src/java.base/share/classes/java/lang/String.java

rev 55936 : [mq]: 8221307-String-substring-OOB-exception-on-start-index-reports-improper-information

@@ -1866,20 +1866,21 @@
      * @exception  IndexOutOfBoundsException  if
      *             {@code beginIndex} is negative or larger than the
      *             length of this {@code String} object.
      */
     public String substring(int beginIndex) {
-        if (beginIndex < 0) {
-            throw new StringIndexOutOfBoundsException(beginIndex);
-        }
         int subLen = length() - beginIndex;
-        if (subLen < 0) {
-            throw new StringIndexOutOfBoundsException(subLen);
-        }
+        if (beginIndex <= 0 || subLen <= 0) {
         if (beginIndex == 0) {
             return this;
         }
+            if (subLen == 0) {
+                return "";
+            }
+            throw new StringIndexOutOfBoundsException(
+                "begin " + beginIndex + ", length " + length());
+        }
         return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen)
                           : StringUTF16.newString(value, beginIndex, subLen);
     }
 
     /**