String s = "This is to test charAt()";
CharBuffer c = CharBuffer.wrap(s.toCharArray());
c.position(8);
c.charAt(-1);

compiles and runs without throwing IndexOutOfBoundsException exception, for index < 0.

###@###.### 2001-10-04
java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b82)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b82, mixed mode)

/net/sqesvr/export/xlt/libs/merlin/dev/testbase/src/libs_api_tests/common/java_nio/Buffer/CharBufferTest/CBCharAt 6 % java CBCharAt
Total tests for Exec : 1
Expected IndexOutOfBoundsException thrown for index < 0
Expected IndexOutOfBoundsException thrown for index > remaining()
Expected IndexOutOfBoundsException thrown for index > limit()
Pass count: 1
Fail count: 0
Test for CharAt.java Passed