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Showing posts from 2021

Singleton class in java

What is Singleton class Singleton is a design technique which gaurantees that there will be only instance of a class globally. Such classes are required when we need to create some objects which are memory/ resource extensive and we can't afford many such objects. Using singleton We can maintain single object per JVM per classloader. Classloader could be different in different hierarchy and in such case we may have more than one instances of singleton but we can avoid it by loading it at appropriate classloader. For example in an ear application there could be multiple web modules and each one of them will have their own singleton instance. Sometimes it may be a need but sometimes it could be a flaw which can be resolved by loading it either at ear level or web module level as per requirement. Implementing singleton class There are two different ways to implement singleton in java. Using singleton design pattern In this pattern we can create singleton either using lazy

Print English alphabets using for loop in Java

 In this post we will see how we can print the english alphabets [a-z] using for loop. One way is to have a character array of a-z and print it using loop. But there is another way to just print them using ascii code. What is ascii code There are total 256 numbers in ascii and each of which represents a specific character including alphabets. Numbers from 65-90 represents the alphabets in capital case [A-Z] and numbers from 97-122 represents alphabets in small case [a-z]. Printing alphabets using for loop with ascii numbers Below code prints alphabets in both capital and small cases using for loop. Here you can see we are using ascii numbers in for loop which are printed after type casted to character type where it automatically translate the number to equivalent character. public class PrintAlphabetsUsingLoop { public static void main(String[] args) { int alphabetsCount = 26; int capitalLetterStart = 65; int smallLetterStart = 97; System.out.println("Printing lette