从文件扫描时出现 InputMismatchError

Question

我正在尝试将 .txt 文件中的数据读入我的程序，但它抛出了 InputMismatchErrors，尽管它看起来不应该。

错误

**********HELLO***********
Which animal are you looking to check into the kennel?: 
Dog
Cat
cat //typed entry
Using file cats.txt
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at KennelDemo.initialise(KennelDemo.java:82)
at KennelDemo.main(KennelDemo.java:337)

// The error occurs on this line:
infile.nextInt(); 
int feedsPerDay = infile.nextInt();

代码片段如下：

public class KennelDemo {
private String filename; // holds the name of the file
private Kennel kennel; // holds the kennel
private Scanner scan; // so we can read from keyboard
private String tempFileName;
private String dogsFile = "dogs.txt";
private String catsFile = "cats.txt";

/*
 * Notice how we can make this private, since we only call from main which
 * is in this class. We don't want this class to be used by any other class.
 */
private KennelDemo() {
    scan = new Scanner(System.in);
    boolean fileCorrect = false;
    do {

        System.out.print("Which animal are you looking to check into the kennel?: " + "\n");
        System.out.println("Dog");
        System.out.println("Cat");  
        tempFileName = scan.next();
        if(tempFileName.toLowerCase().equals("dog") || tempFileName.toLowerCase().equals("cat")) {
           filename = tempFileName.toLowerCase().equals("dog") ? dogsFile : catsFile;
           fileCorrect = true;
        }
        else {
          System.out.println("That is not a valid filename, please enter either 'Dog' or 'cat' in lowercase.");
        }
    }
        while(!fileCorrect);
}

/*
 * initialise() method runs from the main and reads from a file
 */
private void initialise() {
    kennel = new Kennel();

    System.out.println("Using file " + filename);

    // Using try-with-resource (see my slides from session 15)
    try(FileReader fr = new FileReader(filename);
        BufferedReader br = new BufferedReader(fr);
        Scanner infile = new Scanner(br)){

        String kennelName = infile.nextLine();
        int kennelSize = infile.nextInt();
        infile.nextLine();
        kennel.setCapacity(kennelSize);
        int numPets = infile.nextInt();
        infile.nextLine();
        kennel.setName(kennelName);
        for(int i=0; i < numPets; i++){
            String PetName = infile.nextLine();
            int numOwners = infile.nextInt();
            infile.nextLine();
            ArrayList<Owner> owners = new ArrayList<>();
            for(int oCount=0; oCount < numOwners; oCount++){
                String name = infile.nextLine();
                String phone = infile.nextLine();
                Owner owner = new Owner(name, phone);
                owners.add(owner);
            }
            //boolean mutualBoolean = infile.nextBoolean();
            infile.nextLine();
            String favFood = infile.nextLine();
            infile.nextInt(); 
            int feedsPerDay = infile.nextInt();

            Pet Pet = new Pet(PetName, owners, favFood, feedsPerDay);
            kennel.addPet(Pet);
        }

    } catch (FileNotFoundException e) {
        System.err.println("The file: " + " does not exist. Assuming first use and an empty file." +
                           " If this is not the first use then have you accidentally deleted the file?");
    } catch (IOException e) {
        System.err.println("An unexpected error occurred when trying to open the file " + filename);
        System.err.println(e.getMessage());
    }
}

和 .txt 文件 (cats.txt)

DogsRUs
20
1
TestCat
1
TestOwner
12345
TestFood
3

几个小时以来，我一直在努力解决这个问题（布尔值有问题，我最终完全退出了程序，因为这让我很烦）而且我几乎没有做到任何进展。我已经多次重写 .txt 文件以确保每条数据都与接下来读取的内容相对应，但它仍然会引发错误。

提前致谢。

Answer 1

当您在第二个 for 循环中将所有者添加到列表后调用 infile.nextLine(); 时，您将跳过最喜欢的食物行，这意味着对 nextInt 的下一次调用将遇到 String，而不是有效的 int。删除对 nextLine() 的调用，你应该没问题。

//boolean mutualBoolean = infile.nextBoolean();
infile.nextLine();
String favFood = infile.nextLine();
infile.nextInt(); 
int feedsPerDay = infile.nextInt();

变成

//boolean mutualBoolean = infile.nextBoolean();
String favFood = infile.nextLine();
int feedsPerDay = infile.nextInt();

此外，您不需要在阅读喜欢的食物（见上面的代码）后调用infile.nextInt()，因为您已经在正确的线路上了。

最后，您只需声明一个 Scanner 实例如下：

Scanner infile = new Scanner(new File(filename));

而不是

FileReader fr = new FileReader(filename);
BufferedReader br = new BufferedReader(fr);
Scanner infile = new Scanner(br)

从文件扫描时出现 InputMismatchError

InputMismatchError when scanning from file

java

inputmismatchexception