Java

So I'm writing a Rock Papper Scissors program for my programming class.

/*
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package lab4;

/**
 *
 * @author LAPPY
 */
// ****************************************************************
//   Rock.java
//
//   Play Rock, Paper, Scissors with the user
//
// ****************************************************************
import java.util.Scanner;
import java.util.Random;

public class Rock
{
    public static void main(String[] args)
    {
    String personPlay;    //User's play -- "R", "P", or "S"

    String computerPlay = null;  //Computer's play -- "R", "P", or "S"
                          //Randomly generated number used to determine
    int computerInt;      //Randomly generated number used to determine
                          //computer's play

        Scanner scan = new Scanner(System.in);
    Random generator = new Random();




    computerInt = generator.nextInt (3); //Generate computer's play (0,1,2)





    //Translate computer's randomly generated play to string
    switch (computerInt)


        {
            case 0:
                computerPlay = "R";
                break;
            case 1:
                computerPlay = "P";
                break;
            case 2:
                computerPlay = "S";
                break;

    }


        //Get player's play from input-- note that this is stored as a string
        System.out.println ("Enter your play: R, P, or S");

        personPlay = scan.nextLine();



    //Make player's play uppercase for ease of comparison
        personPlay.toUpperCase();



    //Print computer's play
        System.out.println ("Computer play is " + computerPlay);



    //See who won.  Use nested ifs instead of &&.
    if (personPlay.equals(computerPlay))
        System.out.println("It's a tie!");
    else if (personPlay.equals("R"))
        if (computerPlay.equals("S"))
        System.out.println("Rock crushes scissors.  You win!!");
            else if(computerPlay.equals("P"))
                System.out.println("Paper covers rock. You lose!!");
        if(personPlay.equals("P"))
            if (computerPlay.equals("S"))
                System.out.println("Scissors cut paper. You lose!!");
            else if(computerPlay.equals("R"))
                System.out.println("Paper covers rock. You win!!");
       if (personPlay.equals("S"))
            if (computerPlay.equals("R"))
                System.out.println("Rock crushes scissors.  You lose!!");
            else if(computerPlay.equals("P"))
                System.out.println("Scissors cut paper. You win!!");


    }
}

The problem is, the "personPlay.toUpperCase();" won't do anything at all. I have to enter an uppercase letter as if that command isn't there.

What am I missing?

Disregard that, I figured it out.

I was supposed to "personPlay = personPlay.toUpperCase();"