ตัวอย่างการทำ ListView อ่านข้อมูล JSON ด้วย GSon

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{
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status: "ok",
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count: 10,
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count_total: 1732,
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pages: 174,
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    posts: [
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        {
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            id: 23479,
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            url: "http://blog.teamtreehouse.com/voodoo-responsive-tables-javascript-graphs-treehouse-show-episode-90",
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            title: "Voodoo, Responsive Tables, JavaScript Graphs | The Treehouse Show Episode 90",
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            date: "2014-05-13 18:02:54",
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            author: "Jason Seifer",
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            thumbnail: null
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        },
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        {
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            id: 23432,
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            url: "http://blog.teamtreehouse.com/working-home-3-tips-staying-task",
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            title: "Working from Home? 3 Tips to Staying on Task",
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            date: "2014-05-13 08:00:05",
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            author: "Theresa Cramer",
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            thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/05/Computer-Desk-David-Martyn-Hunt-Flick-150x150.jpg"
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        },
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            ....
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    ]
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}

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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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    android:layout_width="match_parent"
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    android:layout_height="match_parent">
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    <ListView
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        android:layout_width="match_parent"
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        android:layout_height="match_parent"
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        android:id="@+id/listView" />
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</RelativeLayout>

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public static final String URL =
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        "http://blog.teamtreehouse.com/api/get_recent_summary/";

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private class SimpleTask extends AsyncTask<String, Void, String> {
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    @Override
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    protected void onPreExecute() {
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        // Create Show ProgressBar
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    }
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    protected String doInBackground(String... urls)   {
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        String result = "";
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        try {
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            HttpGet httpGet = new HttpGet(urls[0]);
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            HttpClient client = new DefaultHttpClient();
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            HttpResponse response = client.execute(httpGet);
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            int statusCode = response.getStatusLine().getStatusCode();
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            if (statusCode == 200) {
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                InputStream inputStream = response.getEntity().getContent();
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                BufferedReader reader = new BufferedReader
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                        (new InputStreamReader(inputStream));
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                String line;
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                while ((line = reader.readLine()) != null) {
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                    result += line;
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                }
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            }
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        } catch (ClientProtocolException e) {
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        } catch (IOException e) {
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        }
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        return result;
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    }
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    protected void onPostExecute(String jsonString)  {
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        // Dismiss ProgressBar
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        showData(jsonString);
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    }
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}

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new SimpleTask().execute(URL);

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private void showData(String jsonString) {
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    Toast.makeText(this, jsonString, Toast.LENGTH_LONG).show();
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}

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

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package com.devahoy.sample.ahoygson;
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import android.os.AsyncTask;
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import android.os.Bundle;
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import android.support.v7.app.ActionBarActivity;
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import android.widget.Toast;
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import org.apache.http.HttpResponse;
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import org.apache.http.client.ClientProtocolException;
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import org.apache.http.client.HttpClient;
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import org.apache.http.client.methods.HttpGet;
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import org.apache.http.impl.client.DefaultHttpClient;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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public class MainActivity extends ActionBarActivity {
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    public static final String URL =
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            "http://blog.teamtreehouse.com/api/get_recent_summary/";
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    @Override
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    protected void onCreate(Bundle savedInstanceState) {
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        super.onCreate(savedInstanceState);
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        setContentView(R.layout.activity_main);
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        new SimpleTask().execute(URL);
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    }
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    private class SimpleTask extends AsyncTask<String, Void, String> {
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        @Override
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        protected void onPreExecute() {
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            // Create Show ProgressBar
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        }
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        protected String doInBackground(String... urls)   {
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            String result = "";
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            try {
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                HttpGet httpGet = new HttpGet(urls[0]);
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                HttpClient client = new DefaultHttpClient();
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                HttpResponse response = client.execute(httpGet);
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                int statusCode = response.getStatusLine().getStatusCode();
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                if (statusCode == 200) {
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                    InputStream inputStream = response.getEntity().getContent();
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                    BufferedReader reader = new BufferedReader
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                            (new InputStreamReader(inputStream));
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                    String line;
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                    while ((line = reader.readLine()) != null) {
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                        result += line;
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                    }
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                }
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            } catch (ClientProtocolException e) {
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            } catch (IOException e) {
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            }
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            return result;
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        }
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        protected void onPostExecute(String jsonString)  {
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            // Dismiss ProgressBar
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            showData(jsonString);
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        }
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    }
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    private void showData(String jsonString) {
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        Toast.makeText(this, jsonString, Toast.LENGTH_LONG).show();
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    }

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apply plugin: 'android'
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android {
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    ...
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}
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dependencies {
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    ...
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    compile 'com.google.code.gson:gson:2.2.4'
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}

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import com.google.gson.Gson;

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{
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  status: "ok",
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  count: 10,
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  count_total: 1900,
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  pages: 190,
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  posts: [
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    {
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      id: 24453,
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      url: "http://blog.teamtreehouse.com/havent-started-programming-yet",
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      title: "The Real Reason Why Everyone Should Learn to Code",
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      date: "2014-11-20 08:30:48",
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      author: "Dave McFarland",
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      thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/11/Screen-Shot-2014-11-18-at-11.15.00-AM-150x150.png"
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    },
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    {
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      id: 24462,
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      url: "http://blog.teamtreehouse.com/css-shapes",
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      title: "CSS Shapes",
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      date: "2014-11-19 12:13:20",
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      author: "Jason Seifer",
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      thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/11/Getting-Started-with-CSS-Shapes-Wrapping-content-around-custom-paths-HTML5-Rocks-2014-11-19-12-11-51-150x150.jpg"
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    },
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    ...
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  ]
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}

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public class Post {
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    int id;
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    String url;
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    String title;
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    String date;
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    String author;
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    String thumbnail;
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// Getter and Setter
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}

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public class Blog {
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    String status;
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    int count;
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    @SerializedName("count_total")
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    int totalCount;
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    int pages;
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    List<Post> posts;
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    // Getter and Setter
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}

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private void showData(String jsonString) {
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    Gson gson = new Gson();
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    Blog blog = gson.fromJson(jsonString, Blog.class);
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    StringBuilder builder = new StringBuilder();
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    builder.setLength(0);
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    List<Post> posts = blog.getPosts();
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    for (Post post : posts) {
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        builder.append(post.getTitle());
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        builder.append("\n\n");
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    }
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    Toast.makeText(this, builder.toString(), Toast.LENGTH_LONG).show();
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}

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<?xml version="1.0" encoding="utf-8"?>
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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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                android:layout_width="match_parent"
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                android:layout_height="match_parent">
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    <ImageView
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        android:layout_width="64dp"
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        android:layout_height="64dp"
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        android:layout_marginRight="8dp"
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        android:id="@+id/post_thumbnail"
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        android:src="@drawable/ic_launcher"
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        android:layout_alignParentTop="true"
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        android:layout_alignParentLeft="true"
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        android:layout_alignParentStart="true"/>
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    <TextView
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        android:layout_width="wrap_content"
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        android:layout_height="wrap_content"
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        android:text="Title"
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        android:textSize="16sp"
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        android:textStyle="bold"
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        android:layout_marginTop="8dp"
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        android:id="@+id/post_title"
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        android:layout_alignParentTop="true"
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        android:layout_toRightOf="@+id/post_thumbnail"/>
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    <TextView
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        android:layout_width="wrap_content"
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        android:layout_height="wrap_content"
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        android:text="Author Name"
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        android:id="@+id/post_author"
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        android:layout_marginTop="8dp"
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        android:layout_below="@+id/post_title"
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        android:layout_alignLeft="@+id/post_title"
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        android:layout_alignStart="@+id/post_title"/>
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    <TextView android:layout_width="wrap_content"
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              android:layout_height="wrap_content"
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              android:text="Date"
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              android:id="@+id/post_date"
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              android:layout_marginRight="8dp"
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              android:layout_alignTop="@+id/post_author"
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              android:layout_alignParentRight="true"
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              android:layout_alignParentEnd="true"/>
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</RelativeLayout>

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package com.devahoy.sample.ahoygson;
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import android.view.View;
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import android.view.ViewGroup;
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import android.widget.BaseAdapter;
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public class CustomAdapter extends BaseAdapter {
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    @Override
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    public int getCount() {
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        return 0;
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    }
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    @Override
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    public Object getItem(int position) {
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        return null;
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    }
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    @Override
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    public long getItemId(int position) {
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        return 0;
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    }
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    @Override
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    public View getView(int position, View convertView, ViewGroup parent) {
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        return null;
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    }
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}

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public class CustomAdapter extends BaseAdapter {
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    private LayoutInflater mInflater;
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    List<Post> mPosts;
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    public CustomAdapter(Activity activity, List<Post> posts) {
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        mInflater = (LayoutInflater) activity.getSystemService(
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                Context.LAYOUT_INFLATER_SERVICE);
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        mPosts = posts;
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    }
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    ...
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}

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@Override
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public int getCount() {
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    return mPosts.size();
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}
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@Override
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public Object getItem(int position) {
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    return mPosts.get(position);
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}
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@Override
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public long getItemId(int position) {
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    return position;
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}

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private static class ViewHolder {
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    ImageView thumbnail;
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    TextView title;
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    TextView author;
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    TextView date;
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}

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@Override
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public View getView(int position, View convertView, ViewGroup parent) {
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    if (convertView == null) {
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        convertView = mInflater.inflate(R.layout.post, parent, false);
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        mViewHolder = new ViewHolder();
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        mViewHolder.thumbnail = (ImageView) convertView.findViewById(R.id.post_thumbnail);
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        mViewHolder.author = (TextView) convertView.findViewById(R.id.post_author);
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        mViewHolder.title = (TextView) convertView.findViewById(R.id.post_title);
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        mViewHolder.date = (TextView) convertView.findViewById(R.id.post_date);
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        convertView.setTag(mViewHolder);
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    } else {
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        mViewHolder = (ViewHolder) convertView.getTag();
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    }
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    return convertView;
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}

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private ViewHolder mViewHolder;

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public class MainActivity extends ActionBarActivity {
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    public static final String URL =
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            "http://blog.teamtreehouse.com/api/get_recent_summary/";
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    private ListView mListView;
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    private CustomAdapter mAdapter;
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    ...
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}

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@Override
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protected void onCreate(Bundle savedInstanceState) {
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    super.onCreate(savedInstanceState);
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    setContentView(R.layout.activity_main);
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    mListView = (ListView) findViewById(R.id.listView);
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    new SimpleTask().execute(URL);
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}

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private void showData(String jsonString) {
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    Gson gson = new Gson();
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    Blog blog = gson.fromJson(jsonString, Blog.class);
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    List<Post> posts = blog.getPosts();
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    mAdapter = new CustomAdapter(this, posts);
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    mListView.setAdapter(mAdapter);
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}

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Post post = mPosts.get(position);
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mViewHolder.author.setText(post.getAuthor());
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mViewHolder.title.setText(post.title);
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mViewHolder.date.setText(post.date);

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public class CustomAdapter extends BaseAdapter {
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    private LayoutInflater mInflater;
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    private List<Post> mPosts;
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    private ViewHolder mViewHolder;
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    private Bitmap mBitmap;
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    private Post mPost
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    ....
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    ....
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    @Override
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    public View getView(int position, View convertView, ViewGroup parent) {
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        ...
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        if (mPost.getThumbnail() != null) {
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                new AsyncTask<Void, Void, Void>() {
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                    @Override
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                    protected Void doInBackground(Void... params) {
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                        try {
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                            URL url = new URL(mPost.getThumbnail());
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                            mBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
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                        } catch (MalformedURLException e) {
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                        } catch (IOException e) {
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                        }
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                        return null;
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                    }
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                }.execute();
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            mViewHolder.thumbnail.setImageBitmap(mBitmap);
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            ...
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            ...
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    }
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}

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@Override
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    public View getView(int position, View convertView, ViewGroup parent) {
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        if (convertView == null) {
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            convertView = mInflater.inflate(R.layout.post, parent, false);
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            mViewHolder = new ViewHolder();
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            mViewHolder.thumbnail = (ImageView) convertView.findViewById(R.id.post_thumbnail);
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            mViewHolder.author = (TextView) convertView.findViewById(R.id.post_author);
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            mViewHolder.title = (TextView) convertView.findViewById(R.id.post_title);
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            mViewHolder.date = (TextView) convertView.findViewById(R.id.post_date);
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            convertView.setTag(mViewHolder);
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        } else {
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            mViewHolder = (ViewHolder) convertView.getTag();
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        }
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        mPost = mPosts.get(position);
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        if (mPost.getThumbnail() != null) {
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            new AsyncTask<Void, Void, Void>() {
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                @Override
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                protected Void doInBackground(Void... params) {
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                    try {
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                        URL url = new URL(mPost.getThumbnail());
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                        mBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
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                    } catch (MalformedURLException e) {
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                    } catch (IOException e) {
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                    }
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                    return null;
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                }
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            }.execute();
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            mViewHolder.thumbnail.setImageBitmap(mBitmap);
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        }
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        mViewHolder.author.setText(mPost.getAuthor());
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        mViewHolder.title.setText(mPost.title);
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        mViewHolder.date.setText(mPost.date);
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        return convertView;
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    }