OrderMatters.java

/*   Copyright 2004 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.xmlbeans.samples.cursor;

import statement.StatementDocument;
import statement.StatementDocument.Statement;
import statement.Transaction;
import java.io.File;

import org.apache.xmlbeans.XmlCursor;

import javax.xml.namespace.QName;

public class OrderMatters
{
    private static QName deposit = new QName( "http://statement", "deposit" );

    public static void main ( String[] args ) throws Exception
    {
        // load the xml instance into the store and return a
        // strongly typed instance of StatementDocument
        StatementDocument stmtDoc = StatementDocument.Factory.parse( new File( args[ 0 ] ) );

        System.out.println( "Valid statement instance? " + stmtDoc.validate() );

        float balance = balanceOutOfOrder(stmtDoc);

        System.out.println( "Ending balance: $" + balance );

        balance = balanceInOrder(stmtDoc);

        System.out.println( "Ending balance: $" + balance );
    }

    /**
     * Out of order balance: the ease of stronly-typed XmlObjects!
     */
    public static float balanceOutOfOrder(StatementDocument stmtDoc)
    {
        Statement stmt = stmtDoc.getStatement();

        float balance = 0;

        Transaction[] deposits    = stmt.getDepositArray();
        Transaction[] withdrawals = stmt.getWithdrawalArray();

        for ( int i = 0 ; i < deposits.length ; i++ )
            balance += deposits[ i ].getAmount();

        for ( int i = 0 ; i < withdrawals.length ; i++ )
            balance -= withdrawals[ i ].getAmount();

        return balance;
    }

    /**
     * In order balance: the power of XmlCursor!
     */
    public static float balanceInOrder(StatementDocument stmtDoc)
    {
        float balance = 0;

        XmlCursor cursor = stmtDoc.newCursor();

        // use xpath to select elements
        cursor.selectPath( "*/*" );

        // iterate over the selection
        while ( cursor.toNextSelection() )
        {
            // two views of the same data:
            // move back and forth between XmlObject <-> XmlCursor
            Transaction trans = (Transaction) cursor.getObject();

            float amount = trans.getAmount();

            if (cursor.getName().equals( deposit ))
                balance += amount;
            else if ((balance -= amount) < 0)
            {
                // doh!
                System.out.println( "Negative balance: $" + balance );
                balance -= 50;
            }
        }

        return balance;
    }

}