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

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 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

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 BufferedWriter Java InputStreamReader Java File Java Read File Line By Line Java FileOutputStream Jar File in Java

Serialization

Java Serialization Java transient

Networking

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

AWT

Java AWT

Swing

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

Java JDBC Tutorial

Java Differences

Java vs JavaScript Python vs Java Kotlin vs Java Java vs C++ C# vs Java Static vs Non-static in Java C vs Java int vs Integer in Java Stack vs Heap in Java Java Array vs ArrayList

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 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 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 achieve abstraction in Java How to call static method in Java

Java 8 Features

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

Java 9 Features

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

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.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

Misc

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

Memory Areas in Java

Let’s have a look at how memory management in Java works. We will be going to discuss how the objects get destroyed, working of a garbage collector, things that are managed by JVM (Java Virtual Machine).

It is necessary for a programmer to understand the working of memory management to create a high performance-based program that will not crash or if got crashed, they will aware of how to debug and overcome from the crash.

In every coding language, memory management plays a vital role in the allocation and deallocation of memory areas because it needs critical care. In Java, the JVM and the Garbage Collector manages the memory allocation.

Structure of Java Memory Areas

The JVM defines various runtime data areas that are used when we run our code. Some of the data areas are created when JVM started and destroyed in the presence of JVM, and data areas created during the initialization of the thread get destroyed when the thread exists.

Heap:

  • Heap represents the runtime data area that stores the actual object in the memory. It is created during the virtual machine start-up.
  • The memory is allocated to every class instance. The size of the heap depends upon the system’s configuration.
  • When a new keyword is used, the object is assigned a memory area in a heap, but the reference of the object exists onto the stack.

Method Areas

  • Method area store class structures, method data, and constructor field data, including the special methods used in class.
  • It is created when the JVM starts.
  • Mehtod area is logically a part of the heap area, but it may or may not be garbage collected.
  • The size of the method may be fixed or expanded as required by the computation and contracted if the method area is in use unnecessarily.

JVM Stacks

  • Each and every thread is having its own stack created at the same time as that of the thread.
  • Every stack classified into different parts called frames. These frames are used to store data and partial results and to perform dynamic linking, return value for methods, and dispatch exception.
  • Each and every stack’s frame divided into three different parts.
    • Local variable storage area
    • Operand stack
    • Frame data.
  • All the local variables going to store in the Local variable storage area, any operations on the top of the variable are going to be processed are stored in the Operand stack , and if any exception occurs during method execution, then those exceptions are going to be stored the frame data.
  • Stacks may be of fixed size or dynamic. It can be chosen independently during the stack creation.

Native Method Stacks

Native Method Stacks are the stack written in a different language other than the Java Programming language. These memory areas are allocated typically to each thread when threads are created. Size of this this memory area can be fixed or dynamic.

Program Counter (PC) registers

  • It stores the address of the Java virtual machine instruction, which is currently executing.
  • In Java, every thread has its own pc register.
  • As a Java application contains some native libraries. If the method in the application is not native (i.e., written in Java) then the program counter contains the address of the JVM instruction currently being executed, and if it is native, then the PC register’s value is undefined.

Working of Garbage Collector

JVM uses this process to automatically allocate and deallocate the memory. Garbage Collector works in below three steps.

Marking-identifies what are the object not in use

Normal Deletion- Theidentified objects that are not in use has been removed from the heap.

Deletion and Compacting- Once the unused object is removed from the heap, the memory is being allocated automatically, these memory allocations are grouped together so that in future the memory allocation will be faster.

Compacting helps us grouping the memory together, so the allocation of new memory will be increased.

Types of Garbage Collector

Serial Garbage Collector- It works by holding all the application threads. It works with single threaded environments. It has a major drawback of freezing all the application threads during garbage collection. That is why it is not suitable for the server environment. We may use it only for simple command-line programs.

Parallel Garbage Collector-It is also called as the throughput collector. It is JVM’s default garbage collector. It uses multiple threads for garbage collection, but it also freezes all the application threads while performing garbage collection.

CMS Garbage Collector-CMS stands for Concurrent Mark Sweep. It uses multiple threads to scan the heap memory for the unused objects and then removes the marked instance. It holds the application threads while marking the referenced object in the tenured generation space and if there is any chance in heap memory in parallel while doing the garbage collection.

As compared to the parallel garbage collector, it uses more CPU to ensure better application throughput.

G1 Garbage Collector: It is used when there is a large heap memory area. G1 separates the heap memory into regions and group the unused memory area in parallel. It also compacts the free heap space on the go just after reclaiming the memory.

System.gc() and Runtime.gc() are the methods that request for garbage collection to the Java Virtual Machine explicitly.



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