NullPointerException on calling ResultSet.getDate()

Question

I am getting a java.lang.NullPointerException on calling ResultSet.getDate() in the following code. The entry in the database, however, doesn't seem to be null. The connection seems to be active, since other fields are being fetched. What am I doing wrong?

try {
    ... /* Code that creates a connection and initializes statement */

    String query = "SELECT * FROM groups WHERE id = 'testGroup1'";
    ResultSet rs = statement.executeQuery(query);
    if(rs.next()) {
        admin = rs.getString("admin_id");
        User.process(admin);
        java.sql.Date created_on = rs.getDate("created_on");
        System.out.println("Created on = " + created_on.toString());
    }
}
catch(Exception e) {
    System.out.println("Stuck here");
    e.printStackTrace();
}

Here's the output and the stack trace:

Admin id = 42          // User.process prints the admin id
Stuck here
java.lang.NullPointerException
    at com.mysql.jdbc.ResultSet.findColumn(ResultSet.java:966)
    at com.mysql.jdbc.ResultSet.getDate(ResultSet.java:1988)
    at com.myapp.server.model.Group.initInfo(Group.java:39)
    ...

I have the following schema:

+-------------------+--------------+------+-----+---------+-------+
| Field             | Type         | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+---------+-------+
| id                | varchar(50)  | NO   | PRI | NULL    |       |
| admin_id          | varchar(50)  | NO   | MUL | NULL    |       |
| created_on        | datetime     | NO   |     | NULL    |       |
+-------------------+--------------+------+-----+---------+-------+

And the following entry in the database:

+------------+----------+---------------------+
| id         | admin_id | created_on          |
+------------+----------+---------------------+
| testGroup1 | 42       | 2014-12-15 22:46:31 |
+------------+----------+---------------------+

I think the issue will be with the SQL date format. Is the `datetime` a proper datatype you are referring? Try `Date` instead. — Aditya Peshave, Dec 15 '14 at 17:31
@SemihEker `getTimestamp()` also throws `NullPointerException`. — John Bupit, Dec 15 '14 at 17:34
It seems like a bug in your jdbc driver. What is the version you are using? Recent mysql drivers do not even have a class called `ResultSet` — Dima, Dec 15 '14 at 17:37
@Dima I was using `mysql-connector-java-5.0.8`. I've upgraded to `mysql-connector-java-5.1.34` which does seem to have a `ResultSet` class. It now shows a `java.sql.SQLException` saying `Operation not allowed after ResultSet closed`. — John Bupit, Dec 15 '14 at 17:47
Thanks for your help. I found `User.process` further queried the database thereby closing the current `ResultSet`. — John Bupit, Dec 15 '14 at 18:03
Like @SemihEker suggested, `getTimestamp()` eventually gives me the desired result. — John Bupit, Dec 15 '14 at 18:11

score 4 · Accepted Answer · edited May 23 '17 at 11:50

4

As mentioned in this question,could you try sthg like that;

I take the code also from the question I mentioned above.

Timestamp timestamp = resultSet.getTimestamp(i);
if (timestamp != null)
    date = new java.util.Date(timestamp.getTime()));

edited May 23 '17 at 11:50

Community

1
1

answered Dec 15 '14 at 17:48

Semih Eker

2,389
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`getTimestamp()` also gives the same error, like I mentioned in the comment. Getting a `NullPointerException` on `rs.getTimestamp("created_on")`. – John Bupit Dec 15 '14 at 17:54
You said that "Like @SemihEker suggested, getTimestamp() eventually gives me the desired result. ". Is this answer ok for you? – Semih Eker Dec 15 '14 at 18:13
Yes, once I get rid of the NPE. [The error](http://stackoverflow.com/a/27490261/1492578) was in the `User.process` function. Thanks. – John Bupit Dec 15 '14 at 18:14

score 3 · Answer 2 · edited May 23 '17 at 11:50

3

The Type of the field created_onin your database is datetime, this is not the same as the Java Date

You'll need to convert it.

If you look at the first answer at this question you'll see how to fix it

edited May 23 '17 at 11:50

Community

1
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answered Dec 15 '14 at 17:34

Liam de Haas

1,258
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Thanks for the link. Using `getTimestamp()` gives me the desired result, once I get rid of the `NullPointerException`. – John Bupit Dec 15 '14 at 18:08
The conversion from a `datetime` (equivalent to a timestamp) is automatic and required by the JDBC specification (it will simply drop the time) – Mark Rotteveel Dec 16 '14 at 13:11

John Bupit · Answer 3 · 2014-12-15T18:19:22.853

I found User.process further queried the database thereby closing the current ResultSet (or so I speculate). The NullPointerException goes away when I do the following:

try {
    ...
    if(rs.next()) {
        admin = rs.getString("admin_id");
        java.sql.Timestamp created_on = rs.getTimestamp("created_on");
        User.process(admin);
    }
}
catch(Exception e) {
    ...
}

Also using getTimestamp() as suggested by other solutions gets me the desired result.

NullPointerException on calling ResultSet.getDate()

3 Answers3