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Json Parsing in Android
Json Parsing in Android
JSon parsing is a short form for Java Script Object Notation. It is used to parse online http Json data.
Json data is in the form of objects (starts with { } braces) and arrays (starts with [ ]).
We use Json Parsing to handle Json data from Server Api and set it in our Android App or Website According to our design layout or choice..
In This post we use Json parsing and fetch some data from there.
We use a Json url from an Api for testing purposes, you can use any url if you know how to get that Json Values.
Json Url
https://reqres.in/api/products/
So, Create an Android Project and open it.
To use Json Parsing in Android, We will create a Httphandler class to handle http data and fetch values from their.
httphandler.java
import android.util.Log;
import android.util.Log;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
public class HttpHandler {
private static final String TAG = HttpHandler.class.getSimpleName();
public HttpHandler() {
}
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}
With this class we will handle and fetch all data from http url and use in our app
After that we have created
- Two textviews (1 for fetched object values and 2nd for fetched array values) to set fetched values on it.
- Button to execute async method.
- Edittext to get position value of array.
XML Code
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_margin="10dp"
tools:context=".Json_Parsing">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="16sp"
android:maxLines="7"
android:id="@+id/tv1"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxLines="7"
android:textSize="16sp"
android:id="@+id/tv2"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Get Data"
android:id="@+id/getbtn"/>
</LinearLayout>
After that in Java Code, We will create an Async Task class to execute that http handler class to fetch values from http json url.
Java Code
package studio.harpreet.sampleproject;
import androidx.appcompat.app.AppCompatActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONObject;
public class Json_Parsing extends AppCompatActivity {
String Json_string = "https://reqres.in/api/products/";
String objectsvalue = "",arrayvalue = ""; // objectvalue for combining some string and set on textview ,
// arrayvalue string to get value and show it on textview
EditText et;
TextView tv1,tv2;
Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_json__parsing);
et = findViewById(R.id.et);
tv1 = findViewById(R.id.tv1);
tv2 = findViewById(R.id.tv2);
btn = findViewById(R.id.getbtn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new GetData().execute();
}
});
}
private class GetData extends AsyncTask<Void,Void,Void>
{
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... voids) {
HttpHandler hh = new HttpHandler();
String jsonstr = hh.makeServiceCall(Json_string);
Log.e("TAG", "doInBackground: response from url "+jsonstr );
try {
if (jsonstr != null)
{
JSONObject jsonObject = new JSONObject(jsonstr); //because it starts from object class
String per_page = jsonObject.getString("per_page");
String total = jsonObject.getString("total");
String url = jsonObject.getJSONObject("support").getString("url");
String text = jsonObject.getJSONObject("support").getString("text");
objectsvalue = "per_page: "+per_page+"\n"
+"total: " +total+"\n"
+"url: "+ url +"\n"
+"text: "+ text;
JSONArray data_array = jsonObject.getJSONArray("data");
for(int i = 0; i < data_array.length(); i++)
{
JSONObject obj = data_array.getJSONObject(Integer.parseInt(et.getText().toString()));//sets to custom position
// i is your position
String id = obj.getString("id");
String name = obj.getString("name");
String year = obj.getString("year");
String color = obj.getString("color");
String pantone = obj.getString("pantone_value"); //all values are case-sensitive, must be same
arrayvalue = "id: "+id+"\n"+
"name: "+name+"\n"
+"year: "+year+"\n"
+"color: "+color+"\n"
+"pantone: "+pantone; // we have store value in a string variable. we can't set a value to textview from here
// we can only set a value from onpostexecute method.
// it's a process of do in background , on pre execute then do in background then
// on post execute
}
}
}
catch (Exception e)
{
Log.e("TAG", "doInBackground: "+e.getMessage() );
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
tv1.setText(arrayvalue);
tv2.setText(objectsvalue);
super.onPostExecute(aVoid);
}
}
}
Now, In Java Code, we have fetch all values with json object and json arrays. and set it on textviews by concat all string values.
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