Android GSON with Custom ListView Tutorial , Article Link: http://devahoy.com/2014/05/android-custom-listview-with-gson-tutorial/

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_margin="10dp"
        android:dividerHeight="2dp"
        android:id="@+id/listView" />

</RelativeLayout>

AndroidManifest.xml

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

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

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.devahoy.sample.ahoygson.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

Blog.java

package com.devahoy.sample.ahoygson;

import com.google.gson.annotations.SerializedName;

import java.util.List;

public class Blog {
    String status;

    int count;

    @SerializedName("count_total")
    int totalCount;

    int pages;

    List<Post> posts;

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public int getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(int totalCount) {
        this.totalCount = totalCount;
    }

    public int getPages() {
        return pages;
    }

    public void setPages(int pages) {
        this.pages = pages;
    }

    public List<Post> getPosts() {
        return posts;
    }

    public void setPosts(List<Post> posts) {
        this.posts = posts;
    }
}

build.gradle

apply plugin: 'android'

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.3"

    defaultConfig {
        minSdkVersion 10
        targetSdkVersion 18
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            runProguard false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:19.+'
    compile 'com.google.code.gson:gson:2.2.4'
}

CustomAdapter.java

package com.devahoy.sample.ahoygson;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

public class CustomAdapter extends BaseAdapter {
    private LayoutInflater mInflater;
    private List<Post> mPosts;
    private ViewHolder mViewHolder;

    private Bitmap mBitmap;
    private Post mPost;
    private Activity mActivity;

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

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

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

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

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

            convertView.setTag(mViewHolder);

        } else {
            mViewHolder = (ViewHolder) convertView.getTag();
        }


        mPost = mPosts.get(position);

        if (mPost.getThumbnail() != null) {



            new AsyncTask<Void, Void, Void>() {
                @Override
                protected Void doInBackground(Void... params) {
                    try {
                        URL url = new URL(mPost.getThumbnail());
                        mBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());

                    } catch (MalformedURLException e) {

                    } catch (IOException e) {

                    }
                    return null;
                }
            }.execute();


            mViewHolder.thumbnail.setImageBitmap(mBitmap);
        }

        // ถ้าใช้ Picasso ก็ uncomment ข้างล้างนี้ แล้วลบ AsyncTask ออก
        // Picasso.with(mActivity)
        //    .load(mPost.getThumbnail())
        //    .into(mViewHolder.thumbnail);

        mViewHolder.author.setText(mPost.getAuthor());
        mViewHolder.title.setText(mPost.title);
        mViewHolder.date.setText(mPost.date);

        return convertView;
    }

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

MainActivity.java

package com.devahoy.sample.ahoygson;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.ListView;

import com.google.gson.Gson;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;


public class MainActivity extends ActionBarActivity {

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

    private ListView mListView;
    private CustomAdapter mAdapter;

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

        mListView = (ListView) findViewById(R.id.listView);

        new SimpleTask().execute(URL);
    }

    private class SimpleTask extends AsyncTask<String, Void, String> {

        @Override
        protected void onPreExecute() {
            // Create Show ProgressBar
        }

        protected String doInBackground(String... urls)   {
            String result = "";
            try {

                HttpGet httpGet = new HttpGet(urls[0]);
                HttpClient client = new DefaultHttpClient();

                HttpResponse response = client.execute(httpGet);

                int statusCode = response.getStatusLine().getStatusCode();

                if (statusCode == 200) {
                    InputStream inputStream = response.getEntity().getContent();
                    BufferedReader reader = new BufferedReader
                            (new InputStreamReader(inputStream));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        result += line;
                    }
                }

            } catch (ClientProtocolException e) {

            } catch (IOException e) {

            }
            return result;
        }

        protected void onPostExecute(String jsonString)  {
            // Dismiss ProgressBar
            showData(jsonString);
        }
    }

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


        mAdapter = new CustomAdapter(this, posts);
        mListView.setAdapter(mAdapter);
    }

}

Post.java

package com.devahoy.sample.ahoygson;

public class Post {
    int id;
    String url;
    String title;
    String date;
    String author;
    String thumbnail;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getTitle() {
        return title;
    }

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

    public String getDate() {
        return date;
    }

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

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getThumbnail() {
        return thumbnail;
    }

    public void setThumbnail(String thumbnail) {
        this.thumbnail = thumbnail;
    }
}

post.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">


    <ImageView
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:layout_marginRight="8dp"
        android:id="@+id/post_thumbnail"
        android:src="@drawable/ic_launcher"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Title"
        android:textSize="16sp"
        android:textStyle="bold"
        android:layout_marginTop="8dp"
        android:id="@+id/post_title"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/post_thumbnail"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Author Name"
        android:id="@+id/post_author"
        android:layout_marginTop="8dp"
        android:layout_below="@+id/post_title"
        android:layout_alignLeft="@+id/post_title"
        android:layout_alignStart="@+id/post_title"/>
    <TextView android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="Date"
              android:id="@+id/post_date"
              android:layout_marginRight="8dp"
              android:layout_alignTop="@+id/post_author"
              android:layout_alignParentRight="true"
              android:layout_alignParentEnd="true"/>
</RelativeLayout>