prime number program in java codeYourslf
In this section you can learn how to write a prime number program in java with 3 different approaches.
Approach:-1 "java program to check prime number using for loop"
public class UsingforLoop {
public static void main(String[] args){
int num = 13,count = 0;
if(num == 0 || num == 1){
System.out.println("It is not prime number");
}
else{
for(int i = 2; i < num/2; i++){
if(num % i == 0){
count += 1;
break;
}
}
if(count == 0){
System.out.println("It is a prime number");
}
else{
System.out.println("It is not prime number");
}
}
}
}
A number is said to be prime if it only divisible by 1 and itself.
Ex :- 7, if we tried to divide 7 with other numbers it must give some reminder it means 7 is not completely divisible by other numbers except 1 and itself i.e 7.
In programming we can check prime of a number by using that modulus operator, which returns the reminder of any number.
Here inside for loop we have started dividing the number from 2 upto the previous of that number. And in if else part we are checking for divisibility by these numbers using modulus operator.
If number satisfied num % i == 0, then the number is not prime. Because it is divisible by more than two numbers.
Output
Approach:-2 "prime number program in java using method"
public class usingMethod {
public static void main(String[] args){
isPrime(2);
isPrime(15);
isPrime(19);
}
public static void isPrime(int num){
if(num == 0 || num == 1){
System.out.println("This is not prime number");
}
else{
int count = 0;
for(int i = 2; i < num/2; i++){
if(num % i == 0){
System.out.println("It is not a prime number");
count += 1;
break;
}
}
if(count == 0){
System.out.println("The number is prime");
}
}
}
}
In this program I have used method concept to check whether a number is primer or not.
Here I have declared a static method and inside that I have used while loop to check the logic. Here logic remain same for this problem also.
Approach:-3 "check prime number in java with user input by scanner class"
import java.util.Scanner;
public class primeNumberScanner {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number: ");
int num = sc.nextInt();
checkPrimeNumber cp = new checkPrimeNumber();
boolean result = cp.isPrimeNum(num);
if (result) {
System.out.println("This is prime number");
} else {
System.out.println("This is not prime numer");
}
}
}
class checkPrimeNumber {
public boolean isPrimeNum(int num) {
if (num == 0 || num == 1) {
return false;
} else {
for (int i = 2; i < num / 2; i++) {
if (num % i == 0) {
return false;
}
}
return true;
}
}
}
In this program I have used another concept of method and here I also use the user input concept for prime number program in java.
Here I have used a separate class i.e checkPrime, inside that I have declared a Boolean method named isPrimeNumber().
If the condition satisfy I have returned true otherwise false. And in the main method I have received that return value in a result variable.
And using ternary operator I have checked result is true or false. If result become true I have printed this is a prime number, in the other hand number is not prime.
Here ternary operator works like if else statement.