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https://issues.apache.org/jira/browse/LANG-360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12540209
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Henri Yandell commented on LANG-360:
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The problem with the method lies with the automagical creation. Passing in null
should not lead to a StringBuffer being created and then returned - the user
should be responsible for their parameters. StringBuffer methods should have
void return types.
The best way to solve that is to deprecate the old StringBuffer method and add
a new method of:
* public static void identityToString(StringBuffer, Object)
One that throws an NPE if the first param is null.
The second question is what to do in the case of Object being null. Currently
the String variant returns null. The new StringBuffer variant could either
append "null", "", or throw an NPE. The old library was effectively appending
"", so that's the current behaviour. I can see value in all three options, so
suggest we stick with the empty String option - ie) nothing happens to the
buffer.
> Why does appendIdentityToString return null?
> --------------------------------------------
>
> Key: LANG-360
> URL: https://issues.apache.org/jira/browse/LANG-360
> Project: Commons Lang
> Issue Type: Bug
> Reporter: Jörg Gottschling
> Fix For: 2.4
>
> Attachments: LANG-360.patch
>
>
> ObjectUtils is designed to handle null imputs gracefully. But
> ObjectUtils.appendIdentityToString does not. It returns null unnessecary if
> you pass null als second parameter (the object to get the identity from). For
> example appendIdentityToString(new StringBuffer(), null) will return null!
> Which is an uncommen behaviour. Think about code like this:
> ObjectUtils.appendIdentityToString(buffer, param1)
> .appendIdentityToString(buffer, param2)
> .appendIdentityToString(buffer, param3);
> This will cause an NPE if param1 or param2 ist null. There may be other code
> where a NPE will not happen, but the code is used for debugging and there
> will be an unexpected or wrong output.
> So you shoul return the StringBuffer which is passed in or a new one if null.
> The harder question is what to do with the object. I think we should append
> "null" to the StringBuffer, because this is what I would expect and what the
> passed reference is.
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