Question

I am receiving an error with this code that pops up Class file editor: source not found inside the Random.class tab. It was having issues with my line that says value =…

I am trying to create a general method the generate a random number between the two integers I pass in.

import java.util.Random;

public class RandomNumGen {

    int value;
    Random rand;
    public RandomNumGen() {
        rand = new Random();
    }

    public int intRandom(int min, int max) {
        value = rand.nextInt(max) + min;
        return(value);
    }

    public int choiceRandom(int first, int second, int third, int fourth) {
        int random = intRandom(1, 400);
        if (random < 100) {
            return(first);
        }else if (random > 100 && random < 200) {
            return(third);
        }else if (random > 200 && random < 300) {
            return(fourth);
        }
        return(second);
    }
}

Help would be appreciated,

Thanks

Answer 1

The “source not found” error is because it tried to open the source to java.util.Random to help you debug and couldn’t find it. The code looks right in that it should execute without errors; Random.nextInt will throw an IllegalArgumentException if you pass it a non-positive number, but you’re passing it 400. I don’t get any errors running that code snippet and calling choiceRandom(1, 2, 3, 4);

However, logically the code is wrong — intRandom doesn’t return a number between min and max. You’re calling nextInt(max), which returns a number between 0 and max-1, and then adding min, making the range between min and min+max-1. You’d need to return rand.nextInt(max-min) + min

If you just want a method that takes a bunch of integers and returns one at random, a simpler implementation is:

public int choiceRandom(int... numbers) {
    return numbers[rand.nextInt(numbers.length)];
}