Question

我几乎没有使用分隔符的经验，我需要读取一个文本文件，该文件存储多个对象，这些对象的数据以逗号（“，”）分隔的单行存储。然后使用单独的字符串创建一个添加到arraylist的新对象。

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

我使用Scanner读取文件，但是我发现没有找到行错误，整个文件存储在一个字符串中：

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();

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();

Answer 2

我想你想调用.next()，它返回一个String而不是.nextLine()。您的.nextLine()来电正在超越当前行。

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();

Answer 3

您应该使用next();

的nextLine();

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

注意以下几行：

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

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

Answer 4

您还可以使用String.split（）函数将字符串转换为字符串数组，然后针对您的值遍历每个字符串。

How to convert comma-separated String to ArrayList?有关详细信息，请参阅此内容。

Answer 5

一个问题是：

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

hasNext()

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

你正在做nextLine（）三次。我认为你需要做的是，读取线和分割线。

Answer 6

以上所有答案都是正确的，实际上是相同的。但是，重要的一点是每个人都应该记住Scanner的缓冲区大小仅为1024。这意味着如果定界文本的长度更大，则解析将停止。

因此，对给定解决方案进行了一些增强，请使用BufferedReader而不是将文件直接传递到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();

在读取文件时使用分隔符

6 个答案: