How to filter an RSS feed with keywords?

Question

I've built an android app with an RSS feed as the homepage. One of my app's features is to have multiple users with different preferences. Is it possible for the user to enter keywords that they are interested in and then to use those keywords to filter the news provided by the RSS feed? I'm fairly new to android programming and I'm completely stuck on this. I'd really appriciate any help or ideas!

The main section of code for my RSS feed (Just ask if you need more code):

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.provider.DocumentsContract;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import static android.R.attr.data;

/**
 * Created by Joe on 04/03/2017.
 */
public class ReadRss extends AsyncTask<Void,Void,Void>{
    ArrayList<FeedItem>feedItems;
    RecyclerView recyclerView;
    Context context;
    static ArrayList<String>address;

    static {
        address=new ArrayList<>();
        address.add("https://www.bloomberg.com/politics/feeds/site.xml");
        address.add("https://www.bloomberg.com/feeds/podcasts/etf_report.xml");
    }
    //String address="https://www.bloomberg.com/feeds/podcasts/etf_report.xml";
   // String address2="www.bloomberg.com/politics/feeds/site.xml";
    ProgressDialog progressDialog;
    URL url;
    public ReadRss(Context context, RecyclerView recyclerView){
        this.recyclerView=recyclerView;
        this.context=context;
        progressDialog=new ProgressDialog(context);
        progressDialog.setMessage("Loading...");
    }

    @Override
    protected void onPreExecute() {
        progressDialog.show();
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(Void aVoid) {

        super.onPostExecute(aVoid);
        progressDialog.dismiss();
        MyAdapter adapter=new MyAdapter(context,feedItems);
        recyclerView.setLayoutManager(new LinearLayoutManager(context));
        recyclerView.addItemDecoration(new VerticalSpace(50));
        recyclerView.setAdapter(adapter);
    }

    @Override
    protected Void doInBackground(Void... params) {
        ProcessXml(Getdata());
        return null;
    }

    private void ProcessXml(ArrayList<Document> data) {
        if (data != null) {
            feedItems = new ArrayList<>();
            for (Document doc : data) {
                Element root = doc.getDocumentElement();
                Node channel = root.getChildNodes().item(0);
                NodeList items = channel.getChildNodes();
                for (int i = 0; i < items.getLength(); i++) {
                    Node currentchild = items.item(i);
                    if (currentchild.getNodeName().equalsIgnoreCase("item")) {
                        FeedItem item = new FeedItem();
                        NodeList itemchilds = currentchild.getChildNodes();
                        for (int j = 0; j < itemchilds.getLength(); j++) {
                            Node current = itemchilds.item(j);
                            if (current.getNodeName().equalsIgnoreCase("title")) {
                                item.setTitle(current.getTextContent());
                            } else if (current.getNodeName().equalsIgnoreCase("description")) {
                                item.setDescription(current.getTextContent());
                            } else if (current.getNodeName().equalsIgnoreCase("pubDate")) {
                                item.setPubDate(current.getTextContent());
                            } else if (current.getNodeName().equalsIgnoreCase("link")) {
                                item.setLink(current.getTextContent());
                            }

                        }
                        feedItems.add(item);
                        Log.d("itemTitle", item.getTitle());
                        Log.d("itemDescription", item.getTitle());
                        Log.d("itemLink", item.getTitle());
                        Log.d("itemPubDate", item.getTitle());
                    }
                }
            }
        }
    }

    public ArrayList<Document> Getdata(){
        ArrayList<Document> documents = new ArrayList<>();
        for (String addr: address) {
            try {
                url = new URL(addr);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                InputStream inputStream = connection.getInputStream();
                DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = builderFactory.newDocumentBuilder();
                Document xmlDoc = builder.parse(inputStream);
                documents.add(xmlDoc);
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }
        }
        return documents;
    }
}

Answer 1

You should parse xml file with selected parser (you chosen DOM parse, but I highly recommend you check SimpleXML). Then fill your List with parsed data. Create new method which will check if object contains/equals needed tag.

  List<FeedItem> feeds = new ArrayList<>();
    for(FeedItem feedItem : feedItems){
        if (feedItem.getTitle().equals("tag which you want")){
            feeds.add(feedItem);
        }
    }
    return feeds;