使用分隔符读取文件

Question

我很少使用分隔符，需要读取一个文本文件，其中存储了一些对象，这些对象的数据以逗号（","）分隔在单行中。然后将分隔的字符串用于创建一个新对象，该对象添加到一个ArrayList中。

Amadeus,Drama,160 Mins.,1984,14.83
As Good As It Gets,Drama,139 Mins.,1998,11.3
Batman,Action,126 Mins.,1989,10.15
Billy Elliot,Drama,111 Mins.,2001,10.23
Blade Runner,Science Fiction,117 Mins.,1982,11.98
Shadowlands,Drama,133 Mins.,1993,9.89
Shrek,Animation,93 Mins,2001,15.99
Snatch,Action,103 Mins,2001,20.67
The Lord of the Rings,Fantasy,178 Mins,2001,25.87

我正在使用Scanner读取文件，但是遇到了"没有找到行"的错误，并且整个文件都被存储为一个字符串：

Scanner read = new Scanner (new File("datafile.txt"));
read.useDelimiter(",");
String title, category, runningTime, year, price;

while (read.hasNext())
{
   title = read.nextLine();
   category = read.nextLine();
   runningTime = read.nextLine();
   year = read.nextLine();
   price = read.nextLine();
   System.out.println(title + " " + category + " " + runningTime + " " +
                      year + " " + price + "\n"); // just for debugging
}
read.close();

- Robert Spratlin

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Сй┐ућеread.next()УђїСИЇТў»nextLine()сђѓ - Jeroen Vannevel

Answer 1

使用read.next()而不是read.nextLine()

   title = read.next();
   category = read.next();
   runningTime = read.next();
   year = read.next();
   price = read.next();

- muffy

Answer 2

我认为您想调用.next()方法，它返回一个字符串，而不是使用.nextLine() 方法。您的.nextLine() 调用使当前行向后移动了。

Scanner read = new Scanner (new File("datafile.txt"));
   read.useDelimiter(",");
   String title, category, runningTime, year, price;

   while(read.hasNext())
   {
       title = read.next();
       category = read.next();
       runningTime = read.next();
       year = read.next();
       price = read.next();
     System.out.println(title + " " + category + " " + runningTime + " " + year + " " + price + "\n"); //just for debugging
   }
   read.close();

- majorbanzai

Answer 3

以上所有答案都是正确的，并且实际上相同。但是，每个人都应该记住一个重要点，即 Scanner 只有1024个缓冲区大小。这意味着如果分隔文本的长度更长，解析将停止。

因此，在给定的解决方案上进行小幅改进，使用 BufferedReader 而不是直接将文件传递给 Scanner 。示例：

    BufferedReader in = new BufferedReader(new FileReader("datafile.txt"), 16*1024);
    Scanner read = new Scanner(in);
    read.useDelimiter(",");
    String title, category, runningTime, year, price;

    while(read.hasNext())
    {
        title = read.next();
        category = read.next();
        runningTime = read.next();
        year = read.next();
        price = read.next();
        System.out.println(title + " " + category + " " + runningTime + " " + year + " " + price + "\n"); //just for debugging
    }
    read.close();

- user846316

Answer 4

在使用nextLine();的地方，您应该使用next();

请查看教程：http://docs.oracle.com/javase/tutorial/essential/io/scanning.html

请注意以下这些行：

try {
   s = new Scanner(new BufferedReader(new FileReader("xanadu.txt")));

   while (s.hasNext()) {
   System.out.println(s.next());
}

- mcalex

Answer 5

您也可以使用 String.split() 函数将字符串转换为字符串数组，然后迭代每个字符串以获取您的值。

如何将逗号分隔的字符串转换为 ArrayList？ 有关更多详细信息，请参见此页面。

- Aniket Inge

Answer 6

一个问题是：

while(read.hasNext())
   {
       title = read.nextLine();
       category = read.nextLine();
       runningTime = read.nextLine();

hasNext()

如果此扫描器在其输入中有另一个标记，则返回true。不是整行。您需要使用hasNextLine()。

您正在执行三次nextLine()。我认为您需要做的是读取该行并拆分该行。

- kosa