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?

Answer 1

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);