envoy/src/main/java/envoy/data/MessageIdGenerator.java

package envoy.data;

/**
 * Generates increasing IDs between two numbers.<br>
 * <br>
 * Project: <strong>envoy-common</strong><br>
 * File: <strong>MessageIdGenerator.java</strong><br>
 * Created: <strong>31.12.2019</strong><br>
 * 
 * @author Kai S. K. Engelbart
 * @since Envoy Common v0.2-alpha
 */
public class MessageIdGenerator {

	private final long	end;
	private long		current;

	/**
	 * Creates an instance of {@link MessageIdGenerator}.
	 *
	 * @param begin the first ID
	 * @param end   the last ID
	 * @since Envoy Common v0.2-alpha
	 */
	public MessageIdGenerator(long begin, long end) {
		current		= begin;
		this.end	= end;
	}

	/**
	 * @return {@code true} if there are unused IDs remaining
	 * @since Envoy Common v0.2-alpha
	 */
	public boolean hasNext() { return current < end; }

	/**
	 * @return the next ID
	 * @since Envoy Common v0.2-alpha
	 */
	public long next() {
		if (!hasNext()) throw new IllegalStateException("All IDs have been used");
		return current++;
	}
}