java - 如果 String .contains 方法不适合，如何返回 null？

Question

我有这段代码，如果没有标题包含 wordInTitle 的书，或者 wordInTitle 为 null 或“”，则希望返回 null。我可以设法对 null 和“”执行此操作，但如果没有包含 wordInTitle 的书，则不行。有人可以帮我吗？

public String[] getBookTitlesContaining(String wordInTitle)
{
    int nBooks = 0;
    String[] bookTitle = new String[nBooks];

    for (Book booksTitles : inventory)
    {
        if(booksTitles.getTitle().toLowerCase().contains(wordInTitle.toLowerCase()))
        {
            nBooks++;
        }
    }

    int titleB = 0;
    bookTitle = new String[nBooks];

    for (Book booksTitles : inventory)
    {
        if(booksTitles.getTitle().toLowerCase().contains(wordInTitle.toLowerCase()))
        {
            bookTitle [titleB] = booksTitles.getTitle();
            titleB++;
        }
    }

    if ((wordInTitle == null) || (wordInTitle == "")) 
    {
        return null;
    }

    return bookTitle;

提前致谢

Answer 1

更改此if以包括没有匹配书籍的情况:

if ((wordInTitle == null) || (wordInTitle == "") || (nBooks == 0)) 
{
    return null;
}