Thread: Loop Help

The logic of my program works. I am having a hard time asking the user "do you want to do another? yes or no." and user would type yes or no, for the scanner class to read as a string. If the user types yes the program will start over if the user says no the program will say " Thanks for playing." I got it to print " Do you want to do another? yes or no" and used a scanner class. However the scanner class is not working. Can anyone help me... THanks in advance.

 import java.util.Scanner;
 public class test4 
{ 
	public static void main (String[] args)
	{
		Scanner scan = new Scanner (System.in);
 
		int userNum, total, addNum = 0, totalNum;
		String play = "yes";
 
		while ( play == "yes" && play != "no") 
		{
			System.out.println("Enter a number that is 3 or higher.");
			userNum = scan.nextInt(); 
 
			if (userNum >= 3)
			{
				for(int count = 3; count<userNum; count +=2)
				{
					addNum = addNum + count;
				}
				System.out.println("The sum of the ODD integers from 3 to " + userNum +  " is " + addNum);
				System.out.println(" ");
				System.out.println ("Do you want to do another? yes or no");
				play = scan.nextLine( );
			}
 
 
			if(userNum < 3)
			{
				System.out.println("Error: The value must be greater than two");
				System.out.println(" ");
			}
		}
		while (play == "no")
		{
			System.out.println("Thanks Good Bye.");
		}	
	}
}