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 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


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

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


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

Stack vs Heap in Java

In Java, whenever we declare an object or create a variable, whether it is an instance variable, local variable, or static variable, a certain memory is used to store the data. The amount of data or size is determined by the type of data type declared. In Java, there are two types of data, primitive and non-primitive.

Primitive data types:

TypeSize (in bits)

Non-primitive data type:

  1. Class
  2. Object
  3. String
  4. Array
  5. Interface

There are significant distinctions between primitive and non-primitive data types, which are as follows.

  1. The primitive data types are initialized and declared while keeping the first letter in the small case. In contrast, the non-primitive datatypes are initialized and declared while keeping the first letter in a large case. Because non-primitive data types are treated as objects in Java. For example:
String st = "Sahil"; // non- primitive data type
int a = 100;        //primitive  data type 
  • Variables in primitive data types can only store one value at a time, whereas non-primitive data types allow us to store numerous values of the same or distinct types.
  • For primitive type variables, the stack retains all of the data, whereas, for reference types, the stack holds a pointer to the object on the heap.

Java's memory management plays an important role in its functionality. Java Virtual Machine properly uses both the memory to execute the program. And thus, to do so, the memory in Java is divided into the following types: stack memory and heap memory.

Stack Memory

Stack memory is also known as Java's temporary memory, storing variables and order of method execution. It uses a linear data structure. The stack implements the concept of LIFO order. To understand how the stack works, imagine a pile of books. The only way to take out a book lying in the middle of the pile of books is by taking out books above it one by one.

Similarly, stack stores data in a pile or a stack. To access the data at the bottom, you need to remove all the above data. It implements the following interfaces.

  • List
  • Iterable
  • Collection
  • Cloneable
  • RandomAccess
  • Serializable

It performs the following operations:

empty ()

This is a return type method; return true if the stack is empty.

peek ()

This is a return type function that returns the stack's top element. When the stack is empty, this function throws an EmptyStackException.

pop ()

This return type function returns the top element from the stack. This method invokes EmptyStackException when the stack is empty.

push ()

Adds a new element to the stack's top.

Heap Memory

It is used when we need is to store object classes and dynamically allocate memory. The memory is created when the Java Virtual Machine initiates its function, and the allocation of size may increase or decrease. Whenever a new object is created or declared, space is given to it in heap memory, while the reference variable of the same object is stored inside the Stack Memory. Unlike the stack, the heap memory does not store the data in any order, i.e., it does not store memory continuously. It has a feature called Garbage Collector. It deletes all the objects which are no longer being used. When the heap memory has no space to store a new object, it invokes Java.lang.OutOfMemoryError.

String arr = new String ();
arr = "Sahil Deshmukh";

The reference variable arr is stored in stack memory in the above code, and its value Sahil Deshmukh is stored in heap memory. The heap memory is further segregated into the following parts: -

  • Permanent generation
  • Code Cache
  • Young generation
  • Old generation
  • Survivor Space

Difference Between Stack and Heap

Stack MemoryHeap Memory
It acts as Random-access memory for Java and stores variables, methods, and reference variables.It stores objects.
It implements the LIFO order.It does not implement any order and dynamically allocates memory.
Users are not permitted to alter changes or manipulate the memory.Users are allowed to alter the memory.
It is comparatively faster in allocating memory.It is comparatively faster in allocating memory.
It is comparatively smaller in size.It is comparatively larger.
It continuously allocates memory.It randomly allocates memory.
It is thread-safe since each thread has its stack.Correct code synchronization is essential as it is not a thread-safe.
When the stack’s size reaches its limits, It throws Java.lang.StackOverFlowError. When the heap memory has no space to store a new object, it invokes Java.lang.OutOfMemoryError.
The stack memory exists only as long as the current method is active.Once the current application is closed, the heap space also gets closed.