Android volley get json

This post shows how to translate text between languages with an example.

Identify Language of Text with Firebase API Android Example

This post explains how to build a feature in android app that identifies the language of given text.

Organize Photos by Content Android Example

This post explains how to create in android a feature that lets user organize photos by its content.

Android Barcode Scanning Example

This post explains how to develop barcode scanning feature in android app using Firebase machine learning kit which provides barcode scanning API.

Extracting Text from Images Android

To recognize and extract text from images, Firebase ML kit can be used. Firebase ML kit offers machine learning features and is based on Google ML technologies.

Google Places SDK for Android Tutorial

Using Google places SDK for Android, current places, place details, nearby places and photos associated with a place can be displayed in apps and place search capability can be developed.

One of the excellent features of Android is that app’s information and features can be displayed as mini apps on home screens. These mini apps are called widgets.

Android MotionLayout Examples

MotionLayout is a subclass of ConstraintLayout. It allows you to animate property changes of UI elements which are part of a layout.

Android Fragments Transition Animation Example

To minimize the number of un-installations of your app, you need to build it in such way that it performs well, works on all devices and is user friendly.

Model View ViewModel MVVM Android Example

Model View ViewModel (MVVM) is an architectural pattern applied in applications to separate user interface code from data and business logic.

Android Model View Presenter MVP Pattern Example

If you want to build android apps which can be tested and modified easily, you need to implement user interface architectural pattern in your app.

Android Kotlin ListView Example

It is very common in most of the applications that a list of data items is displayed in UI. In android applications, list of data items can be shown to users using ListView.

About

Android app development tutorials and web app development tutorials with programming examples and code samples.

Источник

Android Volley Tutorial | Get,Post Request With Listview,Recyclerview

Today’s article is about Android Volley Tutorial with examples.

Below is the list of the practical examples on how to use volley in android.

1. Android Volley GET Request With Parameters

Generally, Developers use GET request when there are no parameters in the URL but still you can use GET request with parameters using volley.

For making http GET request using Volley, we need to write parameters and also it’s values in the URL itself.

For example, something like below line

Watch GET request

Load the below video to see volley GET request with parameters.

Step 1. Permissions and gradle files

First of all, create a brand new project in android studio.

In this process, select “Empty Activity” as a default template.

Now we need to define INTERNET permission to use the internet of the android device.

Add the below line in AndroidManifest.xml file.

To use the volley library in this project, add the following line in build.gradle(Module: app) file.

Above line fetch all the classes from volley library so that we can import them easily in our android studio project.

Step 2. Making Second Activity

Create a new activity and give it a name “Second Activity.”

In your activity_second.xml file, add the following code lines

Above XML file includes two text views.

One text view will hold the value of first name and second one will get the value of hobby.

Now in SecondActivity.java file, write down the following code snippet

Here, we are also taking two text views.

I have set the text value of both the text views using two public variables which we will write in the Main Activity.

Because these string variables (publicFirstName and publicHobby) are public, we can use them in class of our project using MainActivity. keyword.

Step 3. Default Activity Tasks

When you created new project in android studio, system should have generated two files automatically.

One is activity_main.xml and MainActiivity.java

Now in activity_main.xml file, write down the below coding structure

Several UI widgets are there in the above file. One text view, two edit texts and one button.

Text view is just saying the name of the company or app.

Among two edit texts, one will get the value of user name and other will get the password from the user.

When the user clicks the button, system will make the https call.

Now in the MainActivity.java file, add the below coding snippet.

Main Activity Writings

Main activity java files has the important code lines to understand.

So consider the below code first,

First line making an empty string variable. We will insert the whole URL in this variable later.

Second line is creating an objects of edit text classes. Third line will give the button object.

Fourth line is creating two public static string variables. We can use these public variables anywhere in our whole project. We have used these variables in SecondActivity.java class.

Inside onCreate() method, compiler will first attach the IDs to various Widgets.

Then it will set the onClick() method for the button.

Code for button click event is as the following

Compiler will execute the getVolley() method, when the user clicks the button.

First of all, Compiler will define the two final string variables (username and password).

Edit text etUname will give it’s value in string format to username.

password will get it’s text from etPass edit text.

Now a string variable URLline will get the full URL as per the below line

As you can see that we have attach the parameters at the end of php file using ? sign.

We can separate two parameters using & sign.

Possible URL structure can be like the below line

Now after this coding, compiler will create the object of StringRequest class.

Look at the following code line

Here, first parameter is saying that the type of http request is GET and second parameter is getting the URL structure in string format.

After this much execution, compiler have make GET request to the remote server.

When the server gives JSON response, compiler calls the onResposne() method.

Inside onResposne() method, there is a method named parseData().

parseData() will take the JSON response in string format as it’s parameter.

Following is the code structure for parseData() method.

Compiler will first parse the json object from the response.

Then it will check the key “status“. If it’s value id “true” then it will create one json array.

This json array is parse using the “data” field.

After this, compiler will create one for loop. Inside this for loop, compiler will give the value to public string variables. (publicFirstName and publicHobby.)

After this, compiler will open second activity.

2. Android Volley POST Request With Parameters

I will write about Android Volley Post Request With Parameters Example today.

You will learn to make volley post request with parameters in android studio.

If we do not need to pass parameters in volley request then we generally use GET request. It will simply make http call without any parameter and will give us JSON response.

See the Parameters

The following video demonstrates the working of this android volley post request example.

Step 1. Permission and Dependency

Make a new project in android studio and set the default activity as the “Empty activity.”

When we want to make http calls to remote server, we need to use internet of android device.

For this, we have to define INTERNET permission in our project.

Add the below line in AndroidManifest.xml file.

INTERNET permission is not harmful to user privacy so we do not need to ask for runtime permission in this example.

Now in your build.gradle(Module: app) file, add the below line

Above line will enable us to use some classes of volley library and we can import them in our project.

Step 2. Making Hobby Activity

Create a new activity and give it a name “HobbyActivity.”

System will create two files : activity_hobby.xml and HobbyActivity.java

In the activity_hobby.xml file, write down the following code lines

There are two text views are there.

When we call the web service, remote server will send us some data in JSON format. Among these data, we will parse first name and hobby.

Above two text views will hold first name and hobby data.

Now in the HobbyActivity.java, add the below code structure

As you can see that, I have taken two text views.

These text views are getting their values with the help of two variables.

One is firstName and other is hobby.

These variables are defined in the MainActivity.java as the public identifier. Because these variables are public so we can use them in HobbyActivity.java file.

Step 3. Main Activity Files

When you have created new project in android studio, system must have created two files automatically.

One is activity_main.xml and other one is MainActivity.java

Source code for activity_main.xml is as the following

Main XML file will create one login template. Here user will insert the login credentials.

It includes One text view, two edit text and one button widget.

Text view is static and it includes the header name.

One edit text will receive the value of user name and other one will hold the value of password.

When the user will click the button, we will make the POST http call with parameters using volley library.

Now write down the following code block in MainActivity.java file.

Looking Closely at Main Code

First of all, consider the below snippet

First line is the string variable. It include the URL in string format.

Second one is defining the objects of Edit text class and third one is giving us the object of Button class.

Fourth code line is making two public string variables. We have used these public variables in Hobby Activity also.

Now read the below code structure

When the user clicks the button, compiler will call loginUser() method.

Coding lines for loginUser() method is as the following

Two string variables username and password are defined at the starting of this loginUser() method.

username will get it’s value in string format from etUname which is an edit text.

Other edit text etPass will give the value of password to the string variable password.

After this, compiler will create the object of the StringRequest class.

Look at the below line

Here, Request.Method.POST will tell volley to make POST request.

URLline is the string variable which holds the full URL structure.

Now read the following source code

Above code will create one hash map. This map has two children.

One is with key->”username” and value->string variable (username)

Another is with key ->”password” and value -> string variable (password)

This hash map will provide parameters to our URL.

After successful call to the web service, compiler will execute onResponse() method.

onResponse() method will create one Toast which will provide full JSON response.

After Toast, compiler will call parseData() method. Parameter for this method is the JSON response in the string format.

Code structure for parseData() method is as the following

Here, compiler will first parse the JSON object.

Then it will check the field “status“. If it’s value is true then it will parse one JSON array.

Then it will create one for loop. Inside this for loop, compiler will parse first name and hobby.

And then it will save this first name and hobby in public string variables.

After for loop, system will open a new activity called “Hobby Activity”, which we have already created in Step 2.

3. Android JSON Parsing Using Volley And Display With RecyclerView

Android JSON Parsing Using Volley And Display With RecyclerView is today’s tutorial.

First of all, we will parse the JSON from URL using Volley.

Then we will populate a recyclerview using the data fetched from the JSON.

Generally, we need to make http calls to use the data on the remote server but volley simplifies this process.

Volley will reduce the number of Coding lines to make GET or POST calls to the web service.

We will fetch the information like name, country, city and image URL from the JSON.

Along with recyclerview, we will also use cardview to make it looking more attractive.

RecyclerView From Volley

Step 1. Internet Permission In Manifest

Internet is the basic requirement to call JSON from the remote server.

Add the below line in the AndroidManifest.xml file

Here, we do not need to code for runtime permissions because internet is the normal or basic permission.

Normal permission means that it is lesser harming to the user privacy.

Step 2. Some Dependencies

It is time write some dependencies in the build.gradle(Module: app) file as per the below

I have added these lines for four different purposes.

First one is for volley library. It will enable us to use volley classes with any other integrations.

Second line is for picasso library which helps us to fetch the image from URL seamlessly.

Third line will allow us to use the recyclerview.

And finally, fourth line will give us the required classes for the usage of cardview.

Step 3. XML File For RecyclerView

Let us create an XML file under res->layout directory.

Give it a name rv_one.xml and add the following code in it

This file will provide the view structure to every row of the recyclerview.

I have taken one imaheview and three textviews in this file.

All these widgets are under the cardview that will create card layout to every row item.

Step 4. Data Model

Let us create a new class and give it a name DataModel.java

Code structure for DataModel.java is as the following

Step 5. Required Adapter

Adapter class will help us to populate the recyclerview.

Make a new JAVA class and give it a name RvAdapter.java

Code block for RvAdapter.java is as the following block

Consider the below lines

First compiler will define the objects of LayoutInflater and arraylist.

Constructor will give us context and arraylist via it’s parameters.

Look at the following code block

First line is loading the Image from the URL.

Compiler will use Picasso library here. It will get the url using getter method.

Compiler will write the name, country and city using related getter methods from the objects of the arraylist.

Step 6. Main Modifications

Add the following lines in activity_main.xml file

It includes one textview and recyclerview.

Now write down the following lines in MainActivity.java file

Broad View Of Main Class

Read the below lines

First line is defining the URL of the Web service.

We will parse JSON using this URL via volley.

Second line is making the object of the progrss bar.

Third one is creating an arraylist with the objects of the DataModel class.

Fourth is making on object of RvAdapter and fifth is of RecyclerView class.

Inside onCreate() method, compiler is calling fetchingJSON() method.

Following is the code structure for fetchingJSON() method.

This method will parse the JSON and will populate the arraylist.

Json that it will parse is as the following

fetchingJSON() method will make an array (dataArray) using JSONArray class.

Then compiler will execute a for loop for the number of times equals to the number of items of the daraArray.

During every iteration, compiler will create one object of the DataModel class.

Then it will set the values using setter methods and finally, it will add the object into the arraylist (dataModelArrayList)

Then compiler will call the setupRecycler() method.

Code for setupRecycler() method is as the following

In this method, compiler will create the objects of the RvAdapter class.

It will use dataModelArrayList while making this object.

At last, this adapter is set to the recyclerview and it will create recyclerview from JSON data.

4. Android ListView Using Volley | Parse JSON Listview

Android ListView Using Volley is the important aspect in android development.

In this tutorial, you will learn to parse JSON Data with Volley and Display in ListView With Image and Text.

We will retrieve mysql data from web server in JSON format and will make custom listview with image and text using volley.

Volley is the library that simplifies the process of fetching json data from mysql server or database.

We are creating a demo where we will retrieve data like county, city, name and image URL in string format.

Making listview from this data will be easy task if we maintain data with proper model class structure.

Video Output

Step 1. Adding Gradle Dependencies

To use volley in android app, we need to fetch various classes of the library in our project.

We can do this by adding volley’s gradle dependency.

Add the below two lines in build.gradle(Module:app) file.

First line is the dependency for volley.

Second one is for Picasso library. We will use Picasso to load images from the URL.

Step 2. Permission To Use Internet

Internet is required to retrieve JSON data from remote server.

We have to write for Internet permission in AndroidManifest.xml file.

Copy the below line in AndroidManifest.xml

Asking for runtime permission is not required here because internet permission is a normal permission.

Step 3. Class of Model

To maintain the proper data structure for ListView, model class can be a perfect component.

We can define getter and setter methods in this class for all the information here.

Create a new class named DataModel.java and fill the below source code

There are different types of information like name, country, city and image URL in string format.

Above class includes separate getter and setter methods for all data types.

These methods will help to reduce complexity of listview adapter class.

Step 4. Proper ListView Layout

To make same layout for all the child of listview, we have to make one layout file.

Make a new Layout XML file under res->Layout directory.

Set the name of the file as lv_player.xml and copy the following code in it.

One ImageView and three TextView are representing the above file.

Image from URL will be loaded in the ImageView and other information will fill the textviews.

Step 5. ListView Adapter

Adapter works as the data setter for the ListView.

It helps us to set the data in each row with proper manipulation of the data.

Prepare a new java class and give it a name ListAdapter.java

Source code for ListAdapter.java is as the below

Understanding Adapter

Look at the below constructor

Adapter will get the arraylist (dataModelArrayList) made with the objects of DataModel via constructor.

This arraylist will help us to populate the listview.

Consider the following lines from getView() method.

First line will load the image from URL using Picasso.

Compiler will set this image in imageview.

Then it will set the other information in the respective textviews.

As you may have noticed that arraylist (dataModelArrayList) is giving us proper object with the help of position.

Step 6. Climax Changes

Now we just need to change the main files and that is all.

Set the code of activity_main.xml file as the below one

A textview in above snippet is suggesting that below listview is populated from json data.

Then a listview is present which holds the JSON data.

After this, source code for MainActivity.java is looking like the following

Entities of Main Activity

Let us check the modules of above class step by step.

Consider the below snippet

First line is representing the URL line from where we will get the JSON data.

Second one will create an object of progress dialog.

Third is giving us the object of Listview.

Fourth one is making an arraylist of the objects of the DataModel class.

Last one is making an Adapter object.

In onCreate() method, compiler will call a method retrieveJSON().

Code block of retrieveJSON() method is as the following

Compiler will show the progress dialog to inform user that system is fetching the data from the server.

Then it will use stringRequest class of volley with URL to make http call to server.

In the try block, we will parse the JSON using JSONObject and JOSNArray classes.

JSON fetched from the URL looks like the below

object named “status” will have true or false value.

If value is true then compiler will parse JSONArray called “data.”

One for loop is made up.

Number of iterations of for loop is equals to the number of object of “data” array.

During every iteration, compiler will set the data in the arraylist (dataModelArrayList).

After that, compiler will call setupListView() method.

Code for setupListView() method is as below

Compiler will first remove the progress dialog.

Then it will set the adapter to the listview. Adapter includes arraylist in it’s parameter.

Источник

Android volley get json

Использование библиотеки Volley в Android на примере получения данных из погодного API