Assignemnt #Final and Final Exam Coin Flip

Code

    ///Name: Daniel Tiffany-Appleton
    ///Period: 7
    ///Program Name: Final Exam Coin Flip
    ///File Name: FinalExamCoinFlip
    ///Date Finished: 1/21/16
    
    import java.util.Random;
    import java.util.Scanner;
    
    public class FinalExamCoinFlip
    {
        public static void main ( String[] args )
        {
            
        Random r = new Random();
        Scanner keyboard = new Scanner(System.in);
        
        int flips, numberOfHeads, numberOfTails, coinFlips, outcome;// I used flips and coinFlips so the while loops knows to where to stop.
        double probablityOfHeads, probabilityOfTails;
        
        System.out.print( "How many times to you want me to flip the coin: ");
        flips = keyboard.nextInt();
        
        if( 0 >= flips )//I used ifs here so if a bad number is used then the program will end and state the words in the brackets.
        {
            System.out.println( "ERROR! Number impossible to use.");
            System.out.print( "How many times to you want me to flip the coin: ");
            flips = keyboard.nextInt();
        }
           
        else if(flips > 2100000000)
        {
            System.out.println( "ERROR! Number impossible to use.");
            System.out.print( "How many times to you want me to flip the coin: ");
            flips = keyboard.nextInt();
        }
            
        numberOfHeads = 0;
        numberOfTails = 0;
        coinFlips = 0;
        
        while(coinFlips != flips) //I used a while loop so flips and the outcomes can be checked before the coin is flipped.
        {
            outcome = r.nextInt(2);
            
            if( outcome == 0 )
            {
                numberOfHeads++;
            }
            
            else if( outcome == 1 )
            {
                numberOfTails++;
            }
            
            coinFlips++;
        }
          
        probablityOfHeads = (double)numberOfHeads / flips;
        probabilityOfTails = (double)numberOfTails / flips;
        
        System.out.println(" "); 
        System.out.println( "Number of Heads: " + numberOfHeads + ". Probability of landing on Heads: " + probablityOfHeads + ".");
        
        System.out.println(" ");
        System.out.println( "Number of Tails: " + numberOfTails + ". Probability of landing on Heads: " + probabilityOfTails + ".");
        System.out.println(" ");
        
        }
    }
    //The best number 21000000 because it is the highest number that the computer can use and this number will get to the closest 50/50 because it will even out and little variations will not show up. 
    
    

Picture of the output