java - 死代码java eclipse

Question

我正在尝试检查用户给出的单词是否已存在于文本文件中或它的子字符串是否已存在。这是我的代码:

String ans = null;
Scanner scanner = null;
do
{
    System.out.print("Please enter a new word: ");
    String Nword = scan.next();
    System.out.print("And its appropriate Hint: ");
    String Nhint = scan.next();

    Word word = new Word(Nword , Nhint);
    File file = new File("C:\\Users\\Charbel\\Desktop\\Dictionary.txt");
    file.createNewFile();
    scanner = new Scanner(file);
    if (scanner != null)
    {
        String line;
        while (scanner.hasNext()) {
            line = scanner.next();
            for(int i = 0 ; i<line.length(); i++)
                if ((line.equals(Nword)) || (Nword.equals(line.substring(i))))
                {
                    System.out.println("The word already exists.");
                    break;
                }
        }
    }
    else
    {
        FileWriter writer = new FileWriter(file , true);
        writer.write(word.toString());
        writer.write(System.lineSeparator());
        writer.flush();
        writer.close();

        System.out.println("Your word has successfuly added.");
        System.out.print("\nWould you like to add another word ?\nPress 0 to continue.");
        ans = scan.next();
    }
} while(ans.equals("0"));

Eclipse 说 else 条件之后的语句是“死代码”，我不知道为什么。

Answer 1

scanner = new Scanner(file);

scanner 已初始化，永远不能为 null，因此永远不会到达 else 语句。

参见 constructor :

Throws:
FileNotFoundException - if source is not found

因此，如果 file 不存在，scanner 将不会是 null，您将遇到一个异常.