RFR (JDK11) 8137326: Methods for comparing CharSequence, StringBuilder, and StringBuffer

[Joe Wang]

Hi,

Adding methods for comparing CharSequence, StringBuilder, and StringBuffer.

The Comparable implementations for StringBuilder/Buffer are similar to 
that of String, allowing comparison operations between two 
StringBuilders/Buffers, e.g. 
aStringBuilder.compareTo(anotherStringBuilder). For CharSequence 
however, refer to the comments in JIRA, a static method 'compare' is 
added instead of implementing the Comparable interface. This 'compare' 
method may take CharSequence implementations such as String, 
StringBuilder and StringBuffer, making it possible to perform comparison 
among them. The previous example for example is equivalent to 
CharSequence.compare(aStringBuilder, anotherStringBuilder).

Tests for java.base have been independent from each other. The new tests 
are therefore created to have no dependency on each other or sharing any 
code.

JBS: https://bugs.openjdk.java.net/browse/JDK-8137326
webrev: http://cr.openjdk.java.net/~joehw/jdk11/8137326/webrev/

Thanks,
Joe