM. The class loader which is used are:

1. Bootstrap class loader
2. Extensions class loader
3. System class loader

  • Byte code verifier
    It will work as security checking the Bytecode to reduce disturbance for an interpreter. Can do the interpretation of code only once.
  • Interpreter
    An interpreter will read the code line by line by following the functions:

    Execution of the byte code.
    Making calls to hardware.

In the above process, can exe can execute the program in JRE.

Java Development Kit (JDK)

The Java Development kit is an environment to develop software applications and dynamic web pages(Applet). JDK contains JRE and the development tools. Any of the below java platforms can implement JDK by Oracle corporation:

  • Standard Edition
  • Enterprise Edition
  • Micro Edition

JDK contains virtual machines and others like interpreter java, compiler javac, and archiver jar for developing java Applications. There are different kinds of components available in JDK:

Applet viewer:Without having any web browser, the running and debugging of applets can be done by this.
Apt:It is used for processing.
Next check:It is used for the detection of conflicts.
Java:The development and deployment process can be done with a single launcher. Java is used for loading the applications. It is an interpreter which generates class files.
Jmc:It is the mission controller
Jps:It is a java virtual machine process status tool used to instrument the virtual machine's hotspot.
Policy tool:It will create a policies management tool, which is used in determining runtime and other sources.
Wsimport:It is used for invoking web services.
keytool:The use of this tool is for keystores manipulation
TranscriptIt is a command line script
JavainfoThis component's utility is getting the information from the java machine.