title: Java String Method returning Null?
body: <p>I was tasked with making a simple program that will play Rock-Paper-Scissors with the user. Unfortunately, when I try to run the program, my return(sentence+outcome) both returns null. I am new to using methods, so please explain what I am doing wrong here... Thank you!</p>
  
  <pre><code> package rockpaperscissors;
  
  /**
   *
   * @author Owner
   */
  import java.util.Scanner;
  import java.io.IOException;
  
  public class RockPaperScissors {
  
      static int weaponChoice;
      static int computerChoice;
      static int tie = 0;
      static int lose = 0;
      static int win = 0;
      static String outcome;
      static String sentence;
  
      /**
       * @param args the command line arguments
       * @throws java.io.IOException
       */
      public static void main(String[] args) throws IOException {
          Scanner userInput = new Scanner(System.in);
          System.out.println(" =========================");
          System.out.println("====ROCK=PAPER=SCISSORS====");
          System.out.println(" =========================");
          int playAgain = 1; //sets a play again function
          do {
              System.out.println("Please select your weapon.");
              System.out.println("1 - Rock");
              System.out.println("2 - Paper");
              System.out.println("3 - Scissors");
              System.out.println("Choose wisely:");
              String choice = userInput.nextLine();
              weaponChoice = Integer.parseInt(choice);
              do {
                  if (weaponChoice != 1 &amp;&amp; weaponChoice != 2 &amp;&amp; weaponChoice != 3) {
                      System.out.println("Please choose again, grasshopper. There are only"
                              + " three choices.");
                      System.out.println("1 - Rock");
                      System.out.println("2 - Paper");
                      System.out.println("3 - Scissors");
                      choice = userInput.nextLine();
                      weaponChoice = Integer.parseInt(choice);
                  }
              } while (weaponChoice != 1 &amp;&amp; weaponChoice != 2 &amp;&amp; weaponChoice != 3);
  
              if (weaponChoice == 1) {
                  System.out.println("You have selected Rock as your weapon.");
              } else if (weaponChoice == 2) {
                  System.out.println("You have selected Paper as your weapon.");
              } else {
                  System.out.println("You have selected Scissors as your weapon.");
              }
              //Computer's Choice
              computerChoice = 1 + (int) (Math.random() * ((3 - 1) + 1));
              if (computerChoice == 1) {
                  System.out.println("The computer has chosen Rock.");
              } else if (computerChoice == 2) {
                  System.out.println("The computer has chosen Paper.");
              } else {
                  System.out.println("The computer has chosen Scissors.");
              }
   determineOutcome(outcome, sentence);
              System.out.println(sentence+outcome);
              System.out.println("==SCORES==");
              System.out.println("WINS: " + win);
              System.out.println("TIES: " + tie);
              System.out.println("LOSSES: " + lose);
              System.out.println("Press 1 to play again, or any other number to exit.");
              String play = userInput.nextLine();
              playAgain = Integer.parseInt(play);
          } while (playAgain == 1);
      }
  
      public static String determineOutcome(String outcome, String sentence) {
  sentence = "Your result is: ";
          do {
              if (weaponChoice == 1 &amp;&amp; computerChoice == 1 || weaponChoice == 2 &amp;&amp; computerChoice == 2 || weaponChoice == 3 &amp;&amp; computerChoice == 3) {
                  tie++;
                  outcome = "TIE";
              } else if (weaponChoice == 1 &amp;&amp; computerChoice == 3 || weaponChoice == 2 &amp;&amp; computerChoice == 1 || weaponChoice == 3 &amp;&amp; computerChoice == 2) {
                  win++;
                  outcome = "You WON!";
              } else {
                  lose++;
                  outcome = "You LOSE. Better luck next time?";
              }
          } while (lose &lt;0 || win &lt; 0 || tie &lt; 0);
          return(sentence+outcome);
      } 
  }
  </code></pre>