Java program for display first n prime numbers

Java program to display first n prime numbers

In this article, we will discuss the concept of Java program for display first n prime numbers

In this code, we are going to learn how to display first n prime numbers  using different methods in Java language.

This is done using for loop,while loop, do-while loop and method in Java language

Code to display first n prime numbers

Code to display first n prime numbers using for loop

In this program, we will display first n  prime numbers using for loop in Java language

Program 1

import java.util.*;
public class PrimePrint_firstNfor{
public static void main(String args[]){
  Scanner sc=new Scanner(System.in);
  //scanner class for input
int n,num=1,y=3,count,j;
System.out.println("Please Enter the number of prime you want: ");
n=sc.nextInt();
if(n>=1){
  System.out.println("First "+n+" prime numbers are: " );
  System.out.println(2);
}
for(count=2; count<=n;){
  for(j=2; j<=Math.sqrt(y); j++){
    if(y%j==0){
      num=0;
      break;
    }
  }
  if(num!=0){
    System.out.println(y);
    count++;
  }
  num=1;
  y++;
}
}
}

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

Please Enter the number of prime you want:
18
First 18 prime numbers are
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61

 

Code to display first n prime numbers using while loop

In this program, we will display first n  prime numbers using While loop in Java language

Program 2

import java.util.*;
public class PrimePrint_firstNwhile{
public static void main(String args[]){
  Scanner sc=new Scanner(System.in);
  //scanner class for input
int n,num=1,y=3,count,j;
System.out.println("Please Enter the number of prime you want: ");
n=sc.nextInt();
if(n>=1){
  System.out.println("First "+n+" prime numbers are: " );
  System.out.println(2);
}
count=2;
while(count<=n){
  j=2; 
  while(j<=Math.sqrt(y)){
    if(y%j==0){
      num=0;
      break;
    }
     j++;
  }
  if(num!=0){
    System.out.println(y);
    count++;
  }
  num=1;
  y++;
}
}
}

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

Please Enter the number of prime you want:
12
First 12 prime numbers are
2
3
5
7
11
13
17
19
23
29
31
37

 

Code to display first n prime numbers using do-while loop

In this program, we will display first n  prime numbers using do-while loop in Java language

Program 3

import java.util.*;
public class PrimePrint_firstNDowhile1{
public static void main(String args[]){
  Scanner sc=new Scanner(System.in);
  //scanner class for input
int n,num=1,y=3,count,j;
System.out.println("Please Enter the number of prime you want: ");
n=sc.nextInt();
if(n>=1){
  System.out.println("First "+n+" prime numbers are: " );
  System.out.println(2);
}
count=2;
do{
  j=2; 
  do{
    if(y%j==0){
      num=0;
      break;
    }
     j++;
  }while(j<=Math.sqrt(y));
  if(num!=0){
    System.out.println(y);
    count++;
  }
  num=1;
  y++;
}while(count<=n);
}
}

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

Please Enter the number of prime you want:
15
First 15 prime numbers are
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47

 

 

Code to display first n prime numbers using method

In this program, we will display first n  prime numbers using method in Java language

Program 4

import java.util.*;
public class PrimePrint_firstNMethod{
static void printPrimenum(int N){
int num=2,primeCount=0;
while(primeCount<N){
if(isPrime(num)){
  System.out.println(num+" ");
  primeCount++;
}
num++;
}
}

static boolean isPrime(int n){
  
  for(int j=2; j<=Math.sqrt(n); j++){
    if(n%j==0)
      return false;
}
return true;
}
public static void main(String args[]){
  Scanner sc=new Scanner(System.in);
  //scanner class for input
System.out.println("Please Enter the number of prime you want: ");
int N=sc.nextInt();
System.out.println("First "+N+" prime numbers are:");
printPrimenum(N);
System.out.println();
  
}
}

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

Please Enter the number of prime you want:
20
First 20 prime numbers are
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71

 

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