Java ResultSet.wasNull()

boolean wasNull()  throws SQLException

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
//from   w w  w .ja va2 s  . c  om
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getConnection();
    Statement st = conn.createStatement();

    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (10,'nameValue')");
    st.executeUpdate("insert into survey (id,name ) values (null,null)");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");

    while (rs.next()) {
      int id = rs.getInt(1);
      System.out.println(id);
      if( rs.wasNull( ) ) {
        id = -1;
      }
      System.out.println(id);
    }
    rs.close();
    st.close();
    conn.close();
  }
  private static Connection getConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    String url = "jdbc:hsqldb:mem:data/tutorial";

    return DriverManager.getConnection(url, "sa", "");
  }
}