Primality by trial division

From Rosetta Code
Task
Primality by trial division
You are encouraged to solve this task according to the task description, using any language you may know.

Write a boolean function that tells whether a given integer is prime. Remember that 1 and all non-positive numbers are not prime.

Ada

function Is_Prime(Item : Positive) return Boolean is
   Result : Boolean := True;
   Test : Natural;
begin
   if Item /= 2 and Item mod 2 = 0 then
      Result := False;
   else
      Test := 3;
      while Test < Integer(Sqrt(Float(Item))) loop
         if Item mod Test = 0 then
            Result := False;
            exit;
         end if;
         Test := Test + 2;
      end loop;
  end if;
  return Result;
end Is_Prime;

Ruby

def prime(a)
  if a==2
   return true
  end

  if a<=1 || a%2==0
    return false
  end

  d=3
  while d <= Math.sqrt(a) do
    if a%d==0
      return false
    end
    d+=2
  end

return true
end

Java

public static boolean prime(long a){
   if(a == 2){
      return true;
   }else if(a <= 1 || a % 2 == 0){
      return false;
   }
   for(long n= 3; n <= (long)Math.sqrt(a); n+= 2){
      if(a % n == 0){ return false; }
   }
   return true;
}