MPGConstraint.java

package com.discursive.cjcook.guava.collect;

import com.google.common.collect.Constraint;

public class MPGConstraint implements Constraint<Automobile> {

	private Integer minimumMPG;

	public MPGConstraint(int minimumMPG) {
		this.minimumMPG = minimumMPG;
	}

	@Override
	public Automobile checkElement(Automobile element) {
		if (element.getMilesPerGallon() != null
				&& element.getMilesPerGallon() < minimumMPG) {
			throw new IllegalArgumentException(
					"Automobile does not meet minimum fuel standards");
		}
		return element;
	}
}