为什么我的程序在输入后没有打印出来？

Question

Ok so I'm making a rock paper scissors program in java and I have all the code and it should give me the output I want but every time i run it it only prints out the input statement and nothing else. I made it print a line after the do loop that the input statement is located and it prints that but it doesn't print anything that's in the if statements and I don't quite understand why. This is what I have. Thank you for any help provided.

public static void main(String[] args) 
{
    Scanner input = new Scanner(System.in);
    Random rand = new Random();

    String replay = ("");
    String user = ("");
    int ai = 0;
    String aiPlay = ("");

    do
    {
        ai = rand.nextInt(3) + 1;

        switch (ai)    //was if statements but java suggested to change to switch statements
        {
            case 1:
                aiPlay = ("Rock");
                break;
            case 2:
                aiPlay = ("Paper");
                break;
            default:
                aiPlay = ("Scissors");
                break;
        }

        do   //make sure input is correct
        {
            System.out.print("rock, paper, or scissors: ");
            user = input.next();
        }while(!(user.equals("rock") || user.equals("paper") || user.equals("scissors")));

        if(user.equals(ai))
        {
        System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nIt was a tie!");
        System.out.print("Continue? (y or n): ");
        replay = input.next();
        }
        switch (user) {    //was if statements java suggested it change to switch statement 
            case "rock":
                if (aiPlay.equals("scissors"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou win!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }

                else if (aiPlay.equals("paper"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou lose!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }   break;
            case "paper":
                if (aiPlay.equals("scissors"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou win!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }

                else if (aiPlay.equals("rock"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou lose!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }   break;
            case "scissors":
                if (aiPlay.equals("paper"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou win!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }

                else if (aiPlay.equals("rock"))
                {
                    System.out.println("You played " + user + ".\nThe computer player " + aiPlay + ".\nYou lose!");
                    System.out.print("Continue? (y or n): ");
                    replay = input.next();
                }   break;
            default:
                break;
        }

    }while(replay.equals("y"));
}

Answer 1

switch (ai)    //was if statements but java suggested to change to switch 
statements
    {
        case 1:
            aiPlay = ("rock"); /* All should be lowercase*/ 
            break;
        case 2:
            aiPlay = ("paper"); /* All should be lowercase*/ 
            break;
        default:
            aiPlay = ("scissors"); /* All should be lowercase*/ 
            break;
    }