org.apache.commons.lang3.ClassUtils.getCanonicalName(String) now throws

an IllegalArgumentException for array dimensions greater than 255

- No need to create strings over and over in a loop
- Preallocate string builder
- Javadoc since tag not needed for a private method

Author: garydgregory

src/changes/changes.xml

@@ -87,6 +87,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action                   type="fix" dev="ggregory" due-to="Gary Gregory">Reimplement StringUtils.toCodePoints(CharSequence) to use java.lang.CharSequence.codePoints().</action>
     <action                   type="fix" dev="ggregory" due-to="Gary Gregory">Reimplement StringUtils.capitalize(String) to use java.lang.CharSequence.codePoints().</action>
     <action                   type="fix" dev="ggregory" due-to="Gary Gregory">Reimplement StringUtils.uncapitalize(String) to use java.lang.CharSequence.codePoints().</action>
+    <action                   type="fix" dev="ggregory" due-to="Gary Gregory">org.apache.commons.lang3.ClassUtils.getCanonicalName(String) now throws an IllegalArgumentException for array dimensions greater than 255.</action>
     <action                   type="fix" dev="ggregory" due-to="Sridhar Balijepalli, Piotr P. Karwasz">Fix Javadoc typo and improve clarity in defaultIfBlank method #1376.</action>
     <!-- ADD -->
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add Strings and refactor StringUtils.</action>

src/main/java/org/apache/commons/lang3/ClassUtils.java

@@ -50,6 +50,11 @@
  */
 public class ClassUtils {
 
+    /**
+     * The maximum number of array dimensions.
+     */
+    private static final int MAX_DIMENSIONS = 255;
+
     /**
      * Inclusivity literals for {@link #hierarchy(Class, Interfaces)}.
      *
@@ -470,29 +475,32 @@ public static String getCanonicalName(final Object object, final String valueIfN
      * </ul>
      * </p>
      *
-     * @param className the name of class
-     * @return canonical form of class name
-     * @since 2.4
+     * @param className the name of class.
+     * @return canonical form of class name.
      */
     private static String getCanonicalName(final String name) {
         String className = StringUtils.deleteWhitespace(name);
         if (className == null) {
             return null;
         }
         int dim = 0;
-        while (className.startsWith("[")) {
+        while (className.charAt(dim) == '[') {
             dim++;
-            className = className.substring(1);
+            if (dim > MAX_DIMENSIONS) {
+                throw new IllegalArgumentException(String.format("Maximum array dimension %d exceeded", MAX_DIMENSIONS));
+            }
         }
         if (dim < 1) {
             return className;
         }
+        className = className.substring(dim);
         if (className.startsWith("L")) {
             className = className.substring(1, className.endsWith(";") ? className.length() - 1 : className.length());
         } else if (!className.isEmpty()) {
             className = reverseAbbreviationMap.get(className.substring(0, 1));
         }
-        final StringBuilder canonicalClassNameBuffer = new StringBuilder(className);
+        final StringBuilder canonicalClassNameBuffer = new StringBuilder(className.length() + dim * 2);
+        canonicalClassNameBuffer.append(className);
         for (int i = 0; i < dim; i++) {
             canonicalClassNameBuffer.append("[]");
         }

src/test/java/org/apache/commons/lang3/ClassUtilsTest.java

@@ -562,13 +562,13 @@ public void test_getShortCanonicalName_String() {
         assertEquals("int[][]", ClassUtils.getShortCanonicalName("[[I"));
         assertEquals("int[]", ClassUtils.getShortCanonicalName("int[]"));
         assertEquals("int[][]", ClassUtils.getShortCanonicalName("int[][]"));
-
         // this is to demonstrate that the documentation and the naming of the methods
         // uses the class name and canonical name totally mixed up, which cannot be
         // fixed without backward compatibility break
         assertEquals("int[]", int[].class.getCanonicalName());
         assertEquals("[I", int[].class.getName());
-
+        assertThrows(IllegalArgumentException.class, () -> ClassUtils.getShortCanonicalName(StringUtils.repeat("[", 256) + "I"));
+        assertEquals("int" + StringUtils.repeat("[]", 255), ClassUtils.getShortCanonicalName(StringUtils.repeat("[", 255) + "I"));
         // Inner types... the problem is that these are not canonical names, classes with this name do not even have canonical
         // name
         // WARNING: this is fragile, implementation may change, naming is not guaranteed