This example is an improved version of my previous example Android GridView Example. Instead of using static images to display the grid items, lets make this example more realistic by downloading the data in realtime from server and render the grid items.
Without wasting much time, let us jump straight into what it takes to build this kind of GridView. You need to follow the following steps to complete this example.
1. Add GridView in Activity Layout
2. Declare GridView Item Layout
3. Adding Internet Permission
4. Adding Picasso Image Downloading Library
5. Create a GridView Custom Adapter
6. Download Data and Hook it to Activity
7. Handle GridView Click Event
8. Create Details Activity Layout
9. Completing the Details Activity
10. Custom Activity Transition in GridView
1. Add GridView in Activity Layout
First, create a new android project. For this example, I prefer to use Android Studio. Create a new layout file to your project res/layout folder and name it as activity_grid_view.xml. And add the following code blocks.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#f0f0f0">
<GridView
android:id="@+id/gridView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:columnWidth="100dp"
android:drawSelectorOnTop="true"
android:gravity="center"
android:numColumns="auto_fit"
android:stretchMode="columnWidth"
android:verticalSpacing="5dp"
android:focusable="true"
android:clickable="true"/>
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/progressBar"
android:layout_centerInParent="true"
android:visibility="gone"/>
</RelativeLayout>
The above layout is pretty straight forward. We have declared an GridView and a ProgressBar in activity layout. The progress bar will be displayed when the data is being downloaded.
2. Declare GridView Item Layout
Let us now add another file named grid_item_layout.xml to res/layout folder. This layout will be used by custom grid adapter for laying out individual grid item. For the sake of simplicity, we are adding an ImageView and a TextView.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:background="@drawable/grid_color_selector"
android:orientation="vertical"
android:padding="5dp">
<ImageView
android:id="@+id/grid_item_image"
android:layout_width="100dp"
android:layout_height="100dp"
android:scaleType="centerCrop"/>
<TextView
android:id="@+id/grid_item_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:gravity="center"
android:maxLines="2"
android:ellipsize="marquee"
android:textSize="12sp" />
</LinearLayout>
3. Adding Internet Permission
You might be aware that, Android application must declare all the permissions that are required for application. As we need to download the data form server, we need to add the INTERNET permission. Add the following line to AndroidManifest.xml file.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.javatechig.gridviewexample">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
<activity
android:name=".GridViewActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".DetailsActivity" />
</application>
</manifest>
Notice that we have also declared all the activities used in the application.
4. Adding Picasso Image Downloading Library
Android open source developer community brings some of the interesting libraries that can be integrated easily to Android applications. They serves a great deal of purpose and saves lot of time. Here in this example, I am talking about Picasso image loading library. We will add Picasso library for downloading and caching of images. Visit here to learn more about how to use Picasso library in Android.
You can add the Picasso library by adding the following dependency to the build.gradle file.
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:21.0.3'
compile 'com.squareup.picasso:picasso:2.5.2'
}
5. Create a GridView Custom Adapter
A grid view is an adapter view. It requires an adapter to render the collection of data items. Add a new class named GridViewAdapter.java to your project and add the following code snippets.
package com.javatechig.gridviewexample;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.text.Html;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.squareup.picasso.Picasso;
public class GridViewAdapter extends ArrayAdapter<GridItem> {
private Context mContext;
private int layoutResourceId;
private ArrayList<GridItem> mGridData = new ArrayList<GridItem>();
public GridViewAdapter(Context mContext, int layoutResourceId, ArrayList<GridItem> mGridData) {
super(mContext, layoutResourceId, mGridData);
this.layoutResourceId = layoutResourceId;
this.mContext = mContext;
this.mGridData = mGridData;
}
/**
* Updates grid data and refresh grid items.
* @param mGridData
*/
public void setGridData(ArrayList<GridItem> mGridData) {
this.mGridData = mGridData;
notifyDataSetChanged();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ViewHolder holder;
if (row == null) {
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder = new ViewHolder();
holder.titleTextView = (TextView) row.findViewById(R.id.grid_item_title);
holder.imageView = (ImageView) row.findViewById(R.id.grid_item_image);
row.setTag(holder);
} else {
holder = (ViewHolder) row.getTag();
}
GridItem item = mGridData.get(position);
holder.titleTextView.setText(Html.fromHtml(item.getTitle()));
Picasso.with(mContext).load(item.getImage()).into(holder.imageView);
return row;
}
static class ViewHolder {
TextView titleTextView;
ImageView imageView;
}
}
Notice the following in the above code snippets,
- The
setGridData()method updates the data display on GridView. - The
Picasso.with().load()method is used to download the image from url and display on image view. - The GridViewAdapter class constructor requires the id of the grid item layout and the list of data to operate on.
- You might be surprised, where is the
GridItemclass came from. Its not a magic, we need to addGridItem.javaclass to our project. The GridItem class looks as follows.
6. Download Data and Hook it to Activity
Now we will be heading towards hooking the adapter to GridView and make it functional. Create a new Java class and name it as GridViewActivity.java and perform the following steps.
- Override the
onCreate()method and set the layout by callingsetContentView()method - Initialize the GridView and ProgressBar component by using their declared layout id.
- Initialize the
CustomGridViewadapter by passing the grid row layout id and the list ofGridItemobjects. - Use AsyncTask to download data from server, once download is successful read the stream JSON response.
- Parse the JSON string into the list of GridItem objects. Once downloading and parsing is completed, in
onPostExecute()callback update the UI elements.
The following code does all the above steps as described. Add the following code to GridViewActivity class.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ProgressBar;
import android.widget.Toast;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class GridViewActivity extends ActionBarActivity {
private static final String TAG = GridViewActivity.class.getSimpleName();
private GridView mGridView;
private ProgressBar mProgressBar;
private GridViewAdapter mGridAdapter;
private ArrayList<GridItem> mGridData;
private String FEED_URL = "http://javatechig.com/?json=get_recent_posts&count=45";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gridview);
mGridView = (GridView) findViewById(R.id.gridView);
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
//Initialize with empty data
mGridData = new ArrayList<>();
mGridAdapter = new GridViewAdapter(this, R.layout.grid_item_layout, mGridData);
mGridView.setAdapter(mGridAdapter);
//Start download
new AsyncHttpTask().execute(FEED_URL);
mProgressBar.setVisibility(View.VISIBLE);
}
//Downloading data asynchronously
public class AsyncHttpTask extends AsyncTask<String, Void, Integer> {
@Override
protected Integer doInBackground(String... params) {
Integer result = 0;
try {
// Create Apache HttpClient
HttpClient httpclient = new DefaultHttpClient();
HttpResponse httpResponse = httpclient.execute(new HttpGet(params[0]));
int statusCode = httpResponse.getStatusLine().getStatusCode();
// 200 represents HTTP OK
if (statusCode == 200) {
String response = streamToString(httpResponse.getEntity().getContent());
parseResult(response);
result = 1; // Successful
} else {
result = 0; //"Failed
}
} catch (Exception e) {
Log.d(TAG, e.getLocalizedMessage());
}
return result;
}
@Override
protected void onPostExecute(Integer result) {
// Download complete. Let us update UI
if (result == 1) {
mGridAdapter.setGridData(mGridData);
} else {
Toast.makeText(GridViewActivity.this, "Failed to fetch data!", Toast.LENGTH_SHORT).show();
}
mProgressBar.setVisibility(View.GONE);
}
}
String streamToString(InputStream stream) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream));
String line;
String result = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
// Close stream
if (null != stream) {
stream.close();
}
return result;
}
/**
* Parsing the feed results and get the list
* @param result
*/
private void parseResult(String result) {
try {
JSONObject response = new JSONObject(result);
JSONArray posts = response.optJSONArray("posts");
GridItem item;
for (int i = 0; i < posts.length(); i++) {
JSONObject post = posts.optJSONObject(i);
String title = post.optString("title");
item = new GridItem();
item.setTitle(title);
JSONArray attachments = post.getJSONArray("attachments");
if (null != attachments && attachments.length() > 0) {
JSONObject attachment = attachments.getJSONObject(0);
if (attachment != null)
item.setImage(attachment.getString("url"));
}
mGridData.add(item);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
At this point you will be able to run the app and notice that the app will download the data from the server and display on GridView.
7. Handle GridView Click Event
Right now GridView is not responding to user clicks. Let us make it more functional by adding the following code.
mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
//Get item at position
GridItem item = (GridItem) parent.getItemAtPosition(position);
//Pass the image title and url to DetailsActivity
Intent intent = new Intent(GridViewActivity.this, DetailsActivity.class);
intent.putExtra("title", item.getTitle());
intent.putExtra("image", item.getImage());
//Start details activity
startActivity(intent);
}
});
When user clicks on a grid item, we will start another activity that displays the full screen image. You can start one activity form another by calling startActivity() method.
We need to pass the details of the item such as title, and image url for displaying it on DetailsActivity.
8. Create Details Activity Layout
Add a new layout file to res/layout directory, name it as activity_details_view.xml and add the following code snippets.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000"
android:orientation="vertical">
<ImageView
android:id="@+id/grid_item_image"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:scaleType="fitCenter" />
<TextView
android:id="@+id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="#00000c"
android:padding="10dp"
android:textColor="#fff"
android:textSize="20dp" />
</FrameLayout>
9. Completing the Details Activity
The DetailsActivity retrieves the details passed from GridViewActivity and renders the details on screen. Create a new class named DetailsActivity and add the following code snippets.
package com.javatechig.gridviewexample;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.text.Html;
import android.widget.ImageView;
import android.widget.TextView;
import com.squareup.picasso.Picasso;
public class DetailsActivity extends ActionBarActivity {
private TextView titleTextView;
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details_view);
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
String title = getIntent().getStringExtra("title");
String image = getIntent().getStringExtra("image");
titleTextView = (TextView) findViewById(R.id.title);
imageView = (ImageView) findViewById(R.id.grid_item_image);
titleTextView.setText(Html.fromHtml(title));
Picasso.with(this).load(image).into(imageView);
}
}
10. Custom Activity Transition in GridView
