List list = new ArrayList();

list.add(new classA("Banana",20));
list.add(new classA("Apple",50));
list.add(new classA("Orange",100));

Collections.sort(list, new SortA());

for(Object o:list){
System.out.print( ((classA)o).toString() + " ");
}

list.clear();
list.add(new classA("Banana",200));
list.add(new classA("Apple",50));
list.add(new classA("Orange",10));

Collections.sort(list, new SortA());

for(Object o:list){
System.out.print( ((classA)o).toString() + " ");
}
}

って感じのを作ったが、値段に応じて商品の並び順が変わったけど？