Java.lang.NullPointerException when doing SQL on ms access

Question

I am trying to perform Insert and delete commands on an access database and I continue to get a java.lang.NullPointerException when performing the action. Everything is fine when i do a Select * FROM..., I am able to read all of the information I ask for, but when performing the Insert/Delete commands I get the error. Any help would be appreciated, I will copy and past a portion of my code below. All of the fields and variable types match with what is in the database.
public void executeAddSecretary() throws SQLException{
String a,b;
a= txtSecLname.getText();
b= txtSecFname.getText();
statement.execute("INSERT INTO Contact_Sec (Sec_Lname,Sec_Fname) Values ('" + a + "', '" + b + "')");
System.out.println("updated Secretary");
public void executeDeleteContact() throws SQLException{
String a = "a";
statement.execute("DELETE FROM Contact WHERE Lname = ('" + a + "')");
System.out.println("deleted contact");
Thanks to anyone who can help me out.

Answer 1

1) Use prepared statement instead of statement.
2) Do like this ...
PreparedStatement prepStmt = null;
try
     String query="INSERT INTO Contact_Sec (Sec_Lname,Sec_Fname) Values (?,?)");
     prepStmt = connection.prepareStatement(query);
     prepStmt.setString(1, value1);
     prepStmt.setString(2, value2);
     prepStmt.executeUpdate();
catch (SQLException e)
     throw e;
catch (Exception e)
     throw e;
finally
     try
          if (prepStmt != null)
               prepStmt.close();
     } catch (Exception e) {}
     try
          if (connection != null)
               connection.close();
     } catch (Exception e) {}
}3) If you still get the null exception then put step wise System.out's
and debug it.
-Rohit