A - Introduction
JSON is a light-weight data interchange format. It’s easy for human to read and write, for machines to parse and generate.
JSON is the best choice to replace XML when you want to interchange data from server side.
In this post - Parse JSON in Android, I’ll show you how to get JSON string from server and parse it in Android.
B - Sample JSON
This is the sample JSON I use in this post.
This JSON string contains some products’ information like: id, name, price, description,…
You can access this JSON string by the address: http://icetea09.com/blog-files/demo_json
{
"products": [
{
"id": "p200",
"name": "Canon 600D",
"price": "25",
"description" : "The best camera of Canon!",
"store": {
"store1": "xx xxxxx, yyy zzzz",
"store2": "xx xxxxx, yyy zzzz",
"store3": "xx xxxxx, yyy zzzz"
}
},
{
"id": "p201",
"name": "iPhone 5S",
"price": "576",
"description" : "Great smart phone!",
"store": {
"store1": "xx xxxxx, yyy zzzz",
"store2": "xx xxxxx, yyy zzzz",
"store3": "xx xxxxx, yyy zzzz"
}
},
{
"id": "p202",
"name": "Aquafina",
"price": "1",
"description" : "Pure water",
"store": {
"store1": "xx xxxxx, yyy zzzz",
"store2": "xx xxxxx, yyy zzzz",
"store3": "xx xxxxx, yyy zzzz"
}
},
{
"id": "p203",
"name": "HP HDX T16",
"price": "765",
"description" : "Perfect choice for entertainment",
"store": {
"store1": "xx xxxxx, yyy zzzz",
"store2": "xx xxxxx, yyy zzzz",
"store3": "xx xxxxx, yyy zzzz"
}
},
{
"id": "p204",
"name": "HTC One",
"price": "623",
"description" : "HTC One",
"store": {
"store1": "abc def",
"store2": "abc def",
"store3": "abc def"
}
},
{
"id": "p205",
"name": "Nikon ACB",
"price": "452",
"description" : "Nikon ACB",
"store": {
"store1": "xx xxxxx, yyy zzzz",
"store2": "xx xxxxx, yyy zzzz",
"store3": "xx xxxxx, yyy zzzz"
}
},
{
"id": "p206",
"name": "ABC XYZ",
"price": "1234",
"description" : "ABC XYZ",
"store": {
"store1": "abc def",
"store2": "abc def",
"store3": "abc def"
}
}
]
}
Note: Difference between { and [ in JSON string
The { represent for a JSON object and the [ represent for a JSON array.
So, when parsing the JSON string, you have to notice to call the correct method:
- getJSONArray(): when the JSON node start with [ - square bracket
- getJSONObject(): when the JSON node start with { - curly bracket
C - Demo Parse JSON in Android
1. Service Handler
First, create a new Android project.
Create a class to handle calling web service - ServiceHandler:
public class ServiceHandler {
static String response;
public static final int GET = 1;
public static final int POST = 2;
/***
* Make a service call and return response string
*/
public String makeServiceCall(String url, int method){
return this.makeServiceCall(url, method, null);
}
/***
* Make a service call and return response string
*/
public String makeServiceCall(String url, int method, List<NameValuePair> parans){
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpEntity httpEntity = null;
HttpResponse httpResponse = null;
if(method == POST){
HttpPost httpPost = new HttpPost(url);
if(parans != null){
httpPost.setEntity(new UrlEncodedFormEntity(parans));
}
httpResponse = httpClient.execute(httpPost);
}
else{
if(parans!=null){
String paramString = URLEncodedUtils.format(parans, "utf-8");
url += ("?" + paramString);
}
HttpGet httpGet = new HttpGet(url);
httpResponse = httpClient.execute(httpGet);
}
httpEntity = httpResponse.getEntity();
response = EntityUtils.toString(httpEntity);
} catch (Exception e) {
System.out.println("EXCEPTION: makeServiceCall --- " + e.getMessage());
}
return response;
}
}
The method makeServiceCall() will handle webservice call and return the respone string. It has 3 parameters:
- url: the URL to call web service
- method: GET or POST
- params: all parameters you want to submit to web service (optional)
2. ListView
In the Main Activity layout, add a ListView to display data in JSON string:
<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"
tools:context=".MainActivity" >
<ListView
android:id="@+id/lv_products"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" >
</ListView>
</RelativeLayout>
As you know , we need to create a custom layout, entity class and adapter for the ListView:
ListView item layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
android:orientation="vertical" >
<TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Product Name"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/tv_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Description"
android:textAppearance="?android:attr/textAppearanceSmall" />
<TextView
android:id="@+id/tv_price"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Price"
android:textAppearance="?android:attr/textAppearanceSmall" />
</LinearLayout>
Product entity class
public class Product {
String id;
String name;
float price;
String description;
String[] stores;
public Product(String id, String name, float price, String description) {
super();
this.id = id;
this.name = name;
this.price = price;
this.description = description;
}
public Product(String id, String name, float price, String description,
String[] stores) {
super();
this.id = id;
this.name = name;
this.price = price;
this.description = description;
this.stores = stores;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String[] getStores() {
return stores;
}
public void setStores(String[] stores) {
this.stores = stores;
}
}
ListView adapter class:
public class ListViewProductAdapter extends ArrayAdapter<Product> {
Context context;
int layoutResource;
List<Product> data;
public ListViewProductAdapter(Context context, int resource, List<Product> objects) {
super(context, resource, objects);
this.context = context;
this.layoutResource = resource;
this.data = objects;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
ProductHolder holder = null;
if(view == null){
LayoutInflater layoutInflater = ((Activity)context).getLayoutInflater();
view = layoutInflater.inflate(layoutResource, parent, false);
holder = new ProductHolder();
holder.tvName = (TextView)view.findViewById(R.id.tv_name);
holder.tvDescription = (TextView)view.findViewById(R.id.tv_description);
holder.tvPrice = (TextView)view.findViewById(R.id.tv_price);
view.setTag(holder);
}
else{
holder = (ProductHolder)view.getTag();
}
if (position % 2 == 1) {
view.setBackgroundColor(Color.WHITE);
} else {
view.setBackgroundColor(Color.parseColor("#DCE6CA"));
}
Product product = data.get(position);
holder.tvName.setText(product.getName());
holder.tvDescription.setText(product.getDescription());
holder.tvPrice.setText("Price: " + String.valueOf(product.getPrice()));
return view;
}
static class ProductHolder{
TextView tvName;
TextView tvPrice;
TextView tvDescription;
}
}
3. Create Async task to get and parse JSON string
In MainActivity class, create some variables and constants:
private ProgressDialog progressDialog;
private static String url = "http://icetea09.com/blog-files/demo_json";
// JSON Node names
private static final String TAG_PRODUCTS = "products";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_PRICE = "price";
private static final String TAG_DESCRIPTION = "description";
private static final String TAG_STORE = "store";
private static final String TAG_STORE1 = "store1";
private static final String TAG_STORE2 = "store2";
private static final String TAG_STORE3 = "store3";
// contacts JSONArray
JSONArray products = null;
// Hashmap for ListView
ArrayList<Product> productList;
ListView lvProducts;
Create an inner class of MainActivity named GetProducts.
This class extends AsyncTask, takes responsibility for getting the JSON string from server and parsing it into Product entity.
Finally, show all the data recieved to the ListView.
private class GetProducts extends AsyncTask<Void, Void, Void>{
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Please wait...");
progressDialog.setCancelable(false);
progressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
products = jsonObj.getJSONArray(TAG_PRODUCTS);
// looping through All Contacts
for (int i = 0; i < products.length(); i++) {
JSONObject p = products.getJSONObject(i);
String id = p.getString(TAG_ID);
String name = p.getString(TAG_NAME);
String description = p.getString(TAG_DESCRIPTION);
float price = Float.valueOf(p.getString(TAG_PRICE));
// Phone node is JSON Object
JSONObject store = p.getJSONObject(TAG_STORE);
String store1 = store.getString(TAG_STORE1);
String store2 = store.getString(TAG_STORE2);
String store3 = store.getString(TAG_STORE3);
// tmp hashmap for single contact
Product product = new Product(id, name, price, description);
productList.add(product);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (progressDialog.isShowing())
progressDialog.dismiss();
ListViewProductAdapter adapter = new ListViewProductAdapter(MainActivity.this, R.layout.lv_item_products, productList);
lvProducts.setAdapter(adapter);
}
}
And the result:
D - Download source code Parse JSON in Android
https://drive.google.com/file/d/0Bw3dwdSezn6fNXdpeGpWSjVMc0E/edit?usp=sharing
