How to Generate a Random Number Within a Fixed Range Excluding a Specific Number in Java

How can I generate a random number in Java within a fixed range while excluding a certain number?

// Example code to generate random number
int min = 1; // Minimum value
int max = 10; // Maximum value
int exclude = 5; // Number to exclude
Random random = new Random();
int randomNumber;
do {
    randomNumber = random.nextInt((max - min) + 1) + min;
} while (randomNumber == exclude); // Retry if the number is excluded
System.out.println("Generated random number: " + randomNumber);

Generating a random number in Java within a specific range and excluding a certain number can be efficiently achieved using the Random class. This process involves generating random numbers until the generated number differs from the excluded one. Here's how you can implement this approach:

import java.util.Random;

public class RandomNumberExclusion {
    public static void main(String[] args) {
        int min = 1; // Define minimum value
        int max = 10; // Define maximum value
        int exclude = 5; // Define the number to exclude
        Random random = new Random();
        int randomNumber;
        do {
            randomNumber = random.nextInt((max - min) + 1) + min;
        } while (randomNumber == exclude);
        System.out.println("Generated random number: " + randomNumber);
    }
}

Causes

• To ensure diversity in random number generation.
• To avoid returning a specific value that may not be desired in the context.

Solutions

• Use a loop to keep generating random numbers until the excluded number is bypassed.
• Clearly define your ranges and exclusions.
• Make sure to handle edge cases where the range is very small.

Mistake: Not handling edge cases when range is too small (e.g., min = 1, max = 2, excluding 1).

Solution: Ensure your range contains at least two distinct numbers if one is to be excluded.

Mistake: Using a fixed seed in Random which results in the same sequence of random numbers.

Solution: Remove the fixed seed or randomize it to allow for true randomness.