Android JSON, HttpURLConnection, AsyncTask and ListView Examples

| Page Views: 238

Android JSON, ListView and HttpURLConnection Tutorial and Examples.

In this article we want to look at several examples of how to use three technologies:

  • JSON
  • HttpURLConnection
  • AsyncTask
  • ListView
What is JSON

JSON in full is JavaScript Object Notation. It is a language-independent data format that expresses JSON objects as human-readable lists of properties(name-value pairs).

JSON is very easy to read, lightweight and fast.

Learn more about JSON here

What we do with Our JSON.

In this example we will download and parse json data. To download we will use HttpURLConnection as well as AsyncTask. Then to parse we will use the JSONObject and JSONArray classes.

What is HttpUrlConnection?

HttpUrlconnection is a UrlConnection for HTTP used to send as well receive data over the web. These data may be of any type and length.

This is the class that enables us make HTTP calls over the web from our android app. In this case our HTTP calls will result in us downloading a blob of JSON string from online. Then we parse that JSON data.

Learn more about HttpURLConnection here.

AsyncTask?

AsyncTask is a helper class for performing easy threading and created around Thread.

AsyncTask will allow us to create smoothly working applications even though we are doing a time-consuming task like downloading data from online. This is because we will offload that task to the background thread via AsyncTask.

Learn more about AsyncTask here.

What is ListView?

A gridview is an adapterview that shows items in a scrollabe list.

Once we've parsed our data we will bind them to a ListView

Learn more about ListView here.

Examples We Look At.

Well we look at three examples:

  1. Android JSON - Simple ListView - Download,Parse and Show
  2. Android JSON - ListView Multiple Fields - Download,Parse then Show
  3. Android JSON - ListView Master Detail - Download,Parse,Show

1. Android JSON - Simple ListView - Download,Parse and Show

Android Native JSON - Simple ListView - Download,Parse and Show tutorial.

Here's the project demo:

Java Classes

(a). Our Connector Class
  • Establish connection for us.
  • Set connection properties.
package com.tutorials.hp.jsonlistview.m_JSON;

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

public class Connector {

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

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

            return con;

        } catch (MalformedURLException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        }
    }

}
(b). Our JSON Downloader Class
  • Where we download our json data from network.
  • We do this in background thread using AsyncTask.
  • Meanwhile we show a progress dialog.
  • After this, we pass our json data to JSONParser class to be parsed.
package com.tutorials.hp.jsonlistview.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListView;
import android.widget.Toast;

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

public class JSONDownloader extends AsyncTask<Void,Void,String> {

    Context c;
    String jsonURL;
    ListView lv;

    ProgressDialog pd;

    public JSONDownloader(Context c, String jsonURL, ListView lv) {
        this.c = c;
        this.jsonURL = jsonURL;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd=new ProgressDialog(c);
        pd.setTitle("Download JSON");
        pd.setMessage("Downloading...Please wait");
        pd.show();
    }

    @Override
    protected String doInBackground(Void... voids) {
        return this.download();
    }

    @Override
    protected void onPostExecute(String jsonData) {
        super.onPostExecute(jsonData);

        pd.dismiss();
        if(jsonData.startsWith("Error"))
        {
            Toast.makeText(c, jsonData, Toast.LENGTH_SHORT).show();
        }else {
            //PARSE
            new JSONParser(c,jsonData, lv).execute();

        }

    }
    private String download()
    {
        Object connection=Connector.connect(jsonURL);
        if(connection.toString().startsWith("Error"))
        {
            return connection.toString();
        }

        try
        {
            //ESTABLISH CONNECTION
            HttpURLConnection con= (HttpURLConnection) connection;
            if(con.getResponseCode()==con.HTTP_OK)
            {
                //GET INPUT FROM STREAM
                InputStream is=new BufferedInputStream(con.getInputStream());
                BufferedReader br=new BufferedReader(new InputStreamReader(is));

                String line;
                StringBuffer jsonData=new StringBuffer();

                //READ
                while ((line=br.readLine()) != null)
                {
                    jsonData.append(line+"n");
                }

                //CLOSE RESOURCES
                br.close();
                is.close();

                //RETURN JSON
                return jsonData.toString();

            }else
            {
                return "Error "+con.getResponseMessage();
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();
        }
    }
}
(c). Our JSON Parser Class
  • Receives the JSON string we downloaded.
  • So we parse this particular json,filling an arraylist.
  • Then we bind our arraylist of data our view component via an adapter.
package com.tutorials.hp.jsonlistview.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;

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

    Context c;
    String jsonData;
    ListView lv;

    ProgressDialog pd;
    ArrayList<String> users=new ArrayList<>();

    public JSONParser(Context c, String jsonData, ListView lv) {
        this.c = c;
        this.jsonData = jsonData;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd=new ProgressDialog(c);
        pd.setTitle("Parse JSON");
        pd.setMessage("Parsing...Please wait");
        pd.show();
    }

    @Override
    protected Boolean doInBackground(Void... voids) {
        return this.parse();
    }

    @Override
    protected void onPostExecute(Boolean isParsed) {
        super.onPostExecute(isParsed);

        pd.dismiss();
        if(isParsed)
        {
            //BIND
            ArrayAdapter<String> adapter=new ArrayAdapter<String>(c,android.R.layout.simple_list_item_1,users);
            lv.setAdapter(adapter);

            lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                    Toast.makeText(c, users.get(i), Toast.LENGTH_SHORT).show();
                }
            });

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

    }

    private Boolean parse()
    {
        try
        {
            JSONArray ja=new JSONArray(jsonData);
            JSONObject jo;

            users.clear();
            for (int i=0;i<ja.length();i++)
            {
                jo=ja.getJSONObject(i);

                String name=jo.getString("name");
                users.add(name);
            }

            return true;

        } catch (JSONException e) {
            e.printStackTrace();
            return false;
        }
    }
}
(d). Our MainActivity Class
  • Our launcher activity.
  • We start our downloader, passing in URL as well as other parameters.
package com.tutorials.hp.jsonlistview;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ListView;

import com.tutorials.hp.jsonlistview.m_JSON.JSONDownloader;

public class MainActivity extends AppCompatActivity {

    String jsonURL="http://jsonplaceholder.typicode.com/users";
    ListView lv;

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

        lv= (ListView) findViewById(R.id.lv);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new JSONDownloader(MainActivity.this,jsonURL,lv).execute();
            }
        });
    }
}

Our Layout

(a). activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.tutorials.hp.jsonlistview.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>
(b). content_main.xml
  • Displays our view
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    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.jsonlistview.MainActivity"
    tools:showIn="@layout/activity_main">

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
         />
</RelativeLayout>

Section 6 : Our Manifest

  • Make sure you add permission for accessing internet.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.tutorials.hp.jsonlistview">

    <uses-permission android:name="android.permission.INTERNET"/>
    ...

</manifest>

Download

You can download the full project here.

No. Resource Direct Links
1. GitHub Source Code Browse
2. Source Code Download
3. YouTube Channel
4. YouTube Video Tutorial

2. Android Native JSON - ListView Multiple Fields - Download,Parse then Show

Android Native JSON - ListView Multiple Fields - Download,Parse then Show Tutorial.

Java Code

(a). Our Connector Class
  • Establish connection for us.
  • Set connection properties.
package com.tutorials.hp.jsonlistviewmulti_items.m_JSON;

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

/*
 * -------------------ROLES-----------------------
 * 1.SET CONNECTION PROPRTIES
 * 2.ESTABLISH AND RETURN CONNECTION OBJ
 */
public class Connector {

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

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

            return con;

        } catch (MalformedURLException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        }
    }

}
(b). Our JSON Downloader Class
  • Where we download our json data from network.
  • We do this in background thread using AsyncTask.
  • Meanwhile we show a progress dialog.
  • After this, we pass our json data to JSONParser class to be parsed.
package com.tutorials.hp.jsonlistviewmulti_items.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListView;

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

/*
 * -----------------------ROLES-------------------------
 * 1.CONNECT TO NETWORK
 * 2.DOWNLOAD DATA IN BACKGROUND THREAD
 * 3.SEND THE DATA TO PARSER TO BE PARSED
 */
public class JSONDownloader extends AsyncTask<Void,Void,String> {

    Context c;
    String jsonURL;
    ListView lv;

    ProgressDialog pd;

    public JSONDownloader(Context c, String jsonURL, ListView lv) {
        this.c = c;
        this.jsonURL = jsonURL;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd=new ProgressDialog(c);
        pd.setTitle("Download JSON");
        pd.setMessage("Downloading...Please wait");
        pd.show();

    }

    @Override
    protected String doInBackground(Void... voids) {
        return downlaod();
    }

    @Override
    protected void onPostExecute(String jsonData) {
        super.onPostExecute(jsonData);

        pd.dismiss();
        if(jsonData.startsWith("Error"))
        {
            String error=jsonData;
        }else
        {
            //PARSE
            new JSONParser(c,jsonData,lv).execute();
        }

    }

    private String downlaod()
    {
        Object connection=Connector.connect(jsonURL);
        if(connection.toString().startsWith("Error"))
        {
            return connection.toString();
        }

        //DOWNLOAD
        try
        {
            HttpURLConnection con= (HttpURLConnection) connection;
            if(con.getResponseCode()==con.HTTP_OK)
            {
                //GET INPUT FROM STREAM
                InputStream is=new BufferedInputStream(con.getInputStream());
                BufferedReader br=new BufferedReader(new InputStreamReader(is));

                String line;
                StringBuffer jsonData=new StringBuffer();

                //READ
                while ((line=br.readLine()) != null)
                {
                    jsonData.append(line+"n");
                }

                //CLOSE RESOURCES
                br.close();
                is.close();

                //RETURN JSON
                return jsonData.toString();

            }else
            {
                return "Error "+con.getResponseMessage();
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();
        }
    }

}
(c). Our JSON Parser Class
  • Receives the JSON string we downloaded.
  • So we parse this particular json,filling an arraylist.
  • Then we bind our arraylist of data our view component via an adapter.
package com.tutorials.hp.jsonlistviewmulti_items.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListView;
import android.widget.Toast;

import com.tutorials.hp.jsonlistviewmulti_items.m_Model.User;
import com.tutorials.hp.jsonlistviewmulti_items.m_UI.CustomAdapter;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;

/*
 * -----------------    ROLES -----------------------
 * 1.RECEIVE DOWNLOADED DATA
 * 2.PARSE IT
 * 3.CALL ADAPTER CLASS TO BIND IT TO CUSTOM GRIDVIEW
 */
public class JSONParser extends AsyncTask<Void,Void,Boolean>{

    Context c;
    String jsonData;
    ListView lv;

    ProgressDialog pd;
    ArrayList<User> users=new ArrayList<>();

    public JSONParser(Context c, String jsonData, ListView lv) {
        this.c = c;
        this.jsonData = jsonData;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd=new ProgressDialog(c);
        pd.setTitle("Parse JSON");
        pd.setMessage("Parsing...Please wait");
        pd.show();
    }

    @Override
    protected Boolean doInBackground(Void... voids) {
        return parse();
    }

    @Override
    protected void onPostExecute(Boolean isParsed) {
        super.onPostExecute(isParsed);

        pd.dismiss();
        if(isParsed)
        {
            //BIND
            lv.setAdapter(new CustomAdapter(c,users));
        }else
        {
            Toast.makeText(c, "Unable To Parse,Check Your Log output", Toast.LENGTH_SHORT).show();
        }

   }

    private Boolean parse()
    {
        try
        {
            JSONArray ja=new JSONArray(jsonData);
            JSONObject jo;

            users.clear();
            User user;

            for (int i=0;i<ja.length();i++)
            {
                jo=ja.getJSONObject(i);

                String name=jo.getString("name");
                String username=jo.getString("username");
                String email=jo.getString("email");

                user=new User();

                user.setName(name);
                user.setUsername(username);
                user.setEmail(email);

                users.add(user);
            }

            return true;

        } catch (JSONException e) {
            e.printStackTrace();
            return false;
        }
    }

}
(d). Our CustomAdapter Class
  • Inflate our Custom Model into a View Item for our ListView.
  • Bind data to our AdapterView.
package com.tutorials.hp.jsonlistviewmulti_items.m_UI;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.tutorials.hp.jsonlistviewmulti_items.R;
import com.tutorials.hp.jsonlistviewmulti_items.m_Model.User;

import java.util.ArrayList;

/*
 * ---------------------------ROLES-------------------------------
 * | 1.INFLATE MODEL LAYOUT
 * | 2.BIND DATA TO GRIDVIEW
 * ----------------------------------------------------------------
 */
public class CustomAdapter extends BaseAdapter{

    Context c;
    ArrayList<User> users;

    public CustomAdapter(Context c, ArrayList<User> users) {
        this.c = c;
        this.users = users;
    }

    @Override
    public int getCount() {
        return users.size();
    }

    @Override
    public Object getItem(int i) {
        return users.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        if(view==null)
        {
            view=LayoutInflater.from(c).inflate(R.layout.model,viewGroup,false);
        }

        TextView nameTxt= (TextView) view.findViewById(R.id.nameTxt);
        TextView usernameTxt= (TextView) view.findViewById(R.id.usernameTxt);
        TextView emailTxt= (TextView) view.findViewById(R.id.emailTxt);

        User user= (User) this.getItem(i);

        nameTxt.setText(user.getName());
        emailTxt.setText(user.getEmail());
        usernameTxt.setText(user.getUsername());

        return view;
    }
}
(e). Our MainActivity Class
  • Our launcher activity.
  • We start our downloader, passing in URL as well as other parameters.
package com.tutorials.hp.jsonlistviewmulti_items;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ListView;

import com.tutorials.hp.jsonlistviewmulti_items.m_JSON.JSONDownloader;

public class MainActivity extends AppCompatActivity {

    String jsonURL="http://jsonplaceholder.typicode.com/users";
    ListView lv;

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

        lv = (ListView) findViewById(R.id.lv);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new JSONDownloader(MainActivity.this,jsonURL, lv).execute();
            }
        });
    }

}

Our Layouts

(a). activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.tutorials.hp.jsonlistviewmulti_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>
(b). content_main.xml
  • Displays our adapter view
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    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.jsonlistviewmulti_items.MainActivity"
    tools:showIn="@layout/activity_main">

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
         />
</RelativeLayout>
(c). model.xml
  • Inflated into a single viewitem for our ListView.
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    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="Name"
                android:id="@+id/nameTxt"
                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="Email....................."
                android:lines="3"
                android:id="@+id/emailTxt"
                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="Username"
                android:textStyle="italic"
                android:id="@+id/usernameTxt" />

    </LinearLayout>

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

Our Manifest

  • Make sure you add permission for accessing internet.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.tutorials.hp.jsonlistviewmulti_items">

    <uses-permission android:name="android.permission.INTERNET"/>
    ...

</manifest>

Download

You can download the full project here.

No. Resource Direct Links
1. GitHub Source Code Browse
2. Source Code Download
3. YouTube Channel

3. Android Native JSON - ListView Master Detail - Download,Parse,Show

Here in this tutorial,we talk JSON and ListView.We download JSON data from online here : http://jsonplaceholder.typicode.com/.

This json data we parse natively using org.json classes : JSONArray and JSONObject,no third party library.We then bind this data to our Custom ListView.This,our MainActivity, acts as our Master View. When a ListView item is clicked, we open detail activity passing data.

Here's the demo:

AndroidManifest.xml

Make sure to add permission for internet connectivity.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.tutorials.hp.jsonlistviewmdetail">

    <uses-permission android:name="android.permission.INTERNET" />
    ...

</manifest>

Java Code

(a). Our Model Class
package com.tutorials.hp.jsonlistviewmdetail.m_Model;

public class User {

    String username,name,email;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}
(b). Our Connector Class
package com.tutorials.hp.jsonlistviewmdetail.m_JSON;

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

/**
 * -------------------ROLES-----------------------
 * 1.SET CONNECTION PROPRTIES
 * 2.ESTABLISH AND RETURN CONNECTION OBJ
 */
public class Connector {

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

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

            return con;

        } catch (MalformedURLException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        }
    }

}
(c). JSON Downloader Class
package com.tutorials.hp.jsonlistviewmdetail.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.GridView;
import android.widget.ListView;
import android.widget.Toast;

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

/**
 * -----------------------ROLES-------------------------
 * 1.CONNECT TO NETWORK
 * 2.DOWNLOAD DATA IN BACKGROUND THREAD
 * 3.SEND THE DATA TO PARSER TO BE PARSED
 */
public class JSONDownloader extends AsyncTask<Void,Void,String> {

    Context c;
    String jsonURL;
    ListView lv;

    ProgressDialog pd;

    public JSONDownloader(Context c, String jsonURL, ListView lv) {
        this.c = c;
        this.jsonURL = jsonURL;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd=new ProgressDialog(c);
        pd.setTitle("Download JSON");
        pd.setMessage("Downloading...Please wait");
        pd.show();

    }

    @Override
    protected String doInBackground(Void... voids) {
        return download();
    }

    @Override
    protected void onPostExecute(String jsonData) {
        super.onPostExecute(jsonData);

        pd.dismiss();

        if(jsonData.startsWith("Error"))
        {
            String error=jsonData;
            Toast.makeText(c, error, Toast.LENGTH_SHORT).show();
        }else
        {
            //PARSER
            new JSONParser(c,jsonData, lv).execute();
        }

    }

    //DOWNLOAD
    private String download()
    {
        Object connection=Connector.connect(jsonURL);
        if(connection.toString().startsWith("Error"))
        {
            return connection.toString();
        }

        try
        {
            HttpURLConnection con= (HttpURLConnection) connection;
            if(con.getResponseCode()==con.HTTP_OK)
            {
                //GET INPUT FROM STREAM
                InputStream is=new BufferedInputStream(con.getInputStream());
                BufferedReader br=new BufferedReader(new InputStreamReader(is));

                String line;
                StringBuffer jsonData=new StringBuffer();

                //READ
                while ((line=br.readLine()) != null)
                {
                    jsonData.append(line+"n");
                }

                //CLOSE RESOURCES
                br.close();
                is.close();

                //RETURN JSON
                return jsonData.toString();

            }else
            {
                return "Error "+con.getResponseMessage();
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "Error "+e.getMessage();

        }

    }

}
(d). JSON Parser Class
package com.tutorials.hp.jsonlistviewmdetail.m_JSON;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.GridView;
import android.widget.ListView;
import android.widget.Toast;

import com.tutorials.hp.jsonlistviewmdetail.m_Model.User;
import com.tutorials.hp.jsonlistviewmdetail.m_UI.CustomAdapter;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;

/**
 * -----------------    ROLES -----------------------
 * 1.RECEIVE DOWNLOADED DATA
 * 2.PARSE IT
 * 3.CALL ADAPTER CLASS TO BIND IT TO CUSTOM gridview
 */
public class JSONParser extends AsyncTask<Void,Void,Boolean>{

    Context c;
    String jsonData;
    ListView lv;

    ProgressDialog pd;
    ArrayList<User> users=new ArrayList<>();

    public JSONParser(Context c, String jsonData, ListView lv) {
        this.c = c;
        this.jsonData = jsonData;
        this.lv = lv;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd=new ProgressDialog(c);
        pd.setTitle("Parse");
        pd.setMessage("Parsing...Please wait");
        pd.show();
    }

    @Override
    protected Boolean doInBackground(Void... voids) {
        return parse();
    }

    @Override
    protected void onPostExecute(Boolean isParsed) {
        super.onPostExecute(isParsed);

        pd.dismiss();
        if(isParsed)
        {
            //BIND
            lv.setAdapter(new CustomAdapter(c,users));
        }else
        {
            Toast.makeText(c, "Unable To Parse,Check Your Log output", Toast.LENGTH_SHORT).show();
        }

    }

    private Boolean parse()
    {
        try
        {
            JSONArray ja=new JSONArray(jsonData);
            JSONObject jo;

            users.clear();
            User user;

            for (int i=0;i<ja.length();i++)
            {
                jo=ja.getJSONObject(i);

                String name=jo.getString("name");
                String username=jo.getString("username");
                String email=jo.getString("email");

                user=new User();

                user.setName(name);
                user.setUsername(username);
                user.setEmail(email);

                users.add(user);
            }

            return true;

        } catch (JSONException e) {
            e.printStackTrace();
            return false;
        }
    }
}
(e). CustomAdapter Class
package com.tutorials.hp.jsonlistviewmdetail.m_UI;

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.tutorials.hp.jsonlistviewmdetail.DetailActivity;
import com.tutorials.hp.jsonlistviewmdetail.R;
import com.tutorials.hp.jsonlistviewmdetail.m_Model.User;

import java.util.ArrayList;

public class CustomAdapter  extends BaseAdapter{

    Context c;
    ArrayList<User> users;

    public CustomAdapter(Context c, ArrayList<User> users) {
        this.c = c;
        this.users = users;
    }

    @Override
    public int getCount() {
        return users.size();
    }

    @Override
    public Object getItem(int i) {
        return users.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {

        if(view==null)
        {
            view=LayoutInflater.from(c).inflate(R.layout.model,viewGroup,false);
        }

        TextView nameTxt= (TextView) view.findViewById(R.id.nameTxt);
        TextView emailTxt= (TextView) view.findViewById(R.id.emailTxt);
        TextView usernameTxt= (TextView) view.findViewById(R.id.usernameTxt);

        User user= (User) this.getItem(i);

        final String name=user.getName();
        final String email=user.getEmail();
        final String username=user.getUsername();

        nameTxt.setText(name);
        emailTxt.setText(email);
        usernameTxt.setText(username);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //OPEN DETAIL ACTIVITY
               openDetailActivity(name,email,username);

            }
        });
        return view;
    }
    ////open activity
    private void openDetailActivity(String...details)
    {
        Intent i=new Intent(c,DetailActivity.class);
        i.putExtra("NAME_KEY",details[0]);
        i.putExtra("EMAIL_KEY",details[1]);
        i.putExtra("USERNAME_KEY",details[2]);

        c.startActivity(i);

    }

}
(f). Detail Activity Class
package com.tutorials.hp.jsonlistviewmdetail;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

public class DetailActivity extends AppCompatActivity {

    TextView nameTxt,emailTxt, usernameTxt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        nameTxt = (TextView) findViewById(R.id.nameDetailTxt);
        emailTxt= (TextView) findViewById(R.id.emailDetailTxt);
        usernameTxt = (TextView) findViewById(R.id.usernameDetailTxt);

        //GET INTENT
        Intent i=this.getIntent();

        //RECEIVE DATA
        String name=i.getExtras().getString("NAME_KEY");
        String email=i.getExtras().getString("EMAIL_KEY");
        String username=i.getExtras().getString("USERNAME_KEY");

        //BIND DATA
        nameTxt.setText(name);
        emailTxt.setText(email);
        usernameTxt.setText(username);
    }
}
(g). MainActivity Class
package com.tutorials.hp.jsonlistviewmdetail;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ListView;

import com.tutorials.hp.jsonlistviewmdetail.m_JSON.JSONDownloader;

public class MainActivity extends AppCompatActivity {

    String jsonURL="http://jsonplaceholder.typicode.com/users";
    ListView lv;

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

        lv = (ListView) findViewById(R.id.lv);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new JSONDownloader(MainActivity.this,jsonURL, lv).execute();

            }
        });
    }
}

Layouts

(a). activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.tutorials.hp.jsonlistviewmulti_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>
(b). content_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    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.jsonlistviewmdetail.MainActivity"
    tools:showIn="@layout/activity_main">

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
         />
</RelativeLayout>
(c). model.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    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="Name"
                android:id="@+id/nameTxt"
                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="Email....................."
                android:lines="3"
                android:id="@+id/emailTxt"
                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="Username"
                android:textStyle="italic"
                android:id="@+id/usernameTxt" />
    </LinearLayout>
</android.support.v7.widget.CardView>
(d). activity_detail.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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"
    tools:context="com.tutorials.hp.jsonlistviewmdetail.DetailActivity">

    <android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal" android:layout_width="match_parent"
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:layout_margin="5dp"
        card_view:cardCornerRadius="10dp"
        card_view:cardElevation="5dp"

        android:layout_height="match_parent">

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:weightSum="1">

            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <ImageView
                    android:id="@+id/articleDetailImg"
                    android:layout_width="160dp"
                    android:layout_height="wrap_content"
                    android:paddingLeft="10dp"
                    android:paddingRight="10dp"
                    android:layout_alignParentTop="true"
                    android:scaleType="centerCrop"
                    android:src="@drawable/user" />

                <LinearLayout
                    android:orientation="vertical"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:id="@+id/nameDetailTxt"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textAppearance="?android:attr/textAppearanceLarge"
                        android:padding="5dp"
                        android:minLines="1"
                        android:textStyle="bold"
                        android:textColor="@color/colorAccent"
                        android:text="Title" />
                    <TextView
                        android:id="@+id/usernameDetailTxt"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textAppearance="?android:attr/textAppearanceLarge"
                        android:padding="5dp"
                        android:minLines="1"
                        android:textStyle="bold"
                        android:text="Username" />
                </LinearLayout>

            </LinearLayout>

            <LinearLayout
                android:layout_width="fill_parent"
                android:layout_height="match_parent"
                android:layout_marginTop="?attr/actionBarSize"
                android:orientation="vertical"
                android:paddingLeft="5dp"
                android:paddingRight="5dp"
                android:paddingTop="5dp">

                <TextView
                    android:id="@+id/emailDetailTxt"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textAppearance="?android:attr/textAppearanceLarge"
                    android:padding="5dp"
                    android:textColor="@color/colorAccent"
                    android:text="DATE" />
                <TextView
                    android:id="@+id/descDetailTxt"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textAppearance="?android:attr/textAppearanceLarge"
                    android:padding="5dp"
                    android:textColor="#0f0f0f"
                    android:minLines="4"
                    android:text="This user has worked with our company for two years now.He has been dedicated and really a team player.The tasks we have assigned him have been executed expertly.He is a true professional..." />

                <TextView
                    android:id="@+id/linkDetailTxt"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textAppearance="?android:attr/textAppearanceMedium"
                    android:padding="5dp"
                    android:textColor="@color/colorPrimaryDark"
                    android:textStyle="italic"
                    android:text="Link" />

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

Download

You can download the full project here.

No. Resource Direct Links
1. GitHub Source Code Browse
2. Source Code Download
3. YouTube Channel

How do You Feel after reading this?

According to scientists, we humans have 8 primary innate emotions: joy, acceptance, fear, surprise, sadness, disgust, anger, and anticipation. Feel free to tell us how you feel about this article using these emotes or via the comment section. This feedback helps us gauge our progress.

Help me Grow.

I set myself some growth ambitions I desire to achieve by this year's end regarding this website and my youtube channel. Am halfway. Help me reach them by:




Recommendations


What do You Think


Previous Post Next Post