Login forms in android

Android — Login Screen

A login application is the screen asking your credentials to login to some particular application. You might have seen it when logging into facebook,twitter e.t.c

This chapter explains, how to create a login screen and how to manage security when false attempts are made.

First you have to define two TextView asking username and password of the user. The password TextView must have inputType set to password. Its syntax is given below −

Define a button with login text and set its onClick Property. After that define the function mentioned in the onClick property in the java file.

In the java file, inside the method of onClick get the username and passwords text using getText() and toString() method and match it with the text using equals() function.

The last thing you need to do is to provide a security mechanism, so that unwanted attempts should be avoided. For this initialize a variable and on each false attempt, decrement it. And when it reaches to 0, disable the login button.

Example

Here is an example demonstrating a login application. It creates a basic application that gives you only three attempts to login to an application.

To experiment with this example, you can run this on an actual device or in an emulator.

Steps	Description
1	You will use Android studio to create an Android application under a package com.example.sairamkrishna.myapplication.
3	Modify src/MainActivity.java file to add necessary code.
4	Modify the res/layout/activity_main to add respective XML components
5	Run the application and choose a running android device and install the application on it and verify the results

Following is the content of the modified main activity file src/MainActivity.java.

Following is the modified content of the xml res/layout/activity_main.xml.

In the following code abc indicates about logo of tutorialspoint.com

Following is the content of the res/values/string.xml.

Following is the content of AndroidManifest.xml file.

Let’s try to run our application we just modified. I assume you had created your AVD while doing environment setup. To run the app from Android studio, open one of your project’s activity files and click Run icon from the toolbar. Android studio installs the app on your AVD and starts it and if everything is fine with your setup and application, it will display following Emulator window −

Type anything in the username and password field, and then press the login button. I put abc in the username field and abc in the password field. I got failed attempt. This is shown below −

Do this two more time, and you will see that you have 0 login attempts left and your login button is disabled.

Now open the application again, and this time enter correct username as admin and password as admin and click on login. You will be successfully login.

If user press on cancel button, it will close an application of login screen.

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How to Create User Interface Login & Register with Android Studio

ok, this is my first article in Medium. In this section, I want to share with you about the User Interface on Android and we will create a Login page and a Register page. Some components that I will use:
1. Viewpager
2. Fragment
3. Edittext
4. Button
5. Textview
6. Imageview

What about the results? let’s coding (follow step by step)

1. Of course we must already have an Android Studio. if not, you can download it first on the official Android Studio website. If you already have one, please open your Android studio.

2. We create a new project by clicking “Start a new Android Studio project”. Fill in the application name column with “LoginApp”, then click next.

3. Select the minimum SDK you need or want, then click next.

4. Select “Empty Activity” and click next. After that, the “Activity Name” and “Layout Name” columns will appear, in this section just leave it like that, then click finish.

After you click finish, Android Studio will make you an Application with the name “LoginApp”.

After the application is successfully built, you can simply make adjustments to the following sections:

Open the colors.xml file in app/res/values/colors.xml, and change it like this:

Create a folder with the name “font” in the res folder, by right clicking on the res directory, select new / directory and name it “font”. After that, copy this font into font directory. (download the font 1 and font 2).

Create some Drawable Resource File in the drawable directory, by right-clicking on the drawable directory, select new / Drawable Resource File.

After that open file styles.xml and change like this :

Add the theme property in the Main Activity in the manifest, in the app / manifests / AndroidManifest.xml folder

So the AndroidManifest.xml file will be as follows:

After all the steps above are done, then make 2 fragments with the name fragment_login and fragment_register in the layout directory, by right-clicking on the layout directory, New/Fragment/Fragment (Blank)

Uncheck:
include fragment factory methods? and include interface methods?

Adjustment of several layouts :

change the activity_main.xml layout, fragment_login.xml and fragment_register.xml so that it will be as below

Open the strings.xml file in the res / values / strings.xml directory and change it to something like the following :

So that the overall structure of the project will be as follows :

Connect fragments with viewpager

Create an inner class in the MainActivity.java class with the name AuthenticationPapterAdapter. This class is a derivative of the FragmentPagerAdapter class and serves to connect Fragments with ViewPager,

Then call the class in the onCreate() method in MainActivity.java and connect with viewpager

So the MainActivity.java class will be like this

The display of the final application will be like this

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Login forms in android

Android Login Form in Java

Simple login form in Java only

Keep in mind that it is mainly for APK modding and not for general app development purposes

okhttp dependency is no longer required, we use URL instead. You can still use okhttp if you want, uncomment the okhttp codes related

Note: This project is for experienced modders and programmers only and you must be able to do yourself and be able to search for help. This project will not be maintained much, we will NOT offer help and support with this project, and the Example will not be updated.

Add login.php to your server that supports PHP, use 000webhost.com for free webserver. Repo based hosting such as Github does not support PHP

Change URL on public static String URL on MainActivity.java file

Merging into your project

It’s easy, just copy and paste the code of public static void Start(final Context context) into your project and make some changes

See the example folder how the login code was merged into the mod menu project on MainActivity.java file

How to implement to APK:

Build the project to APK file.

Build -> Build Bundle(s)/APK(s) -> Build APK(s)

If no errors occured, you did everything right and build will succeded. You will be notified that it build successfully

Click on locate to show you the location of build.apk. It is stored at (your-project)\app\build\outputs\apk\app-debug.apk

Now decompile your app-debug.apk.

Copy all your smali folders to the game’s smali folder to the game’s decompiled directory (game name)\smali . If the game have multidexes, add your smali to the last classes dex if possible to prevent compilation errors such as Unsigned short value out of range: xxxxx

If the game has already okhttp smalis, don’t add it.

Now, you must know the game’s launch activity/main activity

You can either use APK Easy Tool to view main activity like screenshot below:

Or decompile your game APK using apktool.jar, or any 3rd party CLI or GUI tools, and open androidmanifest.xml and search after

In this case, my game’s main activity was com.unity3d.player.UnityPlayerActivity

On the game’s androidmanifest.xml , besure that exist

Locate to the game’s path of main activity and open the smali file.

Example if it was com.unity3d.player.UnityPlayerActivity , the path would be (decompiled game)/com/unity3d/player/UnityPlayerActivity.smali

If the game have multi dexes, it may be located in smali_classes2. please check all

Open the main acitivity’s smali file, search for OnCreate method and paste this code inside (change the package name if you had changed it)

Now compile the game APK

It should launch the login screen and successfully launch the activity after login 🙂

Simple protection in lib

See native-lib.cpp for example how to check if the user has logged in

There are the codes called Check() and System.loadLibrary(«yourlib»); . They are commented out

You may need to protect your dex and lib files for that

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Android Login and Register with SQLite Database Tutorial

In software applications, it is mostly required to store users and app data locally. Android SDK provides several APIs for developers to save user and app data, So SQLite is one of the ways of storing data. For many applications, SQLite is the backbone of the app whether it’s used directly or via some third-party wrapper. In this tutorial, we will see how to use SQLite in our app directly.

What is SQLite?

SQLite is a lightweight database that comes with android. It is an Open-Source embedded SQL database engine. This provides a relational database management structure for storing user-defined records in the form of tables.

Key point to understand regarding SQLite :-

– SQLite is a RDBMS (Relational Database Management System)
– SQLite is written in C programming language
– SQLite is embedded within the Android operating system, so you don’t need anything external on Android to use SQLite
– To manipulate data (insert, update, delete) in SQLite database – we’ll use SQL (Structured Query Language)

Let’s Get it Working

In this tutorial we are going to learn how to use SQLite. To really understand the usage of SQLite we will create an app . The App contains simple Login form, Registration form and listing of registered user. This app shows how SQLite database operations are performed. I assume that you have created a new android project. Source Code is available on GitHub.

Step 1) Update build.gradle file.

Before you can use Material Design in your projects you need to add the following compile line to your Gradle dependencies block in your build.gradle file and rebuilt the project .

Step 2) Update strings.xml.

Add the below string values to the string.xml located in res => values => strings.xml.

Step 3) Update colors.xml.

Add the below color values to the colors.xml located in res => values => colors.xml.

Step 4) Update styles.xml.

Add the below style values to the styles.xml located in res => values => styles.xml.

Step 5) Add Logo Image.

Download the below logo image and add it to the drawable folder located in res => drawable.

Android Tutorials Hub Logo

Step 6) Create a User model class.

Create a new package named modal and create a User class with all getter and setter methods to maintain single contact as an object.

Step 7) Create a DatabaseHelper class.

Create a new package named SQL and create a DatabaseHelper class. Extend this class with SQLiteOpenHelper to manage database creation and version management. I have also written some methods to manipulate data in the database.

Methods and functionality

– addUser :- add a user to the database.
– getAllUser :- fetch users data from the database.
– updateUser :- update the user in the database on the basis of the user id.
– deleteUser :- delete user from the database on the basis of the user id.
– checkUser :- check whether the user exists in the database.

User Table Schema

Step 8) Create activity_login.xml.

Now create a layout file for the LoginActivity.java i.e activity_login.xml and add the below code in your layout file. The code will create a simple login form containing logo on the top, 2 input fields email and password, login button, and registration screen navigation link.

activity_login.xml would result in a screen like this:

Step 8) Create InputValidation class.

Create a package named helpers and create a class in it named InputValidation.java and add below code in it. The code will create validation methods for the input field. Validation like empty input, valid email and etc.

Step 9) Create a LoginActivity class.

Now create a package named activities and create a class named LoginActivity and add below code. Here i have written the code to validate the input fields Email and Password using the InputValidation class which I described above. Also, code for navigation to registration screen on the click of registration link and to user list screen after clicking on the login button if credentials are valid.

The Screen below shows the login form with input validation display the error message if values entered in input fields are not valid.

Login Screen with Input Validation

The Screen below shows the login form with input validation display the snack bar with a message if values entered in input fields are not validated from the SQLite database.

Login Screen With SQLite Validation

Step 10) Create activity_register.xml.

Now create a layout file for the RegisterActivity.java i.e activity_register.xml and add the below code in your layout file. The code will create a simple registration form containing a logo on the top, 4 input fields name, email, password, and confirm password, register button, and login screen navigation link.

activity_register.xml would result in a screen like this:

Step 11) Create RegisterActivity class.

Now create a package named activities and create a class named RegisterActivity and add below code. Here I have written the code to validate the input fields Name, Email, Password, and Confirm Password using the InputValidation class which I described above. Also, code for navigation to the login screen on the click of login link and shows snackbar with success message for registration.

The Screen below shows the registration form with input validation display the error message if values entered in input fields are not valid.

Register Screen with Input Validation

The Screen below shows the filled registration form with valid values.

Register Screen with filled input fields

The Screen below shows the register form display the snackbar with the registration success message.

Register Screen with Registration Success Message

Step 12) Create activity_users_list.xml.

Now create a layout file for the UsersListActivity.java i.e activity_users_list.xml and add the below code in your layout file. The code will create a simple view containing two views one view i.e LinearLayout shows the welcome message with email id of the logged in user and another view i.e RecyclerView shows the list of registered users in the app.

activity_users_list.xml would result in a screen like this:

User List Screen

Step 13) Writing the Adapter Class.

Now create a package named adapters and create a class named UsersRecyclerAdapter and add below code. Here onCreateViewHolder() method inflates item_user_recycler.xml. In onBindViewHolder() method the appropriate User data (name, email, and password) set to each row.

item_user_recycler.xml

Step 14) Create UsersListActivity class.

Now create a package named activities and create a class named UsersListActivity and add below code. Here i have written the code to show the email id of the logged in user and the list of registered users.

The Screen below after user login shows the brand name, email id of logged in user, and registered users list.

User List Screen After Login

Step 15) Update AndroidManifest.xml.

To learn this tutorial using KOTLIN Language Click here.

Please feel free to comment as well as ask questions. And, yeah! If this post helps you please do share!

Enjoy Coding and Share Knowledge

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