JAVA - CSV导入到ArrayList的 [英] JAVA - import CSV to ArrayList

问题描述

我想进口 CSV 文件复制到的ArrayList 使用的StringTokenizer ：

I'm trying import CSV file to Arraylist using StringTokenizer:

public class Test
{
  public static void main(String [] args)
  {
    List<ImportedXls> datalist = new ArrayList<ImportedXls>();

    try
    {
      FileReader fr = new FileReader("c:\\temp.csv");
      BufferedReader br = new BufferedReader(fr);
      String stringRead = br.readLine();

      while( stringRead != null )
      {
        StringTokenizer st = new StringTokenizer(stringRead, ",");
        String docNumber = st.nextToken( );
        String note = st.nextToken( );  /** PROBLEM */
        String index = st.nextToken( ); /** PROBLEM */

        ImportedXls temp = new ImportedXls(docNumber, note, index);
        datalist.add(temp);

        // read the next line
        stringRead = br.readLine();
      }
      br.close( );
    }
    catch(IOException ioe){...}

    for (ImportedXls item : datalist) {
      System.out.println(item.getDocNumber());
    }
  }
}

我不明白是怎么的nextToken 的作品，因为如果我把初始化三个变量（ docNumber ， 注意和首页）为的nextToken（），它失败于：

I don't understand how the nextToken works, because if I keep the initialize three variables (docNumber, note and index) as nextToken(), it fails on:

Exception in thread "main" java.util.NoSuchElementException
    at java.util.StringTokenizer.nextToken(Unknown Source)
    at _test.Test.main(Test.java:32)

如果我只保留docNumber，它的工作原理。你能帮助我吗？

If I keep docNumber only, it works. Could you help me?

推荐答案

看来，一些输入文件的行具有小于3逗号分隔fields.You应经常检查，如果标记生成器有更多的令牌（StringTokenizer.hasMoreTokens） ，除非你是100％肯定您的输入是正确的。

It seems that some of the rows of your input file have less then 3 comma separated fields.You should always check if tokenizer has more tokens (StringTokenizer.hasMoreTokens), unless you are are 100% sure your input is correct.

CSV文件正确解析也不是那么简单的任务。为什么不使用库，可以做的非常好 - http://opencsv.sourceforge.net/

CORRECT parsing of CSV files is not so trivial task. Why not to use a library that can do it very well - http://opencsv.sourceforge.net/ ?

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