The Java SqlResultSet Class

 
    public  class SqlResultSet implements Iterable<SqlTuple>, java.io.Closeable
    {
        /**
        * Get names of result columns
        */
        public String[] getColumnNames() 
        {
            if (columnNames == null) 
            {
                columnNames = getColumnNames(id);
            }
            return columnNames;
        }
 
        private static final Class sql2javaTypeMap[] = 
        {
            Object.class,  // tpNull,
            Boolean.class, // tpBool,
            Long.class,    // tpInt1,
            Long.class,    // tpUInt1,
            Long.class,    // tpInt2,
            Long.class,    // tpUInt2,
            Long.class,    // tpInt4,
            Long.class,    // tpUInt4,
            Long.class,    // tpInt8,
            Long.class,    // tpUInt8,
            Double.class,  // tpReal4,
            Double.class,  // tpReal8,
            Date.class,    // tpDateTime,
            java.math.BigDecimal.class, // tpNumeric,
            String.class,  // tpUnicode,
            String.class,  // tpString,
            byte[].class,  // tpRaw,
            Long.class,    // tpReference,
            null,  // tpArray,
            null,  // tpStruct,
            byte[].class,  // tpBlob,
            null,  // tpDataSource,
            null,  // tpList,
            SequenceIterator.class, // tpSequence
            byte[].class, // RSQL + tpSequence = tpArray + element type tpInt1
            byte[].class, // RSQL + tpSequence = tpArray + element type tpUInt1
            short[].class, // RSQL + tpSequence = tpArray + element type tpInt2
            char[].class, // RSQL + tpSequence = tpArray + element type tpUInt2
            int[].class, // RSQL + tpSequence = tpArray + element type tpInt4
            int[].class, // RSQL + tpSequence = tpArray + element type tpUInt4
            long[].class, // RSQL + tpSequence = tpArray + element type tpInt8
            long[].class, // RSQL + tpSequence = tpArray + element type tpUInt8
            float[].class, // RSQL + tpSequence = tpArray + element type tpReal4
            double[].class, // RSQL + tpSequence = tpArray + element type tpReal8
            String[].class, // RSQL + tpSequence = tpArray + element type tpString
            Date[].class    // RSQL + tpSequence = tpArray + element type tpDateTime
        };
 
        /**
        * Get types of result columns
        */
        public Class[] getColumnTypes() 
        {
            if (columnTypes == null) 
            {
                int[] sqlTypes = getColumnTypes(id);
                columnTypes = new Class[sqlTypes.length];
                for (int i = 0; i < sqlTypes.length; i++) 
                {
                    columnTypes[i] = sql2javaTypeMap[sqlTypes[i]];
                }
            }
            return columnTypes;
        }
 
        /**
        * Get number of result columns
        */
        public int getNumberOfColumns() 
        {
            return getNumberOfColumns(id);
        }
 
        /**
        * Find column index by name
        * @param column name of the result column
        * @return 0-based index of this column in result set
        */
        public int getColumnNo(String column) 
        {
            String[] columns = getColumnNames();
            for (int i = 0 ; i < columns.length; i++) 
            {
                if (column.equals(columns[i])) 
                {
                    return i;
                }
            }
            throw new IllegalArgumentException("No such column " + column);
        }
 
        /**
        * Close the cursor.
        */
        public void close() 
        {
            if (id != 0) 
            {
                Set<SqlCursor> attachedCursors = cursors;
                cursors = null;
                for (SqlCursor cursor : attachedCursors) 
                {
                    cursor.close();
                }
                con.detachResultSet(this);
                close(id);
                id = 0;
            }
        }
 
        protected void finalize() 
        {
            close();
        }
 
        /**
        * Get the iterator.
        */
        public Iterator<SqlTuple> iterator() 
        {
            SqlCursor cursor = new SqlCursor(this, getIterator(id));
            cursors.add(cursor);
            return cursor;
        }
 
        void detachCursor(SqlCursor cursor) 
        {
            if (cursors != null) 
            {
                cursors.remove(cursor);
            }
        }
 
        SqlResultSet(SqlConnection c, long ds) 
        {
            con = c;
            id = ds;
            cursors = new HashSet<SqlCursor>();
        }
 
        private long id;
        private SqlConnection con;
        Set<SqlCursor> cursors;
        private String[] columnNames;
        private Class[] columnTypes;
        private native long getIterator(long id);
        private native String[] getColumnNames(long id);
        private native int[] getColumnTypes(long id);
        private native int getNumberOfColumns(long id);
        private native void close(long id);
    };