A string object contains a sequence of characters that cannot be changed. When you attempt to "modify" a String object, a new String Object is actually created. This is inefficient when the sequence of characters is frequently modified. The solution is to use a StringBuffer object so that changes in the sequence of characters does not require the creation of a new object.
SCJP 1.4 - 93%
SCWCD 1.4 - 89%
IBM FileNet 3.5 - Developer
IBM FileNet 3.5 - Administrator