Avoid NullPointerException in IOCase.checkIndexOf(String, int, String)

on null input

Author: garydgregory

src/changes/changes.xml

@@ -72,6 +72,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in FileFileFilter.accept(Path, BasicFileAttributes) on null input.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in HiddenFileFilter.accept(File) on null input.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in HiddenFileFilter.accept(Path, BasicFileAttributes) on null input.</action>
+      <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in IOCase.checkIndexOf(String, int, String) on null input.</action>
       <!-- Add -->
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Add and use PathUtils.getFileName(Path, Function&lt;Path, R&gt;).</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Add and use PathUtils.getFileNameString().</action>

src/main/java/org/apache/commons/io/IOCase.java

@@ -185,15 +185,16 @@ public boolean checkEquals(final String str1, final String str2) {
      * @param search  the start to search for, not null
      * @return the first index of the search String,
      *  -1 if no match or {@code null} string input
-     * @throws NullPointerException if either string is null
      * @since 2.0
      */
     public int checkIndexOf(final String str, final int strStartIndex, final String search) {
-        final int endIndex = str.length() - search.length();
-        if (endIndex >= strStartIndex) {
-            for (int i = strStartIndex; i <= endIndex; i++) {
-                if (checkRegionMatches(str, i, search)) {
-                    return i;
+        if (str != null && search != null) {
+            final int endIndex = str.length() - search.length();
+            if (endIndex >= strStartIndex) {
+                for (int i = strStartIndex; i <= endIndex; i++) {
+                    if (checkRegionMatches(str, i, search)) {
+                        return i;
+                    }
                 }
             }
         }

src/test/java/org/apache/commons/io/IOCaseTest.java

@@ -152,6 +152,9 @@ public void test_checkEquals_functionality() {
     public void test_checkIndexOf_case() {
         assertEquals(1,  IOCase.SENSITIVE.checkIndexOf("ABC", 0, "BC"));
         assertEquals(-1, IOCase.SENSITIVE.checkIndexOf("ABC", 0, "Bc"));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf(null, 0, "Bc"));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf(null, 0, null));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf("ABC", 0, null));
 
         assertEquals(1, IOCase.INSENSITIVE.checkIndexOf("ABC", 0, "BC"));
         assertEquals(1, IOCase.INSENSITIVE.checkIndexOf("ABC", 0, "Bc"));
@@ -199,9 +202,9 @@ public void test_checkIndexOf_functionality() {
         // too long
         assertEquals(-1,   IOCase.SENSITIVE.checkIndexOf("DEF", 0, "ABCDEFGHIJ"));
 
-        assertThrows(NullPointerException.class, () -> IOCase.SENSITIVE.checkIndexOf("ABC", 0, null));
-        assertThrows(NullPointerException.class, () -> IOCase.SENSITIVE.checkIndexOf(null, 0, "ABC"));
-        assertThrows(NullPointerException.class, () -> IOCase.SENSITIVE.checkIndexOf(null, 0, null));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf("ABC", 0, null));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf(null, 0, "ABC"));
+        assertEquals(-1, IOCase.SENSITIVE.checkIndexOf(null, 0, null));
     }
 
     @Test