我如何访问arraylist中的列表元素

Question

I am parsing xml from web service, i want to use xml values as a arraylist

 eElement.getElementsByTagName(Lyr_NAME) values are  Traffic , Satellite , Hybrid , Satellite 2

 eElement.getElementsByTagName(Lyr_URL) values are  url1 , url2 , url3, url4

Lyr_LAYER_TYPE and Lyr_FIELD has 4 elements

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

         for (int i = 0; i < nl.getLength(); i++) {

        Node nNode = nl.item(i);
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {

            Element eElement = (Element) nNode;

            LayerNames.add(0, eElement.getElementsByTagName(Lyr_NAME).item(0).getTextContent());
            LayerNames.add(1,eElement.getElementsByTagName(Lyr_URL).item(0).getTextContent());
            LayerNames.add(2,eElement.getElementsByTagName(Lyr_LAYER_TYPE).item(0).getTextContent());
            LayerNames.add(3,eElement.getElementsByTagName(Lyr_FIELD).item(0).getTextContent());

        }

    }

Layer values are coming rapidly. But when i use get to access elements in arraylist it always return Lyr_NAME elements, then when i write LayerNames[0] Android Studio didn't resolve type. My log is;

    Log.e("Array List Result",LayerNames.get(0));

My question is how can i access to Lyr_URL , Lyr_TYPE or Lyr_FIELD ;?

Thanks in advance

Answer 1

You cannot get in List. You can use Map.

Map<String,String> LayerNames = new HashMap<String,String>();
        for (int i = 0; i < nl.getLength(); i++) {
            Node nNode = nl.item(i);
            if (nNode.getNodeType() == Node.ELEMENT_NODE) {
                Element eElement = (Element) nNode;
                LayerNames.put(Lyr_NAME, eElement.getElementsByTagName(Lyr_NAME).item(0).getTextContent());
                LayerNames.put(Lyr_URL,eElement.getElementsByTagName(Lyr_URL).item(0).getTextContent());
                LayerNames.put(Lyr_LAYER_TYPE,eElement.getElementsByTagName(Lyr_LAYER_TYPE).item(0).getTextContent());
                LayerNames.put(Lyr_FIELD,eElement.getElementsByTagName(Lyr_FIELD).item(0).getTextContent());
            }
        }

Log.e("Map Result",LayerNames.get(Lyr_URL));

Answer 2

You neet to write get functions into Lyr_NAME classes' and return the attributes of the class with that functions. Than, you should add the same functions for the own attributes of Lyr_URL . You can just simply:

LayerNames.get(0).getLyr_URL().getURL1()
LayerNames.get(0).getTraffic() 
// etc.

Answer 3

By populating arraylist with index, you are overwriting the existing elements and hence you will just left with last elements in the xml if there are multiple tags. Instead you should do something like:

for (int i = 0; i < nl.getLength(); i++) {
    Node nNode = nl.item(i);
    if (nNode.getNodeType() == Node.ELEMENT_NODE) {
        Element eElement = (Element) nNode;
        LayerNames.add(eElement.getElementsByTagName(Lyr_NAME).item(0).getTextContent());
        LayerNames.add(eElement.getElementsByTagName(Lyr_URL).item(0).getTextContent());
        LayerNames.add(eElement.getElementsByTagName(Lyr_LAYER_TYPE).item(0).getTextContent());
        LayerNames.add(eElement.getElementsByTagName(Lyr_FIELD).item(0).getTextContent());

    }
}

And then you could do something like:

for (int i = 0; i<LayerNames.size(); i+=4) {
    for (int j = i; j< i+4;j++) {
         Log.e("Array List Result", LayerNames.get(j));
    }
}

if you think it's just going to be once, then you could do something like:

for (int i = 0; i<LayerNames.size(); i+=4) {
         Log.e("Array List Result", LayerNames.get(j));
}

It will print layer name followed by url followed by layer type followed by field.