Android Development Steps

Get JSON Data

Create new empty project volleyGetJson

Add library in Graddle Dependencies

// volley library

implementation ‘com.android.volley:volley:1.1.1’

// image loading library

implementation ‘com.squareup.picasso:picasso:2.71828’

Add INTERNET permission in AndroidManifest

<uses-permission android:name="android.permission.INTERNET"/>

Update activity_main layout

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

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"

tools:context=".MainActivity">

<androidx.cardview.widget.CardView

android:id="@+id/idCVCourse"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="10dp"

android:elevation="10dp"

android:visibility="gone"

app:cardCornerRadius="8dp">

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="vertical">

<ImageView

android:id="@+id/idIVCourse"

android:layout_width="match_parent"

android:layout_height="300dp"

android:layout_margin="5dp" />

<TextView

android:id="@+id/idTVCourseName"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="5dp"

android:padding="5dp"

android:text="Course Name "

android:textColor="@color/black"

android:textSize="18sp"

android:textStyle="bold" />

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="5dp"

android:orientation="horizontal"

android:weightSum="2">

<TextView

android:id="@+id/idTVBatch"

android:layout_width="0dp"

android:layout_height="wrap_content"

android:layout_weight="1"

android:padding="5dp"

android:text="Batch"

android:textColor="@color/black" />

<TextView

android:id="@+id/idTVTracks"

android:layout_width="0dp"

android:layout_height="wrap_content"

android:layout_weight="1"

android:padding="5dp"

android:text="Tracks"

android:textColor="@color/black" />

</LinearLayout>

</androidx.cardview.widget.CardView>

<ProgressBar

android:id="@+id/idLoadingPB"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerInParent="true"

android:visibility="visible" />

</RelativeLayout>

Update MainActivity.java

import android.os.Bundle;

import android.view.View;

import android.widget.ImageView;

import android.widget.ProgressBar;

import android.widget.TextView;

import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import androidx.cardview.widget.CardView;

import com.android.volley.Request;

import com.android.volley.RequestQueue;

import com.android.volley.Response;

import com.android.volley.VolleyError;

import com.android.volley.toolbox.JsonObjectRequest;

import com.android.volley.toolbox.Volley;

import com.squareup.picasso.Picasso;

import org.json.JSONException;

import org.json.JSONObject;

public class MainActivity extends AppCompatActivity {

// creating variables for our textview,

// imageview,cardview and progressbar.

private TextView courseNameTV, courseTracksTV, courseBatchTV;

private ImageView courseIV;

private ProgressBar loadingPB;

private CardView courseCV;

// below line is the variable for url from

// where we will be querying our data.

String url = "http://tutorial.razzi.my/android101/json/get/";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

// in below line we are initializing our all views.

loadingPB = findViewById(R.id.idLoadingPB);

courseCV = findViewById(R.id.idCVCourse);

courseNameTV = findViewById(R.id.idTVCourseName);

courseTracksTV = findViewById(R.id.idTVTracks);

courseBatchTV = findViewById(R.id.idTVBatch);

courseIV = findViewById(R.id.idIVCourse);

// creating a new variable for our request queue

RequestQueue queue = Volley.newRequestQueue(MainActivity.this);

// as our data is in json object format so we are using

// json object request to make data request from our url.

// in below line we are making a json object

// request and creating a new json object request.

// inside our json object request we are calling a

// method to get the data, "url" from where we are

// calling our data,"null" as we are not passing any data.

// later on we are calling response listener method

// to get the response from our API.

JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {

@Override

public void onResponse(JSONObject response) {

// inside the on response method.

// we are hiding our progress bar.

loadingPB.setVisibility(View.GONE);

// in below line we are making our card

// view visible after we get all the data.

courseCV.setVisibility(View.VISIBLE);

try {

// now we get our response from API in json object format.

// in below line we are extracting a string with its key

// value from our json object.

// similarly we are extracting all the strings from our json object.

String courseName = response.getString("courseName");

String courseTracks = response.getString("courseTracks");

String courseMode = response.getString("courseMode");

String courseImageURL = response.getString("courseimg");

// after extracting all the data we are

// setting that data to all our views.

courseNameTV.setText(courseName);

courseTracksTV.setText(courseTracks);

courseBatchTV.setText(courseMode);

// we are using picasso to load the image from url.

Picasso.get().load(courseImageURL).into(courseIV);

} catch (JSONException e) {

// if we do not extract data from json object properly.

// below line of code is use to handle json exception

e.printStackTrace();

}

}, new Response.ErrorListener() {

// this is the error listener method which

// we will call if we get any error from API.

@Override

public void onErrorResponse(VolleyError error) {

// below line is use to display a toast message along with our error.

Toast.makeText(MainActivity.this, "Fail to get data..", Toast.LENGTH_SHORT).show();

}

});

// at last we are adding our json

// object request to our request

// queue to fetch all the json data.

queue.add(jsonObjectRequest);

}

Post JSON Data

Create new empty project volleyPostJson

Add library in Graddle Dependencies

// volley library

implementation ‘com.android.volley:volley:1.1.1’

Add INTERNET permission in AndroidManifest

<uses-permission android:name="android.permission.INTERNET"/>

Update activity_main layout

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

tools:context=".MainActivity">

<EditText

android:id="@+id/idEdtName"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="10dp"

android:layout_marginTop="40dp"

android:hint="Enter your name" />

<EditText

android:id="@+id/idEdtEmail"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="10dp"

android:hint="Enter your email" />

<Button

android:id="@+id/idBtnPost"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="20dp"

android:text="Send Data to API"

android:textAllCaps="false" />

<TextView

android:id="@+id/idTVResponse"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="10dp"

android:gravity="center_horizontal"

android:text="Response"

android:textAlignment="center"

android:textSize="15sp" />

<ProgressBar

android:id="@+id/idLoadingPB"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:visibility="gone" />

</LinearLayout>

Update MainActivity.java

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ProgressBar;

import android.widget.TextView;

import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import com.android.volley.Request;

import com.android.volley.RequestQueue;

import com.android.volley.VolleyError;

import com.android.volley.toolbox.StringRequest;

import com.android.volley.toolbox.Volley;

import org.json.JSONException;

import org.json.JSONObject;

import java.util.HashMap;

import java.util.Map;

public class MainActivity extends AppCompatActivity {

// creating variables for our edittext,

// button, textview and progressbar.

private EditText nameEdt, emailEdt;

private Button postDataBtn;

private TextView responseTV;

private ProgressBar loadingPB;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

// initializing our views

nameEdt = findViewById(R.id.idEdtName);

emailEdt = findViewById(R.id.idEdtEmail);

postDataBtn = findViewById(R.id.idBtnPost);

responseTV = findViewById(R.id.idTVResponse);

loadingPB = findViewById(R.id.idLoadingPB);

// adding on click listener to our button.

postDataBtn.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

// validating if the text field is empty or not.

if (nameEdt.getText().toString().isEmpty() && emailEdt.getText().toString().isEmpty()) {

Toast.makeText(MainActivity.this, "Please enter both the values", Toast.LENGTH_SHORT).show();

return;

}

// calling a method to post the data and passing name and email.

postDataUsingVolley(nameEdt.getText().toString(), emailEdt.getText().toString());

}

});

}

private void postDataUsingVolley(String name, String email) {

// url to post data

String url = "http://tutorial.razzi.my/android101/json/post/register.php";

loadingPB.setVisibility(View.VISIBLE);

// creating a new variable for request queue

RequestQueue queue = Volley.newRequestQueue(MainActivity.this);

// calling a string

// request method to post the data to API

// i.e. calling a post method.

StringRequest request = new StringRequest(Request.Method.POST, url, new com.android.volley.Response.Listener<String>() {

@Override

public void onResponse(String response) {

// inside on response method we are

// hiding our progress bar

// and setting data to edit text as empty

loadingPB.setVisibility(View.GONE);

nameEdt.setText("");

emailEdt.setText("");

// on below line we are displaying a success toast message.

Toast.makeText(MainActivity.this, "Data added to API", Toast.LENGTH_SHORT).show();

try {

// on below line we are parsing the response

// to json object to extract data from it.

JSONObject respObj = new JSONObject(response);

// below are the strings which we

// extract from our json object.

String name = respObj.getString("name");

String email = respObj.getString("email");

// setting the strings to text view.

responseTV.setText("Name : " + name + "\n" + "Email : " + email);

} catch (JSONException e) {

e.printStackTrace();

}

}, new com.android.volley.Response.ErrorListener() {

@Override

public void onErrorResponse(VolleyError error) {

// method to handle errors.

Toast.makeText(MainActivity.this, "Fail to get response = " + error, Toast.LENGTH_SHORT).show();

}

}) {

@Override

protected Map<String, String> getParams() {

// below line we are creating a map for

// storing our values in key and value pair.

Map<String, String> params = new HashMap<String, String>();

// passing key

// and value pair to parameters.

params.put("name", name);

params.put("email", email);

// returning params.

return params;

}

};

// make

// a json object request.

queue.add(request);

}

index.php

-----

<?php

$output = '{"courseName":"Android Development","courseimg":"https://i.ibb.co/XZPvkqd/bookandroid.png","courseMode":"Online","courseTracks":"50 Tracks"}';
echo $output;

-----

<?php

$myObj = new stdClass();

$myObj->name=$_POST["name"];

$myObj->email=$_POST["email"];

$myJSON = json_encode($myObj);

echo $myJSON;

apply.html

-----

<br/>

<br/>

</form>

Android Development Steps

Thursday, August 25, 2022

Working With Volley To Post And Get Data