JSON Parser Tutorial
JSON (Javascript Object Notation) is a programming language . It is minimal, textual, and a subset of JavaScript. It is an alternative to XML.
Android provides support to parse the JSON object and array.
Advantage of JSON over XML
1) JSON is faster and easier than xml for AJAX applications.
2) Unlike XML, it is shorter and quicker to read and write.
3) It uses array.
json object
A JSON object contains key/value pairs like map. The keys are strings and the values are the JSON types. Keys and values are separated by comma. The { (curly brace) represents the json object.
"employee": {
"name": "sachin",
"salary": 56000,
"married": true
}
}
json array
The [ (square bracket) represents the json array.
Let's take another example of json array.
[
{"id":"101","name":" VIKASH SINGH","salary":"50000"},
{"id":"102","name":"shubham singh","salary":"60000"}
]
}
Example of android JSON parsing
activity_main.xml
Drag the one textview from the pallete. Now the activity_main.xml file will look like this:
File: activity_main.xml
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="75dp"
android:layout_marginTop="46dp"
android:text="TextView" />
</RelativeLayout>
Activity class
Let's write the code to parse the xml using dom parser.
File: MainActivity.java
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity {
public static final String JSON_STRING="{\"employee\":{\"name\":\"Sachin\",\"salary\":56000}}";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textView1=(TextView)findViewById(R.id.textView1);
try{
JSONObject emp=(new JSONObject(JSON_STRING)).getJSONObject("employee");
String empname=emp.getString("name");
int empsalary=emp.getInt("salary");
String str="Employee Name:"+empname+"\n"+"Employee Salary:"+empsalary;
textView1.setText(str);
}catch (Exception e) {e.printStackTrace();}
}
}
Output:
Parsing JSONArray in Android
By the help of JSONArray class, you can parse the JSONArray containing the JSON Objects. Let's see the simple example to parse the json array.
File: MainActivity.java
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView output = (TextView) findViewById(R.id.textView1);
String strJson="{ \"Employee\" :[{\"id\":\"101\",\"name\":\"Sonoo Jaiswal\",\"salary\":\"50000\"},{\"id\":\"102\",\"name\":\"Vimal Jaiswal\",\"salary\":\"60000\"}] }";
String data = "";
try {
// Create the root JSONObject from the JSON string.
JSONObject jsonRootObject = new JSONObject(strJson);
//Get the instance of JSONArray that contains JSONObjects
JSONArray jsonArray = jsonRootObject.optJSONArray("Employee");
//Iterate the jsonArray and print the info of JSONObjects
for(int i=0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
int id = Integer.parseInt(jsonObject.optString("id").toString());
String name = jsonObject.optString("name").toString();
float salary = Float.parseFloat(jsonObject.optString("salary").toString());
data += "Node"+i+" : \n id= "+ id +" \n Name= "+ name +" \n Salary= "+ salary +" \n ";
}
output.setText(data);
} catch (JSONException e) {e.printStackTrace();}
}
}
Output:
