Probability of x possible outcomes [duplicate]

Answer 1

Here's one way to do it.

public static String getOutcome(Map possibilities) {
    int x = (int) (Math.random() * 100);

    for (Map.Entry possibility : possibilities.entrySet()) {
        if (x <= possibility.getValue()) {
            return possibility.getKey();
        }
        x -= possibility.getValue();
    }

    // unreachable if probabilities are correctly mapped
    return null;
}