Prime numbers are excellent tools used in computers for cryptography and encryption purposes. They’re also a big part of programming tests because writing a program for prime numbers in Java helps you learn the basics of coding, and teaches you a lot about if-then statements, break statements, and loops in the process.

If you’re new to programming, you’ll want to learn how to write a program that can check for prime numbers so that you can improve your skills.

This article will cover the basics of making a program for prime numbers in Java. 

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What Is Java?

Java is a universal programming language and platform in one. It’s a high-level, object-oriented language developed by Sun Microsystems in 1995 and was created so that applications written in Java could run just about anywhere. Java is called a platform because it comes with a run-time environment, the Java Run-time Environment, and an API.

What Are Prime Numbers?

Before you write a program for a prime number in Java, you’ll need to understand what a prime number is.

A prime number is any number that’s greater than one, and that is divisible by one. 

2, 3, 5, 7, and 11 are some examples. The only even prime number is 2 because every single other prime number can be divided by 2. Zero and one are not prime numbers. 

Prime numbers are commonly used in computing because of encryption because cryptography is about general number theory. Specific encryption algorithms make use of the fact that prime factorization takes a whole lot of time. 

The product of two prime numbers can be used as a public key, while the primes themselves can be used as a private key. It will take years or centuries to factor the kinds of prime numbers that we employ in cryptography, even on the fastest computers. This is what makes encryption so safe and why learning to write a program for prime numbers in Java can be so valuable. 

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How Do I Write A Program To Identify Prime Numbers?

A Java program to find prime numbers is something you’ll see in many beginner Java tutorials. You need first to check if the number is a natural number. Then you need to use the IsPrime method to check if the number is a prime number or not. Make sure to specify the start and end number while checking for a prime number in Java. Then use a loop to print the prime number. This is how you know your program for prime numbers in Java is complete. Most people that struggle with the code need to brush up on loops, break statements, and if-then functions, so let’s explore those a little more.

What Are Loops In Java?

A loop is a feature in Java that allows the execution of a set of instructions repeatedly while the condition remains true. If you want to learn how to check prime numbers in Java, loops are essential to understand.

There are three main ways to execute a loop in Java. While many ways provide the same basic performance and functionality, they vary slightly in syntax and checking time. What are the different types of loops?

1. The while loop:

This loop is a simple flow statement that lets code execute again and again based on a set Boolean condition. You can think of the while loop as a repeating if statement if that makes things simpler.

2. The for loop:

This loop gives you a simple way to write the entire loop structure. Unlike a while loop, a for statement focuses on the initialization, condition, and increments in a single line. This is a quick, easy way to debug the structure of the looping.

3. The do-while loop:

This loop is like the while loop but different in its own way. It checks for the condition only after executing the statements. This makes it a good example of an exit control loop.

What Are If-Then Statements In Java?

Java has all the usual support of logical conditions from math. It understands less than symbols, less than or equal to, greater than, greater than or equal to, equal to, and not equal to statements. This allows you a lot of power in the kind of code you write.

You can use any of these functions to perform different actions in Java. And Java also comes with some additional conditional statements.

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What Is A Break Statement In Java?

Break statements are a kind of loop control. These are used to stop a loop. When your program sees the break statement in a loop, it stops the iterations right there. Control then returns from the loop to the first statement after the loop.

These commands are used in situations where you’re unsure about the actual number of repeats for the loop you need. Or if you want to stop the loop based on a condition instead.

You use this function to terminate a sequence, exit a loop, or use it as a form of goto. For example, break statements are essential when writing a Java program to check prime numbers.

How Do I Make A Java Program To Check Prime Number Using Recursion?

Program For Prime Number In Java

Now can you write a program for prime numbers in Java that makes use of recursion?

Let’s look at a sample program:

package prime;

import java.util.Scanner;

import java.util.Scanner;

public class Recursion {

public static void main(String[] args) {

Scanner s = new Scanner(;

System.out.print(“Enter a number : “);

int n = s.nextInt();

if (isPrime(n)) {

System.out.println(n + ” is a mathematical prime”);

} else {

System.out.println(n + ” is not a mathematical prime”);



public boolean static isPrime(int n) {

if (n<= 1) {

return false;


for (int i = 2; i< n; i++) {

if (n % i == 0) {

return false;



return true;



The Scanner class is a class that’s inherently present in the util package. This allows the user to understand and read the values of various types.

Check if the number you’re dealing with is a natural number or not using the if condition. If the number isn’t prime, then print that the number is not a prime number.

Check for the condition of the division next. See if the remained is zero or something else. If you have a zero, then it’s not a prime number. 

If you’ve understood all of the above, then you’ll be able to write a program for prime numbers in Java with ease.

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What About BigInteger?

This class is used for integers that are greater than 64 bits. It can also help you write a program for prime numbers in Java.

One of the APIs you’ll want to look out for is isProbablePrime. This gives a positive if there’s a probability of the number being prime. This gives a false in case the number is a composite. It’s that simple. This one is useful when handling large integers as it’s a serious commitment to verify these in-depth.

The Miller-Rabin is a test to iterate a specific number of times for finding primality. This iteration count uses simple checks that involve the value passed down towards the API and bit length of the number. And that’s how you use BigInteger to find a prime number in Java.

What About Apache Commons Math?

This method isn’t mandatory for writing a program for prime numbers in Java, but it certainly helps and checks the primality of a number. 

First, import the Apache commons math library by adding a dependency clause to your pom.xml. All you have to do is use the method Primes.isPrime(number); to complete the check. That’s how to find a prime number in Java with Apache commons in a nutshell.

Why Java Is A Great First Programming Language?

Java is one of the best first programming languages you can learn. While it’s not the newest language out there, it has a lot of things going for it, which explains why it’s been prominent in the software field for more than 20 years. 

One of the biggest advantages of picking up Java is that there’s an incredible amount of learning materials out there because of how long it has been around. There are plenty of communities, books, videos, and multiple generations of programmers who started in Java and are veterans now. You won’t have any difficulties finding a teacher to teach you how to find a prime number in Java because there are many Java experts out there.

There will always be new programming languages that pop up year after year, but what you learn in Java easily carries over into other languages. Most of the concepts of using an object-oriented language transfer to other languages with ease. It was developed with its skeleton syntax from C, so learning C++ and C# is much easier once you know Java.

If you don’t intend to follow a traditional software engineer path, learning Java can help you enter the mobile app development market. There are plenty of startups and businesses looking for app developers to help them disrupt and revolutionize the market. Finding a prime number in Java might be your first step to becoming an app developer.

What Should I Aim For As A Beginner Programmer?

Programming for prime numbers in Java is your first step toward learning to think like a programmer. Java isn’t just a good language; it’s a good vehicle for learning other languages as well. A strong foundation in Java typically translates into better overall programming skills. 

Plenty of students who graduate from Java courses pursue jobs in other languages such as C#, Ruby, Python, and JavaScript.

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If Java is your first programming language, it’s probably going to be the most complex language you’ll learn. But once you’ve got Java down, you can start learning other languages with ease because so many of the same skills you learn in Java will transfer over to other languages. By the time you finish learning how to write a program for prime numbers in Java, you’ll have better fundamentals that will serve you well in your career as a programmer.

Java is a powerful and versatile language. It’s a great option for beginner programmers to check out. It opens you up to the mobile app development market and may help you secure a job in any big tech companies because it’s always in demand, even if it’s not the most cutting-edge and latest language out there.

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