使用 Scanner 解析来自文件的输入。 JAVA

Question

我是 Java 新手，我正在创建一个文件目录来存储电影和有关电影的信息。电影和信息存储在这样的文件中：

Movie Title 
Rating Year Reviews Month Day Year

第一行的标题和第二行的其他信息。因此，对于多部电影，它看起来像这样：

Movie Title
Rating Year Reviews Month Day Year
Movie Title
Rating Year Reviews Month Day Year
Movie Title
Rating Year Reviews Month Day Year

...等等。我有一种将电影打印到控制台的方法，但我遇到了正确格式化电影的问题。电影信息的格式应该是这样的：

   Star Wars     PG    1977   5 stars  1/5/2018

每一列都应正确对齐。标题、评级和年份应保持对齐；的数量 星星和日期右对齐。

第一次它完全按照我想要的方式打印电影信息，但是当我添加多部电影时它会搞砸。这是我的代码，我认为问题出在我尝试格式化输出的 listMovies 方法中，但我包含了所有代码，以防其他地方出现问题。

public class Directory 
{
   private static final String dir = "data/cs2410-directory.data";
   String mTitle,mRat,mRel,mRev,mM,mD,mY;

public Directory()
{
    mTitle = "Movie Title";
    mRat = "Rating";
    mRel = "Year";
    mRev = "Reviews";
    mM = "Month";
    mD = "Day";
    mY ="Year";
    insertMovie();
    listMovies();
}


private void insertMovie()
{
    PrintWriter dirIn = null;

    try
    {
        dirIn = new PrintWriter(new FileOutputStream(dir,true));
    }
    catch (FileNotFoundException e)
    {
        e.printStackTrace();
    }
    dirIn.println(mTitle);
    dirIn.println(mRat+" "+mRel+" "+mRev+" "+mM+" "+mD+" "+mY);
    dirIn.close();
    System.out.print("The following movie has been added to the directory:\n");
    System.out.print(mTitle+" ("+mRel+") "+mRat+"\n");
    System.out.print("Stars: "+mRev+"\n");
    System.out.print("Last Watched: "+mM+"/"+mD+"/"+mY+"\n");
}

private void listMovies()
{
    Scanner dirOut = null;

    try
    {
        dirOut = new Scanner(new FileReader(dir));
    }
    catch (FileNotFoundException e)
    {
        e.printStackTrace();
    }
    while (dirOut.hasNext()) //PROBLEM
    {
        System.out.printf("%-15s%-10s%-10s%5s%10s/%s/%s\n", dirOut.nextLine(),dirOut.next()
                ,dirOut.next(),dirOut.next(),dirOut.next(),dirOut.next(),dirOut.next());
    }
    dirOut.close();
}

public static void main(String[] args)
{
    new Directory();
}

这是一部电影（运行一次程序）之后的输出，它应该是这样的：

The following movie has been added to the directory:
Movie Title (Year) Rating
Stars: Reviews
Last Watched: Month/Day/Year
Movie Title    Rating    Year      Reviews     Month/Day/Year

这是运行两次后：

The following movie has been added to the directory:
Movie Title (Year) Rating
Stars: Reviews
Last Watched: Month/Day/Year
Movie Title    Rating    Year      Reviews     Month/Day/Year
               Movie     Exception in thread "main" java.util.NoSuchElementException
Title     Rating      Year/Reviews/Month
    at java.base/java.util.Scanner.throwFor(Scanner.java:858)
    at java.base/java.util.Scanner.next(Scanner.java:1381)
    at cs2410.assn3.directory.Directory.listMovies(Directory.java:71)
    at cs2410.assn3.directory.Directory.<init>(Directory.java:32)
    at cs2410.assn3.directory.Directory.main(Directory.java:79)

这是运行5次后：

The following movie has been added to the directory:
Movie Title (Year) Rating
Stars: Reviews
Last Watched: Month/Day/Year
Movie Title    Rating    Year      Reviews     Month/Day/Year
               Movie     Title     Rating      Year/Reviews/Month
 Day Year      Movie     Title     Rating      Year/Reviews/Month
 Day Year      Movie     Title     Rating      Year/Reviews/Month
 Day Year      Movie     Title     Rating      Year/Reviews/Month
 Exception in thread "main" java.util.NoSuchElementException
    at java.base/java.util.Scanner.throwFor(Scanner.java:858)
    at java.base/java.util.Scanner.next(Scanner.java:1381)
    at cs2410.assn3.directory.Directory.listMovies(Directory.java:71)
    at cs2410.assn3.directory.Directory.<init>(Directory.java:32)
    at cs2410.assn3.directory.Directory.main(Directory.java:79)

Answer 1

如果我正确理解了这个问题，解决方案很简单： 在 dirOut.hasNext() 循环中的 System.out.printf() 下方添加以下行。

dirOut.nextLine();

您的输入模式有两行；这个额外的 nextLine() 正确地在文件中前进。