How to compare float and double values in Java? Example Tutorial

If you have been doing Java programming then you may know that the use of == operator is not the correct way to compare floating point values in Java. If you use equality operator to compare float and double variables then it can cause an endless loop in Java, but is there a way to prevent that loop from running infinitely? Yes, instead of using == operator, you can use relational operator e.g. less than (<) or greater than (>) to compare float and double values.

Java Program to Reverse an Integer Number without using String - Example

When I was asked "Can you write a program to reverse a number in Java" long long years back, I did a trick. I converted the number to String by just concatentating with empty String e.g. "" + 123 and then converted that Stirng to StringBuilder can caled the reverse() method.

That solved the problem but Interviewer was not satisfied. He said Ok, but then asked again, can you reverse a number without using anything String or StringBuilder and by building your logic with basic programming elements. I was confused, what do you mean by basic programming elements? He said, I can use loop, if block, operator, and other basic stuff which makes a programming language.

How to Check if Given Number is Prime Number in Java

Before writing a progarm to check if a number is prime or not, let's first revise what is a prime number? In Maths, a number is said to be prime if it is not divisible by any number other than itself. You can now convert this definition to code and create your Java program to check if given number is prime or not.

How to Calculate Factorial in Java using Recursion and Loop

You can calculate factorial of a given number in Java program either by using recursion or loop. The factorial of a number is equal to number*fact(number-1), which means its a recursive algorithm and that's why it is often used to teach recursion to programmers in computer programming classes.

But, recursion is not always preffered in production code and that's why you also need to learn how to convert a recursive algorithm to an iterative algorithm i.e. algorithm which make use of various loop construct in Java programming language.

Here in this Java beginners tutorial, I'll teach you both ways to calcualte factorial in Java i.e. with and without recursion. Since recursive algorithm is very simple, we'll fisrt look at that and later we'll check out how to calculate factorial without recursion.