exception on naming a class "var"

jcodemodel/src/main/java/com/helger/jcodemodel/JDefinedClass.java

@@ -177,7 +177,7 @@ public JCodeModel owner ()
     }
   };
 
-  protected JDefinedClass (@NonNull final IJClassContainer <?> aParent,
+  JDefinedClass (@NonNull final IJClassContainer <?> aParent,
                            final int nMods,
                            @Nullable final String sName,
                            @NonNull final EClassType eClassType)
@@ -195,7 +195,7 @@ protected JDefinedClass (@NonNull final IJClassContainer <?> aParent,
    * @param sName
    *        Name of this class
    */
-  protected JDefinedClass (@NonNull final JCodeModel aOwner, final int nMods, @Nullable final String sName)
+  JDefinedClass (@NonNull final JCodeModel aOwner, final int nMods, @Nullable final String sName)
   {
     this (aOwner, null, nMods, EClassType.CLASS, sName);
   }
@@ -214,7 +214,7 @@ protected JDefinedClass (@NonNull final JCodeModel aOwner, final int nMods, @Nul
    * @param sName
    *        Name of this class
    */
-  private JDefinedClass (@NonNull final JCodeModel aOwner,
+  JDefinedClass (@NonNull final JCodeModel aOwner,
                          @Nullable final IJClassContainer <?> aOuter,
                          final int nMods,
                          @NonNull final EClassType eClassType,
@@ -226,24 +226,8 @@ private JDefinedClass (@NonNull final JCodeModel aOwner,
     {
       ValueEnforcer.notEmpty (sName, "Name");
 
-      if (!Character.isJavaIdentifierStart (sName.charAt (0)))
-      {
-        final String msg = "JDefinedClass name " +
-                           sName +
-                           " contains illegal character" +
-                           " for beginning of identifier: " +
-                           sName.charAt (0);
-        throw new IllegalArgumentException (msg);
-      }
-      for (int i = 1; i < sName.length (); i++)
-      {
-        final char c = sName.charAt (i);
-        if (!Character.isJavaIdentifierPart (c))
-        {
-          final String msg = "JDefinedClass name " + sName + " contains illegal character " + c;
-          throw new IllegalArgumentException (msg);
-        }
-      }
+      if (!JJavaName.isTypeIdentifier (sName))
+        throw new IllegalArgumentException ("JDefinedClass name " + sName + " is invalid type name");
     }
 
     if (isInterface ())

jcodemodel/src/main/java/com/helger/jcodemodel/JJavaName.java

@@ -116,6 +116,20 @@ public static boolean isJavaIdentifier (@NonNull final String sStr)
     return true;
   }
 
+  /// verifies that a name is valid type identifier
+  ///
+  /// https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.8
+  ///
+  /// > A type identifier is an identifier that is not the character sequence var.
+  ///
+  /// > Type identifiers are used in certain contexts involving the declaration or use of types. For
+  /// > example, the name of a class must be a TypeIdentifier, so it is illegal to declare a class
+  /// > named var.
+  public static boolean isTypeIdentifier (@NonNull final String sStr)
+  {
+    return isJavaIdentifier (sStr) && !"var".equals (sStr);
+  }
+
   /**
    * Checks if the given string is a valid fully qualified name.
    *

jcodemodel/src/test/java/com/helger/jcodemodel/JDefinedClassTest.java

@@ -206,4 +206,16 @@ public void testEMods () throws JCodeModelException
     Assert.assertTrue (jdc.isEMod (EMod.SEALED, EMod.PRIVATE));
   }
 
+  @Test
+  public void testTypeNameVar () throws JCodeModelException
+  {
+    JCodeModel jcm = new JCodeModel ();
+    Assert.assertThrows (IllegalArgumentException.class, () -> new JDefinedClass (jcm, JMod.NONE, "double"));
+    Assert.assertThrows (IllegalArgumentException.class, () -> new JDefinedClass (jcm, JMod.NONE, "package"));
+    Assert.assertThrows (IllegalArgumentException.class, () -> new JDefinedClass (jcm, JMod.NONE, "var"));
+    new JDefinedClass (jcm, JMod.NONE, "Double");
+    new JDefinedClass (jcm, JMod.NONE, "Package");
+    new JDefinedClass (jcm, JMod.NONE, "Var");
+  }
+
 }