JSON Parser ANdroid
JSON stands for the Javascript Object Notation. It is a programming language, minimal, textual, and a subset of JavaScript and an alternative to XML. We can parse the JSON object and array in Android.
Advantages of JSON over XML:
- Compared to XML, JSON is easier and faster for AJAX applications.
- Compared to XML, JSON is quicker and shorter to read and write.
- JSON uses an array.
- JSON is Human Readable.
- JSON is easy to parse.
Advantages of XML over JSON:
- XML supports Namespaces to allow for the sharing of standard structures.
- Compared to JSON, XML supports better representation for inheritance.
- XML is Human Readable.
- XML is easy to parse.
JSON object:
Similar to a map, the JSON object also contains key/value pairs, separated by a comma, where keys are strings and the values are the JSON types. The JSON object is represented by the { (curly brace).
Example:
{ "student": { "name": "Rohan", "id": 100, "class": 6 } } |
JSON array:
The JSON array is represented by the [ (square bracket).
Example 1:
["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"] |
Example 2:
{ "Student" : [ {"id":"1","name":"Rohan","marks":"80"}, {"id":"2","name":"Rohit","marks":"90"} ] } |
Parsing JSONArray in Android:
In the below example, we will parse the JSONArray containing the JSON Objects using the JSONArray class.
Example:
activity_main.xml
In the activity_main.xml file, we will drag a Textview from the palette.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <ListView android:id="@+id/user_list" android:layout_width="fill_parent" android:layout_height="wrap_content" android:dividerHeight="1dp" /> </LinearLayout> |
List_row.xml:
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:padding="5dip" > <TextView android:id="@+id/name" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textStyle="bold" android:textSize="17dp" /> <TextView android:id="@+id/designation" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/name" android:layout_marginTop="7dp" android:textColor="#343434" android:textSize="14dp" /> <TextView android:id="@+id/location" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBaseline="@+id/designation" android:layout_alignBottom="@+id/designation" android:layout_alignParentRight="true" android:textColor="#343434" android:textSize="14dp" /> </RelativeLayout> |
Activity class:
In the MainActivity.java file, we will write the code to parse the XML using the JSON parser.
package com.example.radioapp; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.SimpleAdapter; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.util.ArrayList; import java.util.HashMap; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); String jsonStr = getListData(); try{ ArrayList<HashMap<String, String>> userList = new ArrayList<>(); ListView lv = (ListView) findViewById(R.id.user_list); JSONObject jObj = new JSONObject(jsonStr); JSONArray jsonArry = jObj.getJSONArray("users"); for(int i=0;i<jsonArry.length();i++){ HashMap<String,String> user = new HashMap<>(); JSONObject obj = jsonArry.getJSONObject(i); user.put("name",obj.getString("name")); user.put("designation",obj.getString("designation")); user.put("location",obj.getString("location")); userList.add(user); } ListAdapter adapter = new SimpleAdapter(MainActivity.this, userList, R.layout.list_row,new String[]{"name","designation","location"}, new int[]{R.id.name, R.id.designation, R.id.location}); lv.setAdapter(adapter); } catch (JSONException ex){ Log.e("JsonParser Example","unexpected JSON exception", ex); } } private String getListData() { String jsonStr = "{ \"users\" :[" + "{\"name\":\"A\",\"designation\":\"Leader\",\"location\":\"City1\"}" + ",{\"name\":\"B\",\"designation\":\"Secretary\",\"location\":\"City2\"}" + ",{\"name\":\"C\",\"designation\":\"Accountant\",\"location\":\"City3\"}] }"; return jsonStr; } } |
