[GitHub] [commons-lang] aherbert commented on a change in pull request #727: LANG-1644 - Check if number is hexadecimal

[GitBox <gi...@apache.org>]

aherbert commented on a change in pull request #727:
URL: https://github.com/apache/commons-lang/pull/727#discussion_r586910342



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File path: src/main/java/org/apache/commons/lang3/math/NumberUtils.java
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@@ -1715,6 +1715,50 @@ public static boolean isCreatable(final String str) {
         return !allowSigns && foundDigit;
     }
 
+    /**
+     * Checks whether the given String is a hex number.
+     *
+     * <p>Valid parameter include hexadecimal marked with the {@code 0x} or
+     * {@code 0X} qualifier.</p>
+     *
+     * <p>{@code Null} and empty String will return {@code false}.</p>
+     *
+     * <pre>
+     * NumberUtils.isHexNumber(null))                 = false
+     * NumberUtils.isHexNumber(""))                   = false
+     * NumberUtils.isHexNumber("0x12345678"))         = true
+     * NumberUtils.isHexNumber("0x7fffffffffffffff")) = true
+     * NumberUtils.isHexNumber("0x7FFFFFFFFFFFFFFF")) = true
+     * NumberUtils.isHexNumber("5D0"))                = true
+     * NumberUtils.isHexNumber("0x"))                 = false
+     * </pre>
+     *
+     * @param str the String to check.
+     * @return {@code true} if the string is a hex number.
+     * @since 3.12.1
+     */
+    public static boolean isHexNumber(final String str) {
+        if (StringUtils.isEmpty(str)) {
+            return false;
+        }
+        final char[] chars = str.toCharArray();
+        final int length = chars.length;
+        int i = 1;
+        if (chars[i] == 'x' || chars[i] == 'X') {

Review comment:
       If chars is length 1 then this will throw an index out of bounds exception.




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