Java ResultSet copy to generic object or list

java, jdbc, resultset

Solution

This is pretty generic:

Statement st = con.createStatement();
ResultSet rs = st.executeQuery("SELECT * FROM Clients WHERE ID <= 2");

// collect column names
List<String> columnNames = new ArrayList<>();
ResultSetMetaData rsmd = rs.getMetaData();
for (int i = 1; i <= rsmd.getColumnCount(); i++) {
    columnNames.add(rsmd.getColumnLabel(i));
}

int rowIndex = 0;
while (rs.next()) {
    rowIndex++;
    // collect row data as objects in a List
    List<Object> rowData = new ArrayList<>();
    for (int i = 1; i <= rsmd.getColumnCount(); i++) {
        rowData.add(rs.getObject(i));
    }
    // for test purposes, dump contents to check our results
    // (the real code would pass the "rowData" List to some other routine)
    System.out.printf("Row %d%n", rowIndex);
    for (int colIndex = 0; colIndex < rsmd.getColumnCount(); colIndex++) {
        String objType = "null";
        String objString = "";
        Object columnObject = rowData.get(colIndex);
        if (columnObject != null) {
            objString = columnObject.toString() + " ";
            objType = columnObject.getClass().getName();
        }
        System.out.printf("  %s: %s(%s)%n",
                columnNames.get(colIndex), objString, objType);
    }
}

For my test data (in SQL Server) it prints the following to the console:

Row 1
  ID: 1 (java.lang.Integer)
  LastName: Thompson (java.lang.String)
  FirstName: Gord (java.lang.String)
  DOB: (null)
Row 2
  ID: 2 (java.lang.Integer)
  LastName: Loblaw (java.lang.String)
  FirstName: Bob (java.lang.String)
  DOB: 1966-09-12 16:03:00.0 (java.sql.Timestamp)

Problem

I'm aware of the issues with using ResultSet and have seen examples about extracting data into an object (or list), however, I'm wanting to do this in a generic manner i.e. without having to be aware of the class. Is there a way to do this such that the result would be an Object or List that I could then iterate using Reflection? The solutions I've examined that either don't seem to work or require class awareness of the target class include: - How to copy resultset into object? - Copying Java ResultSet I've also tried ResultSetMapper (http://resultsetmapper.sourceforge.net/) and it seems to require the class as well. I really just want an Object or List that I can act on.

Original source

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