Find Prime Numbers Using Java

 import java.util.*;  
 public class Primes{  
      public static void main(String args[]){  
           int integer;  
           Scanner scanner = new Scanner(System.in);  
           List<Integer> factors = new ArrayList<Integer>();  
           try{  
                System.out.print("\n\n\nEnter Integer : ");  
                integer = scanner.nextInt();  
                if(integer==0){  
                     System.out.println("Error:Can not find primes for 0");  
                     System.exit(-1);  
                }  
                 for (Integer integer1 : Primes(integer)) {  
                     System.out.print(integer1+"\t");  
                }  
           }catch(Exception e){  
                System.out.println("Error:Integer values must be given");  
           }  
      }  
      private static List<Integer> Primes(int integer){  
           List<Integer> factors = new ArrayList<Integer>();  
           for (int i = 1; i <= integer; i++) {  
                for(int j=2;j<=i;j++){  
                     if(i==j){  
                          factors.add(i);  
                          break;  
                     }  
                     //value is not prime  
                     if(i %j==0){  
                          break;  
                     }  
                }  
           }  
           return factors;  
      }  
 }  

Using Sieve of Eratosthenes

 About Sieve of Eratosthenes. This method is more faster than above prime number finding method.

 import java.util.*;  
 //create a structure  
 class list{  
      int value;  
      char flag;  
 }  
 public class ex{  
      public static void main(String args[]){  
           int integer;  
           Scanner scanner = new Scanner(System.in);  
           try{  
                System.out.print("\n\n\nEnter Integer : ");  
                //get integer  
                integer = scanner.nextInt();  
                if(integer==0){  
                     System.out.println("Error:Can not find primes for 0");  
                     System.exit(-1);  
                }  
                PrimesSieveOfEratosthenes(integer);  
           }catch(Exception e){  
                System.out.println("Error:Integer values must be given");  
           }  
      }  
      private static void PrimesSieveOfEratosthenes(int integer){  
           list integers[]=new list[integer];  
           //initialize list elements  
           for(int m=0;m<integers.length;m++){  
                integers[m]=new list();  
           }  
           //add values to list elements  
           for(int i=1;i<integer;i++){  
                integers[i].value=i+1;  
                integers[i].flag='0';  
           }  
           //find prime numbers  
           for(int k=2;k<=integer;k++){  
                if(integers[k-1].flag=='0'){  
                     for(int j=2*k-1;j<integer;j=j+k){  
                          integers[j].flag='1';  
                     }  
                }  
           }  
           //print prime numbers  
           for(int l=1;l<integer;l++){  
                if(integers[l].flag=='0'){  
                     System.out.print(integers[l].value+"\t");  
                }  
           }  
      }  
 }