envoy/src/main/java/envoy/data/IdGenerator.java

package envoy.data;

import java.io.Serializable;

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

	private final long	end;
	private long		current;

	private static final long serialVersionUID = -1517378307055845147L;

	/**
	 * Creates an instance of {@link IdGenerator}.
	 *
	 * @param begin the first ID
	 * @param size  the amount of IDs to provide
	 * @since Envoy Common v0.2-alpha
	 */
	public IdGenerator(long begin, long size) {
		current	= begin;
		end		= begin + size;
	}

	@Override
	public String toString() { return String.format("IdGenerator[current=%d,end=%d]", current, 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++;
	}
}