New to Java

I am facing what I think is a fairly common problem for which there might be a standard solution.
I use an inner class to represent a row in a database table.
The column names are represented with an enumeration.
The column values, themselves, are stored as instance values.
I perceive the problem to be that I need someway to associate each item in the enum in Row with an instance variable in Row .

public final class TblDictionary {
  Set<Row> dbTbl = new HashSet<Row>();

  // ......
  public int loadIntoDb(Connection conn) throws Exception {
    StringBuilder sql = new StringBuilder();
    sql.append("INSERT INTO dictionary(");
    for(Row.ColName c : Row.ColName.values()) sql.append(" " + c + ",");
    sql.deleteCharAt(sql.length() - 1);
    sql.append(") VALUES(");
    for(Row.ColName c : Row.ColName.values()) sql.append(" ?,");
    sql.deleteCharAt(sql.length() - 1);
    sql.append(")");
    PreparedStatement prpStmt = conn.prepareStatement(sql.toString());
    for(Row r : dbTbl) {
      for(Row.ColName c : Row.ColName.values()) prpStmtInsert(prpStmt, r, c);
      prpStmt.executeUpdate();
    }
  }

  static void prpStmtInsert(PreparedStatement ps, Row r, Row.ColName c) throws Exception {
    Object obj = r.getObj(c);
    if(String.class.isInstance(obj))  { ps.setString(c.ordinal() + 1, obj.toString()); return; }
    if(Integer.class.isInstance(obj)) { ps.setInt(c.ordinal() + 1, ((Integer) obj).intValue()); return; }
  }

        static class Row {
          public enum ColName {
            WORD, DEF, PAGENMB
          }
          final public int pagenmb;
          final public String word, def;
          Row(String word, String def, int pagenmb) {
            this.word = word; this.def = def; this.pagenmb = pagenmb;
          }

          private Object getObj(ColName col) {
            if(col == ColName.WORD)     return word;
            if(col == ColName.DEF)      return def;
            if(col == ColName.PAGENMB)  return Integer.valueOf(pagenmb);
            return null;
          }
        }
}

Because the classes represented by the enum are not all of the same type, I can only cast out of "getObj(ColName col);" to Object. Then, I must rely on "*.class.isInstance(x)" or reflection to deal with the returned object.

" loadIntoDb(Connection conn)" is a flexible method. I cut/paste it into all my classes and needs almost no changes to make it work. But I have that problem of how to extract the value of a column from an instance of Row by specifying the column name using the ColName enumeration.

Edited by: triym on Aug 8, 2011 5:43 PM