General code refactoring and maintenance

1 files changed, 4 insertions, 0 deletions

diff --git a/BJC-Utils2/src/main/java/bjc/utils/gen/RandomGrammar.java b/BJC-Utils2/src/main/java/bjc/utils/gen/RandomGrammar.java
index ca0578d..4f194f3 100644
--- a/BJC-Utils2/src/main/java/bjc/utils/gen/RandomGrammar.java
+++ b/BJC-Utils2/src/main/java/bjc/utils/gen/RandomGrammar.java
@@ -62,6 +62,10 @@ public class RandomGrammar<E> extends WeightedGrammar<E> {
 	 *            The cases to add for this rule.
 	 */
 	public void makeRule(E rule, FunctionalList<FunctionalList<E>> cases) {
+		if (cases == null) {
+			throw new NullPointerException("Cases must not be null");
+		}
+
 		super.addRule(rule);
 
 		cases.forEach(currentCase -> super.addCase(rule, 1, currentCase));