java program to print prime numbers in a given range

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}

1Now let’s see print first 10 prime numbers in java.
2
3public class FirstTenPrimeNumbers
4{
5   public static void main(String[] args) 
6   {
7      int count = 0, number = 0, a = 1, b = 1;  
8      while(number < 10)  
9      {  
10         b = 1;  
11         count = 0;  
12         while(b <= a)  
13         {  
14            if(a%b == 0)  
15                count++;  
16            b++;
17         }  
18         if(count == 2)  
19         {  
20            System.out.printf("%d ", a);  
21            number++;  
22         }  
23         a++;  
24      }
25   }
26}

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}

1It will display the prime numbers between 1 and 100.
2
3class PrimeNumbers
4{
5   public static void main (String[] args)
6   {		
7       int i =0;
8       int num =0;
9       //Empty String
10       String  primeNumbers = "";
11
12       for (i = 1; i <= 100; i++)         
13       { 		  	  
14          int counter=0; 	  
15          for(num =i; num>=1; num--)
16	  {
17             if(i%num==0)
18	     {
19 		counter = counter + 1;
20	     }
21	  }
22	  if (counter ==2)
23	  {
24	     //Appended the Prime number to the String
25	     primeNumbers = primeNumbers + i + " ";
26	  }	
27       }	
28       System.out.println("Prime numbers from 1 to 100 are :");
29       System.out.println(primeNumbers);
30   }
31}