/*
 * @(#)RowSetMetaDataImpl.java	1.13 06/05/28
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.sql.rowset;

import java.sql.*;
import javax.sql.*;
import java.io.*;

import java.lang.reflect.*;

/**
 * Provides implementations for the methods that set and get
 * metadata information about a <code>RowSet</code> object's columns.
 * A <code>RowSetMetaDataImpl</code> object keeps track of the
 * number of columns in the rowset and maintains an internal array
 * of column attributes for each column.
 * <P>
 * A <code>RowSet</code> object creates a <code>RowSetMetaDataImpl</code>
 * object internally in order to set and retrieve information about
 * its columns.
 * <P>
 * NOTE: All metadata in a <code>RowSetMetaDataImpl</code> object 
 * should be considered as unavailable until the <code>RowSet</code> object 
 * that it describes is populated.
 * Therefore, any <code>RowSetMetaDataImpl</code> method that retrieves information 
 * is defined as having unspecified behavior when it is called
 * before the <code>RowSet</code> object contains data.
 */
public class RowSetMetaDataImpl implements RowSetMetaData,  Serializable {

    /**
     * The number of columns in the <code>RowSet</code> object that created
     * this <code>RowSetMetaDataImpl</code> object.
     * @serial
     */
    private int colCount;

    /**
     * An array of <code>ColInfo</code> objects used to store information
     * about each column in the <code>RowSet</code> object for which
     * this <code>RowSetMetaDataImpl</code> object was created. The first
     * <code>ColInfo</code> object in this array contains information about
     * the first column in the <code>RowSet</code> object, the second element
     * contains information about the second column, and so on.
     * @serial
     */
    private ColInfo[] colInfo;

    /**
     * Checks to see that the designated column is a valid column number for
     * the <code>RowSet</code> object for which this <code>RowSetMetaDataImpl</code>
     * was created. To be valid, a column number must be greater than
     * <code>0</code> and less than or equal to the number of columns in a row.
     * @throws <code>SQLException</code> with the message "Invalid column index"
     *        if the given column number is out of the range of valid column
     *        numbers for the <code>RowSet</code> object
     */
    private void checkColRange(int col) throws SQLException {
        if (col <= 0 || col > colCount) {
            throw new SQLException("Invalid column index :"+col);
        }
    }
    
    /**
     * Checks to see that the given SQL type is a valid column type and throws an
     * <code>SQLException</code> object if it is not.
     * To be valid, a SQL type must be one of the constant values
     * in the <code><a href="../../sql/Types.html">java.sql.Types</a></code> 
     * class.     
     *
     * @param SQLType an <code>int</code> defined in the class <code>java.sql.Types</code>
     * @throws SQLException if the given <code>int</code> is not a constant defined in the 
     *         class <code>java.sql.Types</code>
     */
    private void checkColType(int SQLType) throws SQLException {
        try {
            Class c = java.sql.Types.class;
            Field[] publicFields = c.getFields();        
            int fieldValue = 0;
            for (int i = 0; i < publicFields.length; i++) {              
                fieldValue = publicFields[i].getInt(c);                
                if (fieldValue == SQLType) {                    
                    return;                    
                 }
            }
        } catch (Exception e) {
            throw new SQLException(e.getMessage());
        }
        throw new SQLException("Invalid SQL type for column");
    }    

    /**
     * Sets to the given number the number of columns in the <code>RowSet</code> 
     * object for which this <code>RowSetMetaDataImpl</code> object was created.
     *