Question

我努力寻找解决方案，或者至少指出我正确的方向......

这是我的ArrayList：books = new ArrayList（）;

我必须搜索包含标题（String）的Book对象。这就是我的......

问题是我只想打印第二个语句，如果找不到。但它似乎是在搜索列表中的每个对象时打印它？

public void searchBookInCollection(String title) 
{
    for (Book book : books)
    {
        if(book.getTitle().equalsIgnoreCase(title)) 
        {
            book.displayBookInformation();
        }
        else
        {
            System.out.println("Nope we don't have it");
        }
    }
 }

Answer 1

将其更改为具有布尔找到的标志

public void searchBookInCollection(String title) 
{
      boolean found = false;
      for (Book book : books)
      {
            if(book.getTitle().equalsIgnoreCase(title)) 
            {
               book.displayBookInformation();
               found = true;
               break;  // no point to keep going? 
            }
       }
       if (!found)
       {
           System.out.println("Nope we don't have it");
       }
}

Answer 2

由于该方法显示searchBookInCollection()，因此应该返回书籍或名称或其他内容。这提供了另一种解决方案，

public String findBook(String title) { // "InCollection" does not help end user, "find" follows standard naming convention
    for (String book : books) {
        if (book.equalsIgnoreCase(title)) {
            return book; // This is debated, if you want "one return" here, use temporary variable.
        }
    }
    throw new NoSuchElementException("Title was not found!"); // Throw gives the end user a chance to handle the exception.
}

搜索ArrayList对象：对象的

2 个答案: