Java XStream CannotResolveClassException

Question

I am trying to parse an XML file to objects using XStream but I am getting this exception:

Exception in thread "main" com.thoughtworks.xstream.mapper.CannotResolveClassException: servers at com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:56) at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30) at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:55) [...]

Here is my XML:

  <servers>
    <server>
      <ip>10.196.113.27</ip> 
    </server>
    <server>
      <ip>10.196.113.31</ip> 
    </server>
  </servers>

Here is my code:

public class ServerIP {
    private String ip;

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }
}

public class ServerHandler {

    private String fileName = "servers.xml";
    private String path = "J:\\workspace\\LOG730\\src\\Q3\\";
    private XStream xstream = new XStream(new DomDriver());

    public void readFromXML() {
        try {
            FileInputStream fis = new FileInputStream(path + fileName);
            ServerIP server = (ServerIP) xstream.fromXML(fis, new ServerIP());
            System.out.println("Host: " + server.getIp());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

The exception is triggered by this:

    ServerHandler serverHandler = new ServerHandler();
    serverHandler.readFromXML();

Answer 1

Try to add a class Servers to hold your ServerIP instances and to add this lines:

xstream.alias("servers", Servers.class);
xstream.alias("server", ServerIP.class);

Here you can find a simple tutorial on the aliases: http://x-stream.github.io/alias-tutorial.html