/*
* ========================================================================
*
* Copyright 2005 Tim O'Brien.
*
* 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 com.discursive.jccook.collections.bag;
import java.text.NumberFormat;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import org.apache.commons.collections.Bag;
import org.apache.commons.collections.bag.HashBag;
import org.apache.commons.lang.StringUtils;
public class BagExample {
Bag inventoryBag = new HashBag();
Album album1 = new Album( "Radiohead", "OK Computer" );
Album album2 = new Album( "Kraftwerk", "The Man-Machine" );
Album album3 = new Album( "Charlie Parker", "Now's the Time" );
Album album4 = new Album( "ABBA", "ABBA - Gold: Greatest Hits" );
public static void main(String[] args) {
BagExample example = new BagExample();
example.start();
}
private void start() {
// Read our inventory into a Bag
populateInventory();
System.out.println( "Inventory before Transactions" );
printAlbums( inventoryBag );
printSeparator();
// A Customer wants to purchase 400 copies of ABBA and 2 copies of Radiohead
Bag shoppingCart1 = new HashBag();
shoppingCart1.add( album4, 500 );
shoppingCart1.add( album3, 150 );
shoppingCart1.add( album1, 2 );
checkout( shoppingCart1, "Customer 1" );
// Another Customer wants to purchase 600 copies of ABBA
Bag shoppingCart2 = new HashBag();
shoppingCart2.add( album4, 600 );
checkout( shoppingCart2, "Customer 2" );
// Another Customer wants to purchase 3 copies of Kraftwerk
Bag shoppingCart3 = new HashBag();
shoppingCart3.add( album2, 3 );
checkout( shoppingCart3, "Customer 3" );
System.out.println( "Inventory after Transactions" );
printAlbums( inventoryBag );
}
private void populateInventory() {
inventoryBag.add( album1, 200 );
inventoryBag.add( album2, 100 );
inventoryBag.add( album3, 500 );
inventoryBag.add( album4, 900 );
}
private void printAlbums( Bag albumBag ) {
Set albums = albumBag.uniqueSet();
Iterator albumIterator = albums.iterator();
while( albumIterator.hasNext() ) {
Album album = (Album) albumIterator.next();
NumberFormat format = NumberFormat.getInstance();
format.setMinimumIntegerDigits( 3 );
format.setMaximumFractionDigits( 0 );
System.out.println( "\t" +
format.format( albumBag.getCount( album ) ) + " - " + album.getBand() );
}
}
private void checkout( Bag shoppingCart, String customer ) {
// Check to see if we have the inventory to cover this purchase
if( inventoryBag.containsAll( (Collection) shoppingCart ) ) {
// Remove these items from our inventory
inventoryBag.removeAll( (Collection) shoppingCart );
System.out.println( customer + " purchased the following items:" );
printAlbums( shoppingCart );
} else {
System.out.println( customer + ", I'm sorry but we are unable to fill your order." );
}
printSeparator();
}
private void printSeparator() {
System.out.println( StringUtils.repeat( "*", 65 ) );
}
}
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