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From "Daniel Trebbien (Created) (JIRA)" <>
Subject [jira] [Created] (LANG-786) StringUtils equals() relies on undefined behavior
Date Fri, 20 Jan 2012 19:52:40 GMT
StringUtils equals() relies on undefined behavior

                 Key: LANG-786
             Project: Commons Lang
          Issue Type: Bug
          Components: lang.*
    Affects Versions: 3.0
         Environment: java version "1.7.0_02"
Java(TM) SE Runtime Environment (build 1.7.0_02-b13)
Java HotSpot(TM) 64-Bit Server VM (build 22.0-b10, mixed mode)

Fedora 15 AMD64
            Reporter: Daniel Trebbien

Since the {{java.lang.CharSequence}} class was first introduced in 1.4, the JavaDoc block
has contained the following note:

This interface does not refine the general contracts of the equals and hashCode methods. The
result of comparing two objects that implement CharSequence is therefore, in general, undefined.
Each object may be implemented by a different class, and there is no guarantee that each class
will be capable of testing its instances for equality with those of the other.

When the signature of the StringUtils equals() method was changed from {{equals(String, String)}}
to {{equals(CharSequence, CharSequence)}} in R920543, the implementation still relied on calling
CharSequence#equals(Object) even though, in general, the result is undefined.

One example where {{equals(Object)}} returns {{false}} even though, as CharSequences, two
objects represent equal sequences is when one object is an instance of {{javax.lang.model.element.Name}}
and the other object is a String.

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