throw exception when tryng to add tag of different type to non-empty …

…untyped listtag
Querz · Sep 30, 2019 · b56ad64 · b56ad64
1 parent b80ee75
commit b56ad64
Show file tree

Hide file tree

Showing 2 changed files with 19 additions and 1 deletion.
diff --git a/src/main/java/net/querz/nbt/ListTag.java b/src/main/java/net/querz/nbt/ListTag.java
@@ -115,10 +115,16 @@ public void add(T t) {
 
 	public void add(int index, T t) {
 		Objects.requireNonNull(t);
-		getValue().add(index, t);
 		if (typeClass == null || typeClass == EndTag.class) {
 			typeClass = t.getClass();
+		} else if (typeClass != t.getClass()) {
+			throw new ClassCastException(
+					String.format("cannot add %s to ListTag<%s>",
+							t.getClass().getSimpleName(),
+							typeClass.getSimpleName()));
 		}
+		getValue().add(index, t);
+
 	}
 
 	public void addAll(Collection<T> t) {

diff --git a/src/test/java/net/querz/nbt/ListTagTest.java b/src/test/java/net/querz/nbt/ListTagTest.java
@@ -203,6 +203,18 @@ public void testCasting() {
 		assertEquals(lb, lg);
 		//only allow casting once from untyped list to typed list
 		assertThrowsRuntimeException(lg::asShortTagList, ClassCastException.class);
+
+		//adding generic Tags to an empty list
+		@SuppressWarnings("unchecked")
+		ListTag<Tag<?>> u = (ListTag<Tag<?>>) TagFactory.fromID(9);
+		assertEquals(EndTag.class, u.getTypeClass());
+		assertThrowsNoRuntimeException(() -> u.add(new StringTag()));
+		assertEquals(StringTag.class, u.getTypeClass());
+		assertThrowsRuntimeException(() -> u.add(new ByteTag()), ClassCastException.class);
+		assertThrowsNoRuntimeException(() -> u.add(new StringTag()));
+		assertEquals(2, u.size());
+
+
 	}
 
 	public void testCompareTo() {