java program to print prime numbers upto n

1// Java program to print prime numbers in a given range
2public class PrimeNumberRangeDemo 
3{
4   public static void main(String[] args) 
5   {
6      int lowerRange = 10, higherRange = 50;  
7      while(lowerRange < higherRange) 
8      {
9         boolean flag = false;
10         for(int a = 2; a <= lowerRange / 2; ++a) 
11         {
12            if(lowerRange % a == 0)
13            {
14               flag = true;
15               break;
16            }
17         }
18         if(!flag && lowerRange != 0 && lowerRange != 1)
19             System.out.print(lowerRange + " ");
20         ++lowerRange;
21      }
22   }
23}

1// Java program to print prime numbers from 2 to n
2import java.util.Scanner;
3public class PrimeNumberFrom2Ton
4{
5   public static void main(String[] args) 
6   {
7      int loop, max;
8      System.out.print("Please enter highest (maximum) number: ");
9      Scanner sc = new Scanner(System.in);
10      max = sc.nextInt();
11      for(loop = 2; loop < max; ++loop)
12      {
13         if(findPrime(loop))
14         {
15            System.out.println(loop);
16         }
17      }
18      sc.close();
19   }
20   public static boolean findPrime(int number)
21   {
22      int a;
23      boolean boolPrime = true;
24      for(a = 2; a < number / 2; a++)
25      {
26         if(number%a == 0)
27         {
28            boolPrime = false;
29            break;
30         }
31      }
32      return boolPrime;
33   }
34}

1// Java program to print prime numbers upto n
2import java.util.Scanner;
3public class PrimeNumberUptoN
4{
5   public static void main(String[] args)
6   {
7      Scanner sc = new Scanner(System.in);
8      int a = 0;
9      int n = 0;
10      String strPrime = "";
11      System.out.println("Please enter the value of n: ");
12      int number = sc.nextInt();
13      for(a = 1; a <= number; a++)
14      {
15         int counter = 0;
16         for(n = a; n >= 1; n--)
17         {
18            if(a % n == 0)
19            {
20               counter = counter + 1;
21            }
22         }
23         if(counter == 2)
24         {
25            strPrime = strPrime + a + " ";
26         }
27      }
28      System.out.println("prime numbers upto n are: ");
29      System.out.println(strPrime);
30      sc.close();
31   }
32}

1class PrimeNumbers
2{
3   public static void main (String[] args)
4   {		
5       int i =0;
6       int num =0;
7       //Empty String
8       String  primeNumbers = "";
9
10       for (i = 1; i <= 100; i++)         
11       { 		  	  
12          int counter=0; 	  
13          for(num =i; num>=1; num--)
14	  {
15             if(i%num==0)
16	     {
17 		counter = counter + 1;
18	     }
19	  }
20	  if (counter ==2)
21	  {
22	     //Appended the Prime number to the String
23	     primeNumbers = primeNumbers + i + " ";
24	  }	
25       }	
26       System.out.println("Prime numbers from 1 to 100 are :");
27       System.out.println(primeNumbers);
28   }
29}

1public class PrimeNumbersFrom1To100
2{
3   public static void main(String[] args)
4   {
5      int maxNumber = 100;
6      boolean prime = true;
7      String primeNumbers = "";
8      for(int a = 1; a <= maxNumber; a++)
9      {
10         prime = checkPrime(a);
11         if(prime)
12         {
13            primeNumbers = primeNumbers + a + " ";
14         }
15      }
16      System.out.println("Display prime numbers from 1 to " + maxNumber + ": ");
17      System.out.println(primeNumbers);
18   }
19   public static boolean checkPrime(int number)
20   {
21      int remainder;
22      for(int a = 2; a <= number / 2; a++)
23      {
24         remainder = number % a;
25         // if remainder is equal to 0 then number is not prime
26         if(remainder == 0)
27         {
28            return false;
29         }
30      }
31      return true;
32   }
33}