Need to call a method to populate my list, then have that list bound to rich tree

[Matt Kohanek]

I have the method written to populate the list, and when I call the method and print the alues it doesshow that the list was populated like I want. So I thought the next part would be simple, I would just have setter and getter for the list and bind this to my tree. But when i did this I get an error saying

roots="#{tempTreeBean.ids}": Error reading 'ids' on type testContainer.Temp

So it looks like to me that teh tree is trying to pull the vaues from my list before the method to populate the list is being invoked. So how do I tell my rich tree to call the method to load the list before trying to add that list as the branches of the tree? I tried just putting a method call in the getter to load the list, but no good. I am wondering if there is just some attribute I can add to the rich tree tag that will tell it to first call the method to load the lst with values, and then try to use that list to populate the branches

edit - essentially Im needing to tell my jsf page "invoke this method to load the list before you do anything else, then use this list to populate the tree"

[Kavita Tipnis]

First check whether your getter/setter has a valid signature. I think it should not be static.
If you do not wish to call the method that populates your list everytime you invoke the getter put it in the BackingBean constructor

TempTreeBean(){
loadList()
}

If your TempTreeBean is in request scope, the loadList() will be invoked per request, if it is in session scope then per session

[Matt Kohanek]

No, the getter isnt static.
Here is the code:

public class Temp {

	List<String> ids  = new ArrayList<String>();

	/*public static void main(String[] args) {
		//getIds();
		print();		
	}	*/
	
	public void loadNodes() {
				
		DeviceCollectionXMLAO access = new DeviceCollectionXMLAO();
		HttpClientMethods method = new HttpClientMethods();
        DeviceCollection deviceCollection = null;
   
        try {
			deviceCollection = access.readXML(method.Response(null));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		//System.out.println("printing deviceCollection = access.readXML(method.getResponseBodyAsStream(null));: " 
				//+ deviceCollection.toString());        
		
		for (Device device : deviceCollection.getDevices()){   
		    String x = device.getDeviceId();   
		    ids.add(x); 
		    System.out.println(ids);
		}		
		
	}

	public List<String> getIds() {
		loadNodes();
		return ids;
	}

	public void setIds(List<String> ids) {
		this.ids = ids;
	}

	public void print(){
		System.out.println("Printing ids list: "+ids);
	}
}    

When I call the loadNodes method followed by the print method it prints out the deviceIds like I expect, so it looks like everything is working as intended. However if I bind ids to my tree it gives me this stack:

javax.el.ELException: /test/treetest.xhtml @18,75 roots="#{tempTreeBean.ids}": Error reading 'ids' on type testContainer.Temp
com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:76)
org.richfaces.component.html.HtmlRecursiveTreeNodesAdaptor.getRoots(HtmlRecursiveTreeNodesAdaptor.java:181)
org.richfaces.component.UIRecursiveTreeNodesAdaptor.getData(UIRecursiveTreeNodesAdaptor.java:55)
org.richfaces.component.UITreeNodesAdaptor$1.getData(UITreeNodesAdaptor.java:54)
org.richfaces.model.StackingTreeModel.getDataModel(StackingTreeModel.java:83)
org.richfaces.model.StackingTreeModel.doWalk(StackingTreeModel.java:309)
org.richfaces.model.StackingTreeModel.walk(StackingTreeModel.java:381)
org.richfaces.component.UITree.walk(UITree.java:422)

Thats not all of it but it is the beginning. But when I click on line 76 or 181 there it tells me the source isnt attached, and when I try to figure out where the source is to attahc I have no luck with it.

Someone else has suggested using @PostConstruct annotation to resolve this so Im looking into that now but it is the first time Ive heard of that

[Kavita Tipnis]

For debugging purpose, just add to ids manually(as in "1","2") , that should just be a 2 min work, check if that is throwing any error

[Matt Kohanek]

I did try that actually and it did work. ANd when I tried the @PostConstruct I now get

javax.servlet.ServletException: java.lang.IllegalArgumentException: Invalid PostConstruct annotation
javax.faces.webapp.FacesServlet.service(FacesServlet.java:277)
org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)
org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:390)
org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:517)

So now my only guess is that method just doesnt want to work when invoked from the server, only the client, but that is just a pure guess really.

Here is the method that is giving all the hassle:

public class Temp {

	List<String> ids  = new ArrayList<String>();

	/*public static void main(String[] args) {
		//getIds();
		print();		
	}	*/
	
	@PostConstruct
	public void loadNodes() throws IOException, Exception {
				
		DeviceCollectionXMLAO access = new DeviceCollectionXMLAO();
		HttpClientMethods method = new HttpClientMethods();
        DeviceCollection deviceCollection = null;
   

			deviceCollection = access.readXML(method.Response(null));


		//System.out.println("printing deviceCollection = access.readXML(method.getResponseBodyAsStream(null));: " 
				//+ deviceCollection.toString());        
		
		for (Device device : deviceCollection.getDevices()){   
		    String x = device.getDeviceId();   
		    ids.add(x); 
		    //System.out.println(ids);
		}		
		
	}

	public List<String> getIds() {
		//loadNodes();
		return ids;
	}

	public void setIds(List<String> ids) {
		this.ids = ids;
	}

	public void print(){
		System.out.println("Printing ids list: "+ids);
	}
}    

Then I have a main method in another class to invoke the loadnodes and print methods:

public static void main(String[] args) throws IOException, Exception {
		// TODO Auto-generated method stub
		Temp temp = new Temp();
		temp.loadNodes();
		temp.print();
		
	}

}    

And the result is
Printing ids list: [exampleDevice1]

Here are the other two classes that are instanced in temp:

public class HttpClientMethods {

	static String devicesUrl = "http://webc-apps.ni.com/measure/1.01/devices";

	public InputStream Response(InputStream x) throws IOException{
		// Create an instance of HttpClient.
		 HttpClient client = new HttpClient();
		
	 	 // Create a method instance.
	     GetMethod method = new GetMethod(devicesUrl);
	     
	     InputStream responseBody = null;
	     
	     try {
			 // Execute the method.
			 int statusCode = client.executeMethod(method);
			 //System.out.println( method.getStatusCode());
			
			 if (statusCode != HttpStatus.SC_OK) {
			     System.out.println("Method failed: " + method.getStatusLine());
			 }
			
			 // Read the response body.
			 responseBody = method.getResponseBodyAsStream();
			 //System.out.println("printing current value of method.getResponseBodyAsString from httpclient class "+
					 //method.getResponseBodyAsString());
			     } catch (Exception e) {
			             // TODO Auto-generated catch block
			                 e.printStackTrace();
			         }
			     
	    //System.out.println("printing InputStream responseBody from httpclient class: " + responseBody);
	    
		return responseBody;
	     
	}    

public class DeviceCollectionXMLAO {

	public DeviceCollection readXML(InputStream xml) throws Exception { 
	    Serializer serializer = new Persister(); 

	    DeviceCollection deviceCollection = null; 
	    deviceCollection = serializer.read(DeviceCollection.class, xml); 
	    xml.close(); 
	    return deviceCollection; 
	}     

But now were getting into my other problem, which is that it is not easy to just look at all of this code and find the problem, one would need to test it, which is what I am supposed to be doing. Ce la vie

[John Arevalo]

PostConstruct annotation should be applied to methods without throws Exceptions, void return and no params. Only one method can be postconstruct