Android RSS – RecyclerView Multiple Fields – Download,Parse,Show

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Oclemy

Nairobi, Kenya

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Oclemy

Shared a concept on: March 28, 20192019-03-28T11:09:20+00:00 2019-03-28T11:09:20+00:00

Android RSS – RecyclerView Multiple Fields – Download,Parse,Show

This is an android RSS example with XmlPullParser,AsyncTask ,HttpURLConnection and RecyclerView..We shall download RSS Feeds from a local website and then parse the feed.We then show parsed images and text news in our RecyclerView.

What we do :

Connect to Internet and make a HTTP GET request using HtttpURLConnection.
Download our data in the background thread.
WE use AsyncTask for our threading.
WE parse the downloaded xml feeds.
We shall be parsing using XmlPullParser.
We show our results in a RecyclerView.
The website we shall be parsing was hosted locally and it was a dummy wordpress site.

Lets start.

SECTION 1 : Our Dependencies and Manifest

Build.Gradle

Studio has added for us dependencies for AppCompat and Design support libraries.
Now lets add dependencies for CardView.
Our AdapterView shall consist of CardViews as our ViewItems.

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.tutorials.hp.recyclerviewrssmulti_items"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.3.0'
    compile 'com.android.support:design:23.3.0'
    compile 'com.android.support:cardview-v7:23.3.0'

}

AndroidManifest.xml

Remember we are downloading data from a network.
Hence we need to add permission to access the internet.
Or else Android won’t allow us establish connection.

<?xml version="1.0" encoding="utf-8"?>
<manifest 
    package="com.tutorials.hp.recyclerviewrssmulti_items">

    <uses-permission android_name="android.permission.INTERNET"/>

    <application
        android_allowBackup="true"
        android_icon="@mipmap/ic_launcher"
        android_label="@string/app_name"
        android_supportsRtl="true"
        android_theme="@style/AppTheme">
        <activity
            android_name=".MainActivity"
            android_label="@string/app_name"
            android_theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android_name="android.intent.action.MAIN" />

                <category android_name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

SECTION 2 : Our Data Object

Article.java

Represents a single article.
The article shall have various properties like name,description,title,date etc.

package com.tutorials.hp.recyclerviewrssmulti_items.m_DataObject;

public class Article {

    String title,description,date,link;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }
}

SECTION 3 : Our Networking and Parsing classes

Connector class

Main Responsibility : ESTABLISH CONNECTION.

Establishes connection to our server for us.
We then set up connection properties like Request method.
In this case we are making a HTTP GET request to our server.
We shall use HttpURLConnection so our only method shall return its instance .

package com.tutorials.hp.recyclerviewrssmulti_items.m_RSS;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class Connector {

    public static Object connect(String urlAddress)
    {
        try
        {
            URL url=new URL(urlAddress);
            HttpURLConnection con= (HttpURLConnection) url.openConnection();

            con.setRequestMethod("GET");
            con.setConnectTimeout(15000);
            con.setReadTimeout(15000);
            con.setDoInput(true);

            return con;

        } catch (MalformedURLException e) {
            e.printStackTrace();
            return ErrorTracker.WRONG_URL_FORMAT;

        } catch (IOException e) {
            e.printStackTrace();
            return ErrorTracker.CONNECTION_ERROR;
        }
    }

}

Downloader class

Main Responsibility : DOWNLOAD XML FEEDS.

We use our Connector class above to establish a connection.
If we have a connection then we download data XML feeds from server.
We download in background using AsyncTask to avoid freezing our user interface.
Meanwhile we show progress dialog while downloading.
We dismiss our progress dialog on completion.
Then we send this downloaded xml feeds to our Data Parser class for it to be processed.

package com.tutorials.hp.recyclerviewrssmulti_items.m_RSS;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;

public class Downloader extends AsyncTask<Void,Void,Object> {

    Context c;
    String urlAddress;
    RecyclerView rv;

    ProgressDialog pd;

    public Downloader(Context c, String urlAddress, RecyclerView rv) {
        this.c = c;
        this.urlAddress = urlAddress;
        this.rv = rv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd=new ProgressDialog(c);
        pd.setTitle("Fetch data");
        pd.setMessage("Fetching data...Please wait");
        pd.show();
    }

    @Override
    protected Object doInBackground(Void... params) {
        return downloadData();
    }

    @Override
    protected void onPostExecute(Object data) {
        super.onPostExecute(data);
        pd.dismiss();
        if(data.toString().startsWith("Error"))
        {
            Toast.makeText(c,data.toString(),Toast.LENGTH_SHORT).show();
        }else {
            //PARSE
            new RSSParser(c, (InputStream) data,rv).execute();
        }

    }

    private Object downloadData()
    {
        Object connection=Connector.connect(urlAddress);
        if(connection.toString().startsWith("Error"))
        {
            return connection.toString();
        }

        try
        {
            HttpURLConnection con= (HttpURLConnection) connection;
            int responseCode=con.getResponseCode();

            if(responseCode==con.HTTP_OK)
            {
                InputStream is=new BufferedInputStream(con.getInputStream());
                return is;
            }

            return ErrorTracker.RESPONSE_EROR+con.getResponseMessage();

        } catch (IOException e) {
            e.printStackTrace();
            return ErrorTracker.IO_EROR;
        }

    }
}

RSS Parser class

Main Responsibility : DOWNLOAD XML FEEDS.

It receives raw XML feeds from downloader class.
It then processes/parses these feeds.
We use XmlPullParser to parse the feeds.
It then fills an arraylist of Article Objects with our results.
It then sends this arraylist to adapter for binding purposes.

package com.tutorials.hp.recyclerviewrssmulti_items.m_RSS;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;

import com.tutorials.hp.recyclerviewrssmulti_items.m_DataObject.Article;
import com.tutorials.hp.recyclerviewrssmulti_items.m_UI.MyAdapter;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

public class RSSParser extends AsyncTask<Void,Void,Boolean> {

    Context c;
    InputStream is;
    RecyclerView rv;

    ProgressDialog pd;
    ArrayList<Article> articles=new ArrayList<>();

    public RSSParser(Context c, InputStream is, RecyclerView rv) {
        this.c = c;
        this.is = is;
        this.rv = rv;
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd=new ProgressDialog(c);
        pd.setTitle("Parse data");
        pd.setMessage("Parsing data...Please wait");
        pd.show();
    }

    @Override
    protected Boolean doInBackground(Void... params) {
        return this.parseRSS();
    }

    @Override
    protected void onPostExecute(Boolean isParsed) {
        super.onPostExecute(isParsed);
        pd.dismiss();
        if(isParsed)
        {
            //Bind
            rv.setAdapter(new MyAdapter(c,articles));

        }else {
            Toast.makeText(c,"Unable To Parse",Toast.LENGTH_SHORT).show();
        }
    }

    private Boolean parseRSS()
    {
        try
        {
            XmlPullParserFactory factory=XmlPullParserFactory.newInstance();
            XmlPullParser parser=factory.newPullParser();

            parser.setInput(is, null);
            int event=parser.getEventType();

            String value=null;

            articles.clear();
            Article article=new Article();

            do {
                String name=parser.getName();

                switch (event)
                {
                    case XmlPullParser.START_TAG:
                        if(name.equals("item"))
                        {
                            article=new Article();
                        }

                        break;

                    case XmlPullParser.TEXT:
                        value=parser.getText();
                        break;

                    case XmlPullParser.END_TAG:

                            if(name.equals("title"))
                            {
                                article.setTitle(value);

                            }
                            else if(name.equals("description"))
                            {
                               article.setDescription(value);

                            }else if(name.equals("pubDate"))
                            {
                                article.setDate(value);

                            }else if(name.equals("date"))
                            {
                               article.setDate(value);

                            }

                        if(name.equals("item"))
                        {
                            articles.add(article);
                        }
                        break;
                }

                event=parser.next();

            }while (event != XmlPullParser.END_DOCUMENT);

            return true;

        } catch (XmlPullParserException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;
    }
}

Error Tracker class

Main Responsibility : HELP US TRACK CONNECTION EXCEPTIONS AT RUNTIME

Consists of constants that we shall display when we encounter error at runtime.

package com.tutorials.hp.recyclerviewrssmulti_items.m_RSS;

public class ErrorTracker {

    public final static String WRONG_URL_FORMAT="Error : Wrong URL Format";
    public final static String CONNECTION_ERROR="Error : Unable To Establish Connection";
    public final static String IO_EROR="Error : Unable To Read";
    public final static String RESPONSE_EROR="Error : Bad Response - ";
}

SECTION 3 : ReyclerView classes

View Holder class

Main Responsibility : HOLD VIEWS FOR RECYCLING.

In this case textviews.
Subclasses RecyclerView.ViewHolder.

package com.tutorials.hp.recyclerviewrssmulti_items.m_UI;

import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

import com.tutorials.hp.recyclerviewrssmulti_items.R;

public class MyHolder extends RecyclerView.ViewHolder {

    TextView titleTxt,descTxt,dateTxt;

    public MyHolder(View itemView) {
        super(itemView);

        titleTxt= (TextView) itemView.findViewById(R.id.titleTxt);
        descTxt= (TextView) itemView.findViewById(R.id.descTxt);
        dateTxt= (TextView) itemView.findViewById(R.id.dateTxt);

    }
}

Adapter class

Main Responsibility : HELPS US BIND CUSTOM DATA TO RECYCLERVIEW.

Subclasses RecyclerView.Adapter
Binds our dataset to our views.
Shall receive an arraylist and a context.

package com.tutorials.hp.recyclerviewrssmulti_items.m_UI;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.tutorials.hp.recyclerviewrssmulti_items.R;
import com.tutorials.hp.recyclerviewrssmulti_items.m_DataObject.Article;

import java.util.ArrayList;

public class MyAdapter extends RecyclerView.Adapter<MyHolder> {

    Context c;
    ArrayList<Article> articles;

    public MyAdapter(Context c, ArrayList<Article> articles) {
        this.c = c;
        this.articles = articles;
    }

    @Override
    public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v= LayoutInflater.from(c).inflate(R.layout.model,parent,false);
        return new MyHolder(v);
    }

    @Override
    public void onBindViewHolder(MyHolder holder, int position) {

        Article article=articles.get(position);

        holder.titleTxt.setText(article.getTitle());
        holder.descTxt.setText(article.getDescription());
        holder.dateTxt.setText(article.getDate());
    }

    @Override
    public int getItemCount() {
        return articles.size();
    }
}

SECTION 4 : Our Activity

MainActivity class.

Main Responsibility : LAUNCH OUR APP.

We shall reference the views like RecyclerView and Floating action button here,from our XML Layouts.
We then execute our Downloader class when Floating action button is clicked.
We shall also define here our feeds url and parse the data.

package com.tutorials.hp.recyclerviewrssmulti_items;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import com.tutorials.hp.recyclerviewrssmulti_items.m_RSS.Downloader;

public class MainActivity extends AppCompatActivity {

    final static String urlAddress="http://10.0.2.2/galacticnews/index.php/feed";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

        final RecyclerView rv= (RecyclerView) findViewById(R.id.rv);
        rv.setLayoutManager(new LinearLayoutManager(this));

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                new Downloader(MainActivity.this,urlAddress,rv).execute();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

SECTION 5 : Our Layouts

ActivityMain.xml Layout.

Inflated as our activity’s view.
Includes our content main.

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    
    
    android_layout_width="match_parent"
    android_layout_height="match_parent"
    android_fitsSystemWindows="true"
    tools_context="com.tutorials.hp.recyclerviewrssmulti_items.MainActivity">

    <android.support.design.widget.AppBarLayout
        android_layout_width="match_parent"
        android_layout_height="wrap_content"
        android_theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android_id="@+id/toolbar"
            android_layout_width="match_parent"
            android_layout_height="?attr/actionBarSize"
            android_background="?attr/colorPrimary"
            app_popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.design.widget.FloatingActionButton
        android_id="@+id/fab"
        android_layout_width="wrap_content"
        android_layout_height="wrap_content"
        android_layout_gravity="bottom|end"
        android_layout_margin="@dimen/fab_margin"
        android_src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

ContentMain.xml Layout.

Defines our view hierarchy.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    
    
    android_layout_width="match_parent"
    android_layout_height="match_parent"
    android_paddingBottom="@dimen/activity_vertical_margin"
    android_paddingLeft="@dimen/activity_horizontal_margin"
    android_paddingRight="@dimen/activity_horizontal_margin"
    android_paddingTop="@dimen/activity_vertical_margin"
    app_layout_behavior="@string/appbar_scrolling_view_behavior"
    tools_context="com.tutorials.hp.recyclerviewrssmulti_items.MainActivity"
    tools_showIn="@layout/activity_main">

    <android.support.v7.widget.RecyclerView
        android_id="@+id/rv"
        android_layout_width="match_parent"
        android_layout_height="wrap_content"
         />
</RelativeLayout>

Model.xml Layout.

Inflated as our AdapterView’s viewitems.

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView 
    android_orientation="horizontal" android_layout_width="match_parent"
    
    android_layout_margin="10dp"
    card_view_cardCornerRadius="5dp"
    card_view_cardElevation="5dp"
    android_layout_height="200dp">

    <LinearLayout
        android_orientation="vertical"
        android_layout_width="match_parent"
        android_layout_height="match_parent">
        <TextView
            android_layout_width="match_parent"
            android_layout_height="wrap_content"
            android_textAppearance="?android:attr/textAppearanceLarge"
            android_text="Title"
            android_id="@+id/titleTxt"
            android_padding="10dp"
            android_textColor="@color/colorAccent"
            android_textStyle="bold"
            android_layout_alignParentLeft="true"
            />

            <TextView
                android_layout_width="wrap_content"
                android_layout_height="wrap_content"
                android_textAppearance="?android:attr/textAppearanceLarge"
                android_text="Description....................."
                android_lines="3"
                android_id="@+id/descTxt"
                android_padding="10dp"
                android_layout_alignParentLeft="true"
                />

            <TextView
                android_layout_width="wrap_content"
                android_layout_height="wrap_content"
                android_textAppearance="?android:attr/textAppearanceMedium"
                android_text="Date"
                android_textStyle="italic"
                android_id="@+id/dateTxt" />
    </LinearLayout>

</android.support.v7.widget.CardView>

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Oclemy

Android RSS – RecyclerView Multiple Fields – Download,Parse,Show

SECTION 1 : Our Dependencies and Manifest

SECTION 2 : Our Data Object

SECTION 3 : Our Networking and Parsing classes

SECTION 3 : ReyclerView classes

SECTION 4 : Our Activity

SECTION 5 : Our Layouts

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