[英]Is my logic to determine the most sold product correct?
我想確定實例庫存向量中最暢銷的產品。
public void mostSold(Vector <Stock> temp){
System.out.println ("Generating Data... Please Wait!");
delay(650);
System.out.println ("-------Most Sold Product(s)-------");
for(int i = 0; i < temp.size(); i ++){
s = temp.elementAt(i); // Stock s = new Stock();
sold1 = s.getSold();
sold2 = msold.getSold(); //Stock msold = new Stock();
if(sold1 > sold2)
msold = s;
else if (sold2 > sold1)
msold = msold;
else if (sold1 == sold2){
equal = true;
}
}
if(!equal)
System.out.println (msold.toSold());
else{
System.out.println (msold.toSold());
System.out.println (s.toSold());
}
System.out.println ();
}
剛開始執行時,它工作正常,但是如果我一次執行兩次,控制台將同時輸出mostSold和MinimumSold ...!
輸出! 第一次運行:(效果不錯)
Generating Data... Please Wait!
-------Most Sold Product(s)-------
Product Name: iphone
Product ID: 0123P
Quantity Sold: 10
Generating Data... Please Wait!
-------Least Sold Product(s)-------
Product Name: nexus
Product ID: 2345P
Quantity Sold: 1
第二次運行:
Generating Data... Please Wait!
-------Most Sold Product(s)-------
Product Name: iphone
Product ID: 0123P
Quantity Sold: 10
Product Name: htc one //WHY IS THIS DISPLAYED!!
Product ID: 3456P
Quantity Sold: 1
Generating Data... Please Wait!
-------Least Sold Product(s)-------
Product Name: nexus
Product ID: 2345P
Quantity Sold: 1
您可能有兩只同等價值的股票。
假設您的股票有1,1,2
因此,您擁有默認值為0的默認庫存,並與while循環中的1(第一批庫存)進行比較:
sold1 > sold2 satisfies and with this default becomes 1st stock with value 1
for循環尋找下一個價值又為1的股票
sold1 == sold2 satisfies and equal becomes true
for循環尋找下一個價值2的下一個股票
sold2 > sold1 satisfies msold remains unchanged
現在看到equal是正確的,因此您輸入else部分並用如下語句將其打印兩次:
System.out.println (msold.toSold());
System.out.println (s.toSold());
您可能只打印最大值,而不是打印舊值。
我建議使用以下簡單的代碼,該代碼可在兩個階段中工作:
sold
的最大值。 這是代碼:
public List<Stock> getMostSold(Iterable<Stock> stocks) {
int maxSold = Integer.MIN_VALUE;
for (Stock stock : stocks) {
maxSold = Math.max(maxSold, stock.getSold());
}
List<Stock> result = new ArrayList<>();
for (Stock stock : stocks) {
if (stock.getSold() == maxSold) {
result.add(stock);
}
}
return result;
}
重要的是,此方法沒有副作用,也就是說,它不會修改類的任何字段或其他內容。 因此,您可以根據需要多次調用它,並且始終可以得到相同的結果。
您可以使用Comparator
:
private static final Comparator<Stock> COMPARATOR
= new Comparator<Stock>()
{
@Override
public int compare(final Stock o1, final Stock o2)
{
return Integer.compare(o1.getSold(), o2.getSold());
}
};
// and then (NOTE: assumes at least one element, and no null elements)
public Stock mostSold(final List<Stock> list)
{
final int size = list.size();
Stock ret = list.get(0);
for (int i = 1; i < size; i++)
if (COMPARATOR.compare(list.get(i), ret) > 0)
ret = list.get(i);
return ret;
}
如果您使用Java 8,這會更加容易:
public Stock mostSold(final List<Stock> list)
{
return list.stream().max(COMPARATOR).get();
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.