Android JSON Parser

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;
    }
}

Output:

 

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