JAVA - 将CSV导入ArrayList [英] JAVA - import CSV to ArrayList

问题描述

我尝试使用 StringTokenizer 将 CSV 文件导入到 Arraylist $ c>：

  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）; 
 
 //读取下一行
 stringRead = br.readLine（）; 
} 
 br.close（）; 
} 
 catch（IOException ioe）{...} 
 
 for（ImportedXls item：datalist）{
 System.out.println（item.getDocNumber（） ）; 
} 
} 
} 
  

因为如果我保持初始化三个变量（ docNumber ， note code>和 ）作为 nextToken（），它失败：

线程main中的异常java.util.NoSuchElementException
在java.util.StringTokenizer.nextToken（未知源）
at _test .Test.main（Test.java:32）


如果我只保留docNumber，你能帮我吗？

解决方案

看起来你的输入文件的一些行少于3个逗号分隔的字段。应该总是检查tokenizer是否有更多的令牌（StringTokenizer.hasMoreTokens），除非你是100％肯定你的输入是正确的。

CORRECT解析CSV文件不是那么简单任务。为什么不使用可以做得很好的图书馆 - http://opencsv.sourceforge.net/ ？

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());
    }
  }
}

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)

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

解决方案

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.

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/ ?

这篇关于JAVA - 将CSV导入ArrayList的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！