HiLo Guessing Game in Java

Many of you must have played HiLo game in your childhood. The game may be sort of similar to it if not exactly the same. It was fun, right?? So what if we are adults now? Let’s play this game once again in our own way. Let’s build a Java program for this and start playing this wonderful game HiLo.

1. What is HiLo Game?

In HiLo game, there are two simple rules:

• Guess the secret number in a maximum of 6 tries.
• The secret number is an integer between 1 and 100, Inclusive.

Everytime, you will guess a number below the secret number (only JRE knows it), “LO” will be printed. Similarly, when you guess a number higher than the secret number, “HI” will be printed. You have to adjust your next guess such that you are able to guess the right number within six attempts.

2. Solution

The following Java program reads the user inputs/guesses from the console and prints the messages to direct the user for the next step in the game.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Random;

public class HiLo {

  private final Random generator;
  private int generatedNumber;
  private int numberOfAttempts;
  BufferedReader reader = null;

  public HiLo() {
    generator = new Random();
    reader = new BufferedReader(new InputStreamReader(System.in));
  }

  public void start() throws IOException {

    boolean wantToPlay = false;
    boolean firstTime = true;

    do {
      System.out.println("\n\nWant to play the game of Hi and Lo??");

      if (wantToPlay = prompt()) {
        generatedNumber = generateSecretNumber();
        numberOfAttempts = 0;
        if (firstTime) {
          describeRules();
          firstTime = false;
        }
        playGame();
      }

    } while (wantToPlay);

    System.out.println("\nThanks for playing the game. Hope you loved it !!");
    reader.close();
  }

  private void describeRules() {

    System.out.println("\nOnly 2 Rules:");
    System.out.println("1) Guess the secret number in maximum 6 tries.");
    System.out.println("2) The secret number is an integer between 1 and 100, inclusive :-)\n\n");
  }

  private int generateSecretNumber() {
    return (generator.nextInt(100) + 1);
  }

  private void playGame() throws IOException {

    while (numberOfAttempts < 6) {

      int guess = getNextGuess();

      if (guess > generatedNumber) {
        System.out.println("HI");
      } else if (guess < generatedNumber) {
        System.out.println("LO");
      } else {
        System.out.println("Brave Soul, You guessed the right number!! Congratulations !!");
        return;
      }
      numberOfAttempts++;
    }

    System.out.println("Sorry, you didn't guess the right number in six attempts !!");
    System.out.println("The secret number was " + generatedNumber);

  }

  private boolean prompt() {

    boolean answer = false;

    try {

      boolean inputOk = false;
      while (!inputOk) {
        System.out.print("Y / N : ");
        String input = reader.readLine();
        if (input.equalsIgnoreCase("y")) {
          inputOk = true;
          answer = true;
        } else if (input.equalsIgnoreCase("n")) {
          inputOk = true;
          answer = false;
        } else {
          System.out.println(
              "Ohh come on. Even Mr. Bean knows where are 'y' and 'n' in the keyboard?? Please try again:");
        }
      }

    } catch (IOException e) {
      e.printStackTrace();
      System.exit(-1);
    }

    return answer;
  }

  private int getNextGuess() throws IOException {

    boolean inputOk = false;
    int number = 0;
    String input = null;
    while (!inputOk) {
      try {

        System.out.print("Please guess the secret number: ");
        input = reader.readLine();
        number = Integer.parseInt(input);
        if (number >= 1 && number <= 100) {
          inputOk = true;
        } else {
          System.out.println(
              "Really? You didn't read the rules boy. Your number is not between 1 and 100 ("
                  + number + ").");
        }
      } catch (NumberFormatException e) {
        System.out.println("Invalid input (" + input + ")");
      }
    }

    return number;
  }
}

3. Demo – Play the HiLo Game

Now, the game is ready. Let’s play it.

public class PlayHiLoGame {

  public static void main(String[] args) {
    
    HiLo hiLo = new HiLo();
    try {
      hiLo.start();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

The program output:

Want to play the game of Hi and Lo??
Y / N : y

Only 2 Rules:
1) Guess the secret number in maximum 6 tries.
2) The secret number is an integer between 1 and 100, inclusive.

Please guess the secret number: 40
LO
Please guess the secret number: 60
LO
Please guess the secret number: 80
HI
Please guess the secret number: 70
LO
Please guess the secret number: 75
LO
Please guess the secret number: 77
HI
Sorry, you didn't guess the right number in six attempts. In other two words, YOU LOST !!!!
The secret number was 76

Hope you enjoyed this game.

Happy Learning !!

Sourcecode on Github