diff -U 5 -r defects4j/Lang-20/buggy/src/main/java/org/apache/commons/lang3/StringUtils.java defects4j/Lang-20/fixed/src/main/java/org/apache/commons/lang3/StringUtils.java
--- defects4j/Lang-20/buggy/src/main/java/org/apache/commons/lang3/StringUtils.java     2024-04-14 01:08:54.000000000 +0900
+++ defects4j/Lang-20/fixed/src/main/java/org/apache/commons/lang3/StringUtils.java     2024-04-14 01:09:03.000000000 +0900
@@ -3293,11 +3293,11 @@
         int noOfItems = (endIndex - startIndex);
         if (noOfItems <= 0) {
             return EMPTY;
         }

-        StringBuilder buf = new StringBuilder((array[startIndex] == null ? 16 : array[startIndex].toString().length()) + 1);
+        StringBuilder buf = new StringBuilder(noOfItems * 16);

         for (int i = startIndex; i < endIndex; i++) {
             if (i > startIndex) {
                 buf.append(separator);
             }
@@ -3378,11 +3378,11 @@
         int noOfItems = (endIndex - startIndex);
         if (noOfItems <= 0) {
             return EMPTY;
         }

-        StringBuilder buf = new StringBuilder((array[startIndex] == null ? 16 : array[startIndex].toString().length()) + separator.length());
+        StringBuilder buf = new StringBuilder(noOfItems * 16);

         for (int i = startIndex; i < endIndex; i++) {
             if (i > startIndex) {
                 buf.append(separator);
             }