Entering a Date value in Postgresql with Java

Question

I am trying to program a database application with java & PostgreSQL. I have some rows with date data type. But i cant add any entries to the database with this code :

Date aDate = null;
aDate.setYear(1990);
aDate.setDate(01);
aDate.setMonth(05);

preparedStatement prep = connection.prepareStatement("insert 
into exampletable values (?,?);");
prep.setDate(1, (java.sql.Date) aDate);
prep.setDate(2, (java.sql.Date) aDate);

How can i add a date in a postgreSQL row with queries in java?

The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API. Check this answer and this answer to learn how to use java.time API with JDBC. — Arvind Kumar Avinash
– Arvind Kumar Avinash, Commented Jun 27, 2021 at 13:34

Jon Skeet · Accepted Answer · 2011-10-05 14:12:20Z

6

It's not clear whether or not this is your only problem, but this code is almost certainly not what you want:

Date aDate = null;
aDate.setYear(1990);
aDate.setDate(01);
aDate.setMonth(05);

It will throw a NullPointerException because you're trying to dereference null
You're then trying to set the year to 3890AD (java.util.Date is 1900-based for years)
You're then setting the month to June. If you thought you were setting the month to May, think again - Date is 0-based for months
All the methods you're using are deprecated - that should raise a big warning light for you
You're then trying to cast aDate to java.sql.Date but there's no sign that it is a java.sql.Date

I would suggest:

Either use Joda Time as a far better date/time API, or java.util.Calendar
Make sure you actually create an instance before you set values
Probably create a new java.sql.Date later on.

For example:

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, 1990);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.set(Calendar.MONTH, 4); // Assuming you wanted May 1st

java.sql.Date date = new java.sql.Date(calendar.getTime().getTime());

// Ideally specify the columns here as well...
PreparedStatement prep = connection.prepareStatement(
    "insert into exampletable values (?,?)");
prep.setDate(1, date);
prep.setDate(2, date);

answered Oct 5, 2011 at 14:12

Jon Skeet

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1 Comment

Jon Skeet Over a year ago

@RafaelWerlang: Your edit suggestion is incorrect. Calendar.getTime() returns a java.util.Date; java.util.Date.getTime() returns a long. There's a java.sql.Date(long) constructor, but no java.sql.Date(java.util.Date) constructor.

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