Example program to check whether a Number is Prime or Not in Java

In this tutorial, we will discuss the concept of an Example program to check whether a Number is Prime or Not in Java

In this post, we are going to learn how to check a number is prime or not using for, while, and do-while loop in Java programming language:

The number that can be divided by 1 and itself. it is called prime number

for Example 2,3,5,7,11,13….

Example to program for check whether a Number is Prime or Not in Java — Check prime or not

To understand this example program, you should have previous knowledge of the following Java topics

for loop in Java language

while loop in Java language

do-while loop in Java language

if statement in Java language

Example program to check whether a Number is Prime or Not

Find the prime number using the for loop

In this program, we will check whether the given number is prime or not, using for loop, first, the user is asked to enter a number randomly, then the program checks if the given number is prime or not

Program 1

import java.util.Scanner;
class Check_Prime{
public static void main(String args[]){
int num;
boolean isPrime=false;
    Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
System.out.print("Enter a number: ");
num=scan.nextInt();//get input from the user for num1

for(int i=2; i<=num/2; i++){
    
    //condition for non-prime
    if(num%i==0)
    {
        isPrime=true;
        break;
    }
}

if(!isPrime){
    System.out.println(num+" is a prime numbner ");
}
else{
    System.out.println(num+" is not a prime numbner ");
}
}
}

When the above code is executed, it produces the following results

Case 1

Enter a number: 23
23 is a prime number

Case 2

Enter a number: 54
54 is not a prime number

This program allows the user to enter a positive number and then it will check the given number is a prime number or not using for loop in Java language

Find the prime number using the while loop

In this program, we will check whether the given number is prime or not, using while loop, first, the user is asked to enter a number randomly, then the program checks if the given number is prime or not

Program 2

import java.util.Scanner;
class Check_Prime1{
public static void main(String args[]){
int num;
boolean isPrime=false;
    Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
System.out.print("Enter a number: ");
num=scan.nextInt();//get input from the user for num1

int i=2;
while( i<=num/2){
    
    //condition for non-prime
    if(num%i==0)
    {
        isPrime=true;
        break;
    }
     i++;
}

if(!isPrime){
    System.out.println(num+" is a prime numbner ");
}
else{
    System.out.println(num+" is not a prime numbner ");
}
}
}

When the above code is executed, it produces the following results

Case 1

Enter a number: 12
12 is not a prime number

Case 2

Enter a number: 37
37 is  a prime number

This program allows the user to enter a positive number and then it will check whether the given number is a prime number or not, using a while loop in the Java language

Find the prime number using the do-while loop

In this program, we will check whether the given number is prime or not, using do-while loop, first, the user is asked to enter a number randomly, then the program checks if the given number is prime or not

Program 3

import java.util.Scanner;
class Check_Prime2{
public static void main(String args[]){
int num;
boolean isPrime=false;
    Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
System.out.print("Enter a number: ");
num=scan.nextInt();//get input from the user for num1

int i=2;
do{
    
    //condition for non-prime
    if(num%i==0)
    {
        isPrime=true;
        break;
    }
     i++;
}while( i<=num/2);

if(!isPrime){
    System.out.println(num+" is a prime numbner ");
}
else{
    System.out.println(num+" is not a prime numbner ");
}
}
}

When the above code is executed, it produces the following results

Case 1

Enter a number: 100
100 is  not a prime number

Case 2

Enter a number: 101
101 is not a prime number

This program allows the user to enter a positive number and then it will check whether the given number is a prime number or not using the do-while loop in the Java language

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