Question

I have to write an XML file using java.The contents should be written from a map.The map contains items as key and their market share as value.I need to build an XML file withe two tags.I will use this XML to build a piechart using amcharts.Can anyone help with an existing code?

<xml>
<pie>
    <slice title="<Map key1>"><Map Value1></slice>
    <slice title="<Map key2>"><Map Value2></slice>
    <slice title="<Map key1>"><Map Value3></slice>
     .
     .
     .
    <slice title="<Map keyn>"><Map Valuen></slice>
 </pie>

Answer 1

There are a number of ways to do this using the standard API. (Insert your own caveats about verbosity and the factory pattern.)

You can use the XMLStreamWriter to encode the data:

XMLOutputFactory factory = XMLOutputFactory
    .newInstance();
XMLStreamWriter writer = factory.createXMLStreamWriter(
    stream, "UTF-8");
try {
  writer.writeStartDocument("UTF-8", "1.0");
  writer.writeStartElement("pie");
  for (Entry<String, String> entry : map.entrySet()) {
    writer.writeStartElement("slice");
    writer.writeAttribute("title", entry.getKey());
    writer.writeCharacters(entry.getValue());
    writer.writeEndElement();
  }
  writer.writeEndElement();
  writer.writeEndDocument();
} finally {
  writer.close();
}

Alternatively, you could build a DOM document (not recommended) and emit that, or use JAXB binding to marshal/unmarshal data (tutorial).

Sample annotated JAXB object:

@XmlRootElement(name = "pie")
public class Pie {

  @XmlElement(name = "slice")
  public List<Slice> slices = new ArrayList<Slice>();

  public Pie() {
  }

  public Pie(Map<String, String> sliceMap) {
    for (Map.Entry<String, String> entry : sliceMap
        .entrySet()) {
      Slice slice = new Slice();
      slice.title = entry.getKey();
      slice.value = entry.getValue();
      slices.add(slice);
    }
  }

  static class Slice {
    @XmlAttribute
    public String title;
    @XmlValue
    public String value;
  }

}

Test code:

Map<String, String> slices = new HashMap<String, String>();
slices.put("Title 1", "100");
slices.put("Title 2", "200");

Pie pie = new Pie(slices);
JAXB.marshal(pie, System.out);

There are a host of third party APIs that can do the same jobs and various templating options have already been mentioned.