Re: str.equals(null) or str==null ?

From:
Hendrik Maryns <hendrik_maryns@despammed.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 01 Aug 2006 09:28:53 +0200
Message-ID:
<eamvrl$km5$1@newsserv.zdv.uni-tuebingen.de>
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Ingo R. Homann schreef:

Hi,

David Segall wrote:

Is there a difference between the two tests on the object str:

if (str == null) {...
and
if (str.equals(null)) {...


Of course: If str is null, the first one will exeute the if-block while
the latter one will throw a NullPointerException.

Or am I missing something?


Yes, from String.java:

public boolean equals (Object object) {
    if (object == this) return true;
    if (object instanceof String) {
        String s = (String)object;
        if (count != s.count ||
            (hashCode != s.hashCode && hashCode != 0 && s.hashCode != 0))
                return false;
        return regionMatches(0, s, 0, count);
    }
    return false;
}

This will return false if object is null.

H.
- --
Hendrik Maryns

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