net.aequologica.neo.shakuntala.UUIDHolder Maven / Gradle / Ivy

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package net.aequologica.neo.shakuntala;

import java.util.UUID;

public final class UUIDHolder {

    private UUID uuid;

    public UUID get() {
        return this.uuid;
    }

    public void setOnce(UUID uuid) {
        if (this.uuid != null) {
            return;
        }
        this.uuid = uuid;
    }

    // 'hand-made' singleton
    // cf. https://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom
    // for the singleton pattern used
    // maybe someday, we'll understand enough CDI with maven to remove that shit

    private UUIDHolder() {
    }

    private static class LazyUUIDHolderHolder {
        private static final UUIDHolder INSTANCE = new UUIDHolder();
    }

    public static UUIDHolder getInstance(UUID uuid) {
        return LazyUUIDHolderHolder.INSTANCE;
    }

    public static UUIDHolder getInstance() {
        return LazyUUIDHolderHolder.INSTANCE;
    }

}