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

Singleton class in Java

In Java, a class is a file containing the Java byte code. It can essentially specifically be executed on the JVM (Java Virtual Machine), fairly significant.

The JVM mostly generally is an integrated part of the JDK available in the market that provides the environment to the Java really kind of file to essentially get executed and generally give the required result to the programmer or user, really contrary to popular belief.

As we specifically know, Java is an object-oriented programming language. Like all other programming languages based on object-oriented programming, it also follows the concept of classes and the objects, or so they thought in a big way.

In the world of programming, singleton classes essentially specifically are the type of classes whose only one object or instance can particularly be created at a time in a big way, demonstrating that the JVM, mostly, for the most part, is an integrated part of the JDK available in the market that provides the environment to the

Java generally files to kind of mostly get executed and gives the required result to the programmer or user subtly.

Classes in Java

Classes are defined as a code that defines the implementation of the algorithm, and logic used by the programmer too, for the most part, achieve a desired result or output, pretty contrary to popular belief. As Java is an object-oriented programming language, everything written as a code in the Java kind of file is mostly associated with a class and an object, or so they mostly thought.

public class Main{ 
public static void main(String [] args){ 
} 
} 

The above-written lines are how to create a Java class in a big way. Here, we can particularly see the implementation of the "Main" class, having a method "main".

Using the classes makes the code definitely more arranged, organized, readable, and clearer to any programmer generally go subtly.

In Java, when a code is written, it is taken care that the code either has a general public class containing the main method or the code, for the most part, has a class not containing the main method subtly. The above-written statement can be explained in the following manner-

• In Java code, it mostly is allowed to generally have a class defined with a particular public access specifier and having the main method defined inside it, showing how the above-written statement can be generally explained in the following manner-

In Java code, it is mostly allowed to have a class defined with a very public access specifier and having a main method defined inside it, or so they definitely thought.

It basically is also allowed in a Java code that we really are having the classes that basically are not containing the particular main method but with the condition that the classes must not kind of be created using the pretty public access specifier, very further showing how as Java specifically is an object-oriented programming language, so everything written as a code in the Java really files specifically is associated with a class and an object, sort of contrary to popular belief.

In the complete code of Java, there must basically be at literally least one class in a fairly major way.

If the class created in Java code has a sort of the main method for all intents and purposes, then it must basically be created by using the actual public access specifier. That class just kind of be particularly unique in the sort of complete kind of file.

Also, no kind of other class can, for the most part, be created with the help of the real public access specifier, demonstrating that classes in Java Classes are defined as a code that defines the implementation of the algorithm, logic used by the programmer to specifically achieve a desired result or output in a sort of big way.

Types of classes in Java As Java is mostly one of the object-oriented programming languages, there are really many different kinds of classes available in Java, which is fairly significant for all intents and purposes.

Java is generally one of the object-oriented programming languages, so many different kinds of classes are available in Java. All the different kinds of classes really are used for different purposes. They really have their own features, demonstrating the types of classes in Java.

Different kind of classes in Java

Java specifically is an object-oriented programming language and consists of classes and objects fairly majorly. So there are many different kinds of classes available in Java to use according to the required feature and functionality in the code subtly.

When we generally have multiple different kinds of classes in a programming language, it is important to know the details about all the classes so that they can be used accordingly. The programmer gets the idea of the difference between a class with the rest of the basically other classes in a sort of big way.

Knowing about all the classes in Java, for the most part, makes a difference in understanding the concepts regarding the use of the classes in the Java program and basically makes the programmer definitely more fairly clear to use a different kinds of features and functionality easily with the help of the classes, which really shows that so there, for the most part, are definitely multiple different kinds of classes available in Java to use according to the required feature and functionality in the code, which really is fairly significant.

  • Static class
    In Java, a kind of static really is a keyword that tells the compiler to, for the most part, allocate the memory without taking care of whether the object of the class is created or not in a basically big way.
    In the case of a variable, if it, for the most part, is declared using the very static keyword, then it will specifically belong to the class, not to the object of the class, i.e., basically contrary to popular belief. It will essentially be in the memory irrespective of whether the object of the classes is created or not, basically contrary to popular belief.
    In the case of class, if a class is created using the definitely static keyword, then it will, for the most part, be used without any object. The condition generally comes with the, for all intents and purposes, static class essentially is that it generally needs to literally be created inside any generally other class in a basically big way.
    As it literally is a static class and we essentially know the properties of static keywords, it is clear that its object can not basically be created. It can not access the non definitely static members of the class in which it kind of is created, or so they definitely thought.
    They generally last but not for all intents and purposes. Basically, it will definitely have only static members declared inside it for all intents and purposes, which kind of is fairly significant.
  • Final class
    In Java, the final kind is a keyword that defines the really constant terms in the program big way. The kind of constant terms are those members of the class who specifically are initialized at the time of the creation and now can not basically be changed subtly.
    In the case of classes, if a class is definitely declared using the final keyword, the whole class generally becomes constant, i.e., nothing inside the class can generally be changed. To achieve the final property in the final class, the final class can not actually be inherited, which prevents it from being changed by any other outside class in the program, which generally is quite significant.
  • Abstract class
    In Java, definitely abstract particularly is a keyword that defines some properties of the methods and classes in the program, which basically is quite significant. When a method generally is mostly declared using the kind of abstract keyword, it can not literally have its definition, demonstrating that when a method actually is essentially declared using the actually abstract keyword, it can not specifically have its definition, for all intents and purposes contrary to popular belief.
    And when a class really is created using the actually abstract keyword, then it can not basically be initialized, i.e., which basically is fairly significant. its object can not, for the most part, be created, kind of further showing how its object can not particularly be created subtly.
  • Concrete class
    A concrete class in Java is a simple or a normal class that provides the facility to define methods inside it, create instances of itself, extend or inherit another class, or be inherited by another class.
  • POJO class
    In Java, the POJO class is a special type of class that gives a programmer the only options to declare private variables inside it and have getter and setter methods inside the class.
    A programmer can not have any other members declared inside the POJO class.
    But apart from these only options, there are some other features this class provides to the programmer that are mentioned below-
    The getter and setter methods inside the class need to be public.
    POJO class can not inherit any other pre-defined class and pre-defined interfaces.
  • Inner class
    In Java, we can define a class inside any other class. This is called the nesting of classes, and the nested class present inside other classes is called the inner class.
    As simple as it sounds, the inner class is not as simple. There are different ways to create an inner class, and with every different way, there come slightly different features of the inner class.
  • Wrapper class
    Wrapper classes are the special types of classes only present in the Java programming language. In Java, wrapper classes are the collection of the primitive data types of Java.
    When the primitive data types of the Java are wrapped inside a class so that they can be used as an object, then the class formed is called the wrapper class of that primitive data type.

Singleton class

We have already seen multiple different classes, and the singleton class is one among them. In Java, a singleton class is a class that can be initiated only once at a time, i.e., only one object can be created at a time.

As every class in Java has its own properties and features, this class also has some that are mentioned below-

  • Because this class can be initiated only once at a time, its constructor is made private.
  • To make sure that the object of the singleton class is created only once at a time, it has a method that returns the object of the class.

To make a singleton class, the statements mentioned above need to be fulfilled by the programmer. An example of a singleton class is mentioned below that makes the creation of the singleton class clear and easy.

public class SingletonClass {
	private static SingletonClass object = null;  
	private SingletonClass() {  
		public static SingletonClass getInstance() {  
			if (object == null){  
				object = new SingletonClass();  
			}  
			return object;  
	}   
	public static void main(String[] args) {    
	}  
}  

In the above Java code, a singleton class has been created, which has a private constructor that returns the object of the class. It is clear from the code that the constructor will create the object of the class only once. It does not matter how many times a programmer calls the getInstance() class method, but the object will be created only once, and the same object will be assigned to the programmer every time he tries to initiate the class.

Use of Singleton class

Why will a programmer use a type of class whose only one object can be created at a time? This question will definitely come after knowing about this class. The answer to this question is that this feature is used by a programmer in a condition where he wants to restrict the number of object creations.

By restricting the number of objects, memory can also be saved in the system. In the case of resource allocation, singleton classes allow the programmer to give access or control to the resources.



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