.nextval JDBC insert problem

I try to insert into table with sequence .nextval as primary key, the sql in Java is

sql = "INSERT INTO USER 
         (USER_PK, ACCOUNTNUMBER, FIRSTNAME, LASTNAME, EMAIL ) 
       VALUES 
         (?,?,?,?,?)";
   ps = conn.prepareStatement(sql);
   ps.setString(1, "User.nextval");
   ps.setStri开发者_StackOverflow社区ng(2, accountNumber);
   ps.setString(3, firstName);
   ps.setString(4, lastName);
   ps.setString(5, email);

However, the error is ORA-01722: invalid number

All the other fields are correct, I think it is the problem of sequence, is this correct?

The problem is that the first column is a numeric data type, but your prepared statement is submitting a string/VARCHAR data type. The statement is run as-is, there's no opportunity for Oracle to convert your use of nextval to get the sequence value.

Here's an alternative via Java's PreparedStatement syntax:

sql = "INSERT INTO USER 
        (USER_PK, ACCOUNTNUMBER, FIRSTNAME, LASTNAME, EMAIL ) 
       VALUES 
        (user.nextval, ?, ?, ?, ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, accountNumber);
ps.setString(2, firstName);
ps.setString(3, lastName);
ps.setString(4, email);

This assumes that user is an existing sequence -- change to suit.