Guess a random number between a selected interval

Question

My project for my class is to create a Java-based game where the user must enter a number between 1-20 and a number between 250 and 300. The computer randomly chooses a number between those 2 numbers. Then the user has 10 guesses to correctly guess what number the computer is "thinking of."

There is a catch, though. We cannot use while loops, only if and else-if statements. I have started this code and was wondering if I'm on the right track. Please point out anything that might help me!

package guessthenumber;
import java.util.Scanner;
import java.util.Random;
public class GuessTheNumber {
 public static void main(String[] args) 
 {
 int lowBoundary, highBoundary, secretNumber, boundaryDifference,
 g1, g2, g3, g4, g5, g6, g7, g8, 
 g9, g10;
 //g1, g2,... = guess 1, guess2,...
 Scanner keyboard = new Scanner(System.in);
 System.out.println("Can you guess the number I'm thinking of?\nLet's "
 + "see if you can guess the right number within 10 guesses.\n\n"
 + "First please enter a number between 1 and 20.");
 lowBoundary = keyboard.nextInt();
 System.out.println("Excellent! Next enter a number between 250 and "
 + "350.");
 highBoundary = keyboard.nextInt();
 boundaryDifference = highBoundary - lowBoundary;
 Random randomNumber = new Random();
 secretNumber = randomNumber.nextInt(boundaryDifference) + lowBoundary;
 System.out.println("The secret number has been chosen. Now you must "
 + "guess\nthe secret number within 10 guesses or else you lose."
 + "\n(Hint: The secret number is between " + lowBoundary +
 " and " + highBoundary + ".)");
 g1 = keyboard.nextInt();
 if (g1 == secretNumber) {
 System.out.println("CONGRATULATIONS! YOU'VE CORRECTLY GUESSED\nTHE"
 + "SECRET NUMBER ON YOUR FIRST GUESS!!");
 } 
 else if (g1 < secretNumber) {
 System.out.println("Higher than " + g1 + ". Guess again!");
 g2 = keyboard.nextInt();
 {
 if (g2 == secretNumber) {
 System.out.println("Awesome! You've correctly guessed\nthe"
 + "secret number in 2 guesses!");
 }
 else if (g2 < secretNumber) {
 System.out.println("Higher than " + g2 + ". Guess again!");
 g3 = keyboard.nextInt();
 if (g3 == secretNumber) {
 System.out.println("Great job! You've correctly guessed\n"
 + "the secert number in 3 guesses!");
 }
 else if (g3 < secretNumber) {
 System.out.println("Higher than " + g3 + ". Guess again!");
 g4 = keyboard.nextInt();
 if (g4 == secretNumber) {
 System.out.println("Good job! You've correctly guessed\nthe"
 + " secret number in 4 guesses!");
 }
 else if (g4 < secretNumber) {
 System.out.println("Higher than " + g4 + ". Guess again!");
 g5 = keyboard.nextInt();
 if (g5 == secretNumber) {
 System.out.println("Not bad! You've correctly guessed\nthe"
 + " secret number in 5 guesses!");
 }
 else if (g4 > secretNumber) {
 System.out.println("Lower than " + g4 + ". Guess again!");
 }
 }
 }
 else if (g3 > secretNumber) {
 System.out.println("Lower than " + g3 + ". Guess again!");
 }
 }
 else if (g2 > secretNumber) {
 System.out.println("Lower than " + g2 + ". Guess again!"
 );
 g3 = keyboard.nextInt();
 }
 }
 }
 else if (g1 > secretNumber) {
 System.out.println("Lower than" + g1 + ". Guess again!");
 {
 }
 }
 }
}

Answer 1

I'm guessing you're not allowed to use any kind of loop, because then you could just use a for-loop.

Anyhow, I would suggest you encapsulate more of your code in methods. Think about what kind of operations you use repeatedly.

Also, you don't need multiple guessing variables (g1, g2, g3, ... , g10); you can make do with one.

Now to solve the main problem. I would suggest using a recursive method (a method that calls for itself). It can very well act as a loop and you could, for example, count the guesses with it among other things.

Here's an example of a recursive method that returns the sum of all integers from 1 up to a given number:

public static int sumIntegers(int number){
 if (number == 1)
 return number;
 return number + sumIntegers(number - 1);
}

If you would call this method like this:

sumIntegers(5);

You would get: 5 +たす 4 +たす 3 +たす 2 +たす 1 =わ 15

Hope it helps!

• Simon Forsberg: +1 for giving a push in the right direction without revealing too much (considering the homework tag on the question)

Answer 2

This code is somewhat broken (slightly):

 boundaryDifference = highBoundary - lowBoundary;
 Random randomNumber = new Random();
 secretNumber = randomNumber.nextInt(boundaryDifference) + lowBoundary;

This is one of the most common duplicate problems on StackOverflow, and it's a lesson you should just learn....

The above code will never produce the value 'highBoundary`.

This is because nextInt(boundaryDifference) produces a result from 0 to boundaryDistance excluding boundaryDistance.

The right way to get a random number from a given range including both limits of the range is:

 int val = min + randomNumber.nextInt((max - min) + 1);

Never forget the +1