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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