MoveFirst、MoveLast、MoveNext、MovePrevious メソッドの例 (VJ++)

この例では、与えられたコマンドに基づいて Recordset のレコード ポインタを移動するのに、MoveFirst、MoveLast、MoveNext、および MovePrevious メソッドを使います。このプロシージャを実行するには、MoveAny プロシージャが必要です。

import com.ms.wfc.data.*;
import java.io.*;

public class MoveFirstX  // DLL name.
{
// Main Function

public static void main( String rgArg[] )
{
    MoveFirstX();
    System.exit(0);
}

// MoveFirstX Function

static void MoveFirstX()
{
    // Declarations
    Recordset rsAuthors = null;
    BufferedReader in = 
            new BufferedReader(new InputStreamReader(System.in));
    String  line = null;

    String strCnn = "Provider=sqloledb;data source=dianaped4;"
        + "Initial Catalog=Pubs;User Id=sa;Password=;";

    String strMessage = "UPDATE Titles SET type = 'psychology' "
        +"WHERE type = 'self_help'";

    int intCommand = 0;
    String strFName;
    String strLName;

    try
    {
        // Open recordset from Authors table.
        rsAuthors = new Recordset();
        rsAuthors.setCursorLocation( AdoEnums.CursorLocation.CLIENT );

        // Use client cursor to enable AbsolutePosition property.
        rsAuthors.open( "Authors", strCnn, AdoEnums.CursorType.STATIC,
            AdoEnums.LockType.BATCHOPTIMISTIC, AdoEnums.CommandType.TABLE );

        // Get user's move requests and show current record information.
        while( true )    // Continuous loop.
        {
        // Assign field information to variable to simplify output code.
            strFName = rsAuthors.getField("au_fname").getString();
            strLName = rsAuthors.getField("au_lname").getString();

            System.out.println
                ( "\nName: " + strFName + " " + strLName + "\n"
                + "Record " + rsAuthors.getAbsolutePosition()
                + " of " + rsAuthors.getRecordCount() + "\n\n" );
            System.out.println( "[1 - MoveFirst, 2 - MoveLast, \n");
            System.out.println( " 3 - MoveNext, 4 - MovePrevious]\n");

            // User types a number followed by enter (cr-lf).
            line = in.readLine();

            // No entry exits program loop.
            if (line.length() == 0) break;
            // Convert string entry to int.
            intCommand = Integer.parseInt(line);
            // Out of range entry exits program loop.
            if ((intCommand < 1) || (intCommand > 4)) break;

            // Call method based on user's validated selection.
            MoveAny(intCommand, rsAuthors);
        }
        rsAuthors.close();
    }
    catch( AdoException ae )
    {
        // Notify user of any errors that result from ADO.

        // As passing a Recordset, check for null pointer first.
        if (rsAuthors != null)
        {
            PrintProviderError(rsAuthors.getActiveConnection());
        }
        else
        {
            System.out.println("Exception: " + ae.getMessage());
        }
    }
    // System Read requires this catch.
    catch( java.io.IOException je )
    {
        PrintIOError(je);
    }
}

// MoveAny Function

static void MoveAny(int intChoice, Recordset rsTemp)
{
    // Move per selection from user, checking for BOF and EOF.
    try
    {
        switch(intChoice)
        {
        case 1:   // Equals char of 1.
            rsTemp.moveFirst();
            break;
        case 2:   // Equals char of 2.
            rsTemp.moveLast();
            break;
        case 3:   // Equals char of 3.
            rsTemp.moveNext();
            if(rsTemp.getEOF())
            {
                System.out.println("\nAlready at end of recordset!\n");
                rsTemp.moveLast();
            }
            break;
        case 4:   // Equals char of 4.
            rsTemp.movePrevious();
            if(rsTemp.getBOF())
            {
                System.out.println
                    ("\nAlready at beginning of recordset!\n");
                rsTemp.moveFirst();
            }
            break;
        default:
            break;
        }
    }
    catch( AdoException ae )
    {
        // Notify user of any errors that result from ADO.

        // As passing a Recordset, check for null pointer first.
        if (rsTemp != null)
        {
            PrintProviderError(rsTemp.getActiveConnection());
        }
        else
        {
            System.out.println("Exception: " + ae.getMessage());
        }
    }
}

    // PrintProviderError Function

    static void PrintProviderError( Connection Cnn1 )
    {
        // Print Provider errors from Connection object.
        // ErrItem is an item object in the Connection’s Errors collection.
        com.ms.wfc.data.Error  ErrItem = null;
        long nCount = 0;
        int  i      = 0;

        nCount = Cnn1.getErrors().getCount();

        // If there are any errors in the collection, print them.
        if( nCount > 0);
        {
            // Collection ranges from 0 to nCount - 1
            for (i = 0; i< nCount; i++)
            {
                ErrItem = Cnn1.getErrors().getItem(i);
                System.out.println("\t Error number: " + ErrItem.getNumber()
                    + "\t" + ErrItem.getDescription() );
            }
        }

    }

    // PrintIOError Function

    static void PrintIOError( java.io.IOException je)
    {
        System.out.println("Error \n");
        System.out.println("\tSource = " + je.getClass() + "\n");
        System.out.println("\tDescription = " + je.getMessage() + "\n");
    }
}