\n * If count or length is zero then the empty string is returned.\n *
\n * This method may be used to create space padding for\n * formatting text or zero padding for formatting numbers.\n *\n * @param count number of times to repeat\n *\n * @return A string composed of this string repeated\n * {@code count} times or the empty string if count\n * or length is zero.\n *\n * @throws IllegalArgumentException if the {@code count} is negative.\n * @link https://bugs.openjdk.java.net/browse/JDK-8197594\n */\n public static String repeat(String s, int count)\n {\n if (count < 0) {\n throw new IllegalArgumentException(\"count is negative, \" + count);\n }\n if (count == 1) {\n return s;\n }\n byte[] value = s.getBytes(StandardCharsets.UTF_8);\n final int len = value.length;\n if (len == 0 || count == 0) {\n return \"\";\n }\n if (len == 1) {\n final byte[] single = new byte[count];\n Arrays.fill(single, value[0]);\n return new String(single, StandardCharsets.UTF_8);\n }\n if (Integer.MAX_VALUE / count < len) {\n throw new RuntimeException(\"The produced string is too large.\");\n }\n final int limit = len * count;","sourceCodeStart":590,"sourceCodeEnd":626,"githubUrl":"https://github.com/apache/druid/blob/9b90983fd291f26935af934383ce360473179e4d/processing/src/main/java/org/apache/druid/java/util/common/StringUtils.java#L590-L626","documentation":"StringUtils.repeat(String, int) repeats a string a given number of times. It throws IllegalArgumentException when count is negative, mirroring the commons-lang behavior it replaces (JDK-8197594 workaround). A negative repeat count is meaningless and treated as a caller bug.","triggerScenarios":"Calling StringUtils.repeat(s, n) with n < 0 — typically when n comes from user input, computed padding widths (e.g. length difference), or unvalidated config.","commonSituations":"Formatting/padding code computing count as (targetLength - actualLength) when the string is already longer than target; SQL LPAD-like expressions with negative length parameters.","solutions":["Clamp the count before calling: Math.max(0, count).","Validate user/config-supplied lengths before passing them.","Catch IllegalArgumentException and return \"\" for negative counts.","Fix the computation so the difference is never negative (guard the subtraction)."],"exampleFix":"// before\nString pad = StringUtils.repeat(\" \", width - s.length());\n// after\nString pad = StringUtils.repeat(\" \", Math.max(0, width - s.length()));","handlingStrategy":"validation","validationCode":"if (count < 0) { throw new IllegalArgumentException(\"repeat count must be >= 0, got \" + count); }","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Always clamp computed repeat counts with Math.max(0, n)","Validate user/config-supplied lengths before formatting","Guard padding math (targetLen - len) against negative results"],"tags":["string-utils","illegal-argument","negative-value"],"backgroundTag":"invalid-argument-value","analyzedSha":"9b90983fd291f26935af934383ce360473179e4d","analyzedAt":"2026-09-07T13:32:30.957Z","contentChangedAt":"2026-09-07T13:32:30.957Z","schemaVersion":2},"datasetVersion":"2026-09-17T15:17:12.973Z"}