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From: =?UTF-8?Q?Arne_Vajh=c3=b8j?= <arne@vajhoej.dk>
Newsgroups: comp.lang.java.programmer
Subject: Re: Testing the functionality of sub classes
Date: Sun, 20 Aug 2017 11:17:35 -0400
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On 8/20/2017 10:35 AM, Cecil Westerhof wrote:
> Arne Vajhøj <arne@vajhoej.dk> writes:
> 
>> On 8/20/2017 9:36 AM, Cecil Westerhof wrote:
>>> Cecil Westerhof <Cecil@decebal.nl> writes:
>>>> Just to satisfy my curiosity I executed (I do not like the formatting,
>>>> but that is what Eclipse does):
>>>>       try (
>>>>               Statement stmt = conn.createStatement();
>>>>               ResultSet rsOne = stmt.executeQuery("SELECT 12 AS twelve");
>>>>               ResultSet rsTwo = stmt.executeQuery("SELECT 'Hello World!' AS message")
>>>>               ) {
>>>>           System.out.println(stmt);
>>>>           System.out.println(rsOne);
>>>>           System.out.println(rsTwo);
>>>>       }
>>>>
>>>> And this gives:
>>>>       org.sqlite.jdbc4.JDBC4Statement@685f4c2e
>>>>       org.sqlite.jdbc4.JDBC4ResultSet@7daf6ecc
>>>>       org.sqlite.jdbc4.JDBC4ResultSet@7daf6ecc
>>>>
>>>> So yes, it is like you said: the ResultSet is reused. Is also more
>>>> logical. I jumped to a conclusion.
>>>
>>> With a H2 database I get:
>>>       stat0
>>>       rs0: null
>>>       rs1: org.h2.result.LocalResult@1bc6a36e columns: 1 rows: 1 pos: -1
>>
>> That is what happens when you try and do unsupported things: you get
>> undefined/implementation specific behavior. Bad!
> 
> Nope, it shows that the H2 driver does follow the standards (and the
> SQLite3 driver does not). The first ResultSet is closed as it should
> be. You can do an isClosed on it. So it is not null, but displays a
> null to show you should not use it anymore.

The contract for toString is extremely vague.

I do not see any indication than SQLite does not follow
JDBC standard.

Reusing result set object should be perfectly valid
per JDBC standard.

And toString can practically return anything.

Arne