Java Object Null检查方法 [英] Java Object Null Check for method

问题描述

我需要在该公式中为书籍[i]创建一个空检查，并且我不确定如何进行此检查，因为我对空检查并不十分熟悉，并且在编程时还很陌生.任何帮助都将不胜感激！

I need to create a null check in this formula for the books[i] and I am not entirely sure how to go about this as I am not greatly familiar with null checks and very new at programming. Any and all help is much appreciated!

public static double calculateInventoryTotal(Book[] books)
{
    double total = 0;

    for (int i = 0; i < books.length; i++)
    {
        total += books[i].getPrice();
    }

    return total;
}

推荐答案

首先，您应该检查books本身是否不为null，然后只需检查books[i] != null:

First you should check if books itself isn't null, then simply check whether books[i] != null:

if(books==null) throw new IllegalArgumentException();

for (int i = 0; i < books.length; i++){
   if(books[i] != null){
        total += books[i].getPrice();
   }
}

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