使用扫描仪分析文件中的输入。 JAVA

Question

我是java的新手，并且正在创建一个文件目录，该目录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，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。 我有一种将影片打印到控制台的方法，但是我遇到了正确格式化影片的问题。 电影信息应采用以下格式：

   Star Wars     PG    1977   5 stars  1/5/2018

每列应正确对齐。 标题，等级和年份应保持对齐； 星号和日期正确对齐。

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，事情就变得混乱了。 这是我的代码，我相信问题出在listMovies方法中，我尝试格式化输出，但是我包括了所有代码，以防其他地方发生混乱。

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（一次运行程序）后的输出，应该是这样的样子：

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

这是运行两次之后的结果：

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次后的结果：

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

如果我正确理解了该问题，则解决方案非常简单：在dirOut.hasNext（）循环中的System.out.printf（）下面添加以下行。

dirOut.nextLine();

您的输入模式有两行； 这个额外的nextLine（）可以正确地浏览文件。