Question

I am using opencsv to parse text file and generate List<String[]> now I want to generate XML from List<String[]> and so my question is do we have any 3rd Party Libraries that does that conversion, if not, what would be an better approach to solve the issue.

Here is the Parsing Logic:

    public class ParseFile {

    public ParseFile() {

    }

    public void getQuotes() {
        String fileName = "C:\\GS.txt";
        try {
            CSVReader reader = new CSVReader(new FileReader(fileName), '\t');
            String[] nextLine;
            List<String[]> dataList = new ArrayList<String[]>();
            dataList = reader.readAll();
        } catch (Exception e) {
        }
    }

    public static void main(String args[]) {
        ParseFile test = new ParseFile();
        test.getQuotes();
        System.out.println("Parsing Done Successfully....");
    }
}

So my txt file looks like:

Header Information: ContractDate Trader  Quantity
1st Line of Data:   03/23/12     GS      100

and I need to have XML Structure like:

<root>
  <entry id='1'>
    <ContractDate>03/23/12</ContractDate>
    <Trader>GS</Trader>
    <Quantity>100</Quantity>
  </entry>
</root>

Answer 1

You don’t explicitly require a 3rd party library to generate your rather simple XML format. You could simply write a to a StringBuffer object:

...
StringBuffer sb = new StringBuffer();
sb.append("<root>");
for (String[] row: dataList) {
  sb.append("<entry>");
  sb.append("<ContractDate>").append(row[0]).append("</ContractDate>");
  // etc...
  sb.append("</entry>");
}
sb.append("</root>");
...

However, I’m not necessarily advocating it. I personally recommend Simple XML. Create a POJO to model your rows (I won’t include all properties in my example):

@Root
public class Entry {

  @Element
  private String trader;

  @Attribute
  private int id;

  public Entry() {
    super();
  }  

  public String getTrader() {
    return text;
  }

  public void setTrader(String trader) {
    this.trader = trader;
  }

  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
}

@Root(name="root")
public class Entries {
   @ElementList(inline=true)
   List<Entry> entries;

   public Entries(List<Entry> entries) {
     this.entries = entries;
   }
}

It’s certainly some extra work up-front, but for non-trivial programs, having proper Java classes to represent the data models makes a lot of sense and provides greater flexibility, and code clarity.

To save save as XML you do this:

 List<Entry> entryList = new ArrayList();
 int entryCount = 0;
 Serializer serializer = new Persister();
 for (String[] row: dataList) {
   Entry entry = new Entry();
   entry.setTrader(row[1]);
   entry.setId(++entryCount);
   entryList.add(entry);
 }
 File result = new File("entries.xml");
 serializer.write(new Entries(entryList), result);

The Simple XML library gives you a lot of flexibility. You can also load up the XML file back into a list of Entry objects.