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What is Android?

Android is an open source and Linux-based Operating System for mobile devices such as

smartphones and tablet computers. Android was developed by the Open Handset Alliance, led by

Google, and other companies.

Android offers a unified approach to application development for mobile devices which means

developers need only develop for Android, and their applications should be able to run on

different devices powered by Android.

The first beta version of the Android Software Development Kit (SDK) was released by Google

in 2007 where as the first commercial version, Android 1.0, was released in September 2008.

Android Applications

Android applications are usually developed in the Java language using the Android Software

Development Kit.

Once developed, Android applications can be packaged easily and sold out either through a

store such as Google Play, SlideME, Opera Mobile Store, Mobango, F-droid and

the Amazon Appstore.

Categories of Android applications

There are many android applications in the market. The top categories are listed below :

History of Android

The code names of android ranges from A to N currently, such as Aestro, Blender, Cupcake,

Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwitch, Jelly Bean, KitKat,

Lollipop and Marshmallow. Let's understand the android history in a sequence.

The latest version is Android 7 Nougat

Step 1 - System Requirements :

You will be delighted, to know that you can start your Android application development on

either of the following operating systems −

Microsoft® Windows® 10/8/7/Vista/2003 (32 or 64-bit)

Mac® OS X® 10.8.5 or higher, up to 10.9 (Mavericks)

GNOME or KDE desktop

Second point is that all the required tools to develop Android applications are open source and

can be downloaded from the Web. Following is the list of software's you will need before you

start your Android application programming.

Java JDK5 or later version

Java Runtime Environment (JRE) 6

Android Studio

Step 2 - Setup Android Studio

Android Studio is the official IDE for android application development. It works based

on IntelliJ IDEA, You can download the latest version of android studio from Android Studio

2.2 Download, If you are new to installing Android Studio on windows, you will find a file,

which is named as android-studio-bundle-143.3101438-windows.exe.So just download and run

on windows machine according to android studio wizard guideline.

https://developer.android.com/sdk/index.html

https://developer.android.com/sdk/index.html

If you are installing Android Studio on Mac or Linux, You can download the latest version

from Android Studio Mac Download,or Android Studio Linux Download, check the

instructions provided along with the downloaded file for Mac OS and Linux. This tutorial will

consider that you are going to setup your environment on Windows machine having Windows

8.1 operating system.

Installation

So let's launch Android Studio.exe, Make sure before launch Android Studio, Our Machine

should require installed Java JDK. To install Java JDK, take a reference of Android

environment setup

Once you launched Android Studio, it’s time to mention JDK7 path or later version in android

studio installer.

https://dl.google.com/dl/android/studio/install/1.1.0/android-studio-ide-135.1740770-mac.dmg

https://dl.google.com/dl/android/studio/ide-zips/1.1.0/android-studio-ide-135.1740770-linux.zip

https://www.tutorialspoint.com/android/android_environment_setup.htm

https://www.tutorialspoint.com/android/android_environment_setup.htm

Below the image initiating JDK to android SDK

Need to check the components, which are required to create applications, below the image has

selected Android Studio, Android SDK, Android Virtual Machine and performance (Intel

chip).

Need to specify the location of local machine path for Android studio and Android SDK, below

the image has taken default location of windows 8.1 x64 bit architecture.

Need to specify the ram space for Android emulator by default it would take 512MB of local

machine RAM.

At final stage, it would extract SDK packages into our local machine, it would take a while time

to finish the task and would take 2626MB of Hard disk space.

After done all above steps perfectly, you must get finish button and it open android studio

project with Welcome to android studio message as shown below

You can start your application development by calling start a new android studio project. in a

new installation frame should ask Application name, package information and location of the

project.

After entered application name, it going to be called select the form factors your application

runs on, here need to specify Minimum SDK, in our tutorial, I have declared as API23: Android

6.0(Mashmallow)

The next level of installation should contain selecting the activity to mobile, it specifies the

default layout for Applications

At the final stage it going to be open development tool to write the application code.

Step 3 - Create Android Virtual Device

To test your Android applications, you will need a virtual Android device. So before we start

writing our code, let us create an Android virtual device. Launch Android AVD Manager

Clicking AVD_Manager icon as shown below

After Click on a virtual device icon, it going to be shown by default virtual devices which are

present on your SDK, or else need to create a virtual device by clicking Create new Virtual

device button

If your AVD is created successfully it means your environment is ready for Android application

development. If you like, you can close this window using top-right cross button. Better you re-

start your machine and once you are done with this last step, you are ready to proceed for your

first Android example but before that we will see few more important concepts related to

Android Application Development.

Anatomy of Android Application

Before you run your app, you should be aware of a few directories and files in the Android

project −

Sr.No. Folder, File & Description

1

Java

This contains the .java source files for your project. By default, it includes

an MainActivity.java source file having an activity class that runs when your

app is launched using the app icon.

2

res/drawable-hdpi

This is a directory for drawable objects that are designed for high-density

screens.

3

res/layout

This is a directory for files that define your app's user interface.

4

res/values

This is a directory for other various XML files that contain a collection of

resources, such as strings and colours definitions.

5

AndroidManifest.xml

This is the manifest file which describes the fundamental characteristics of the

app and defines each of its components.

6

Build.gradle

This is an auto generated file which contains compileSdkVersion,

buildToolsVersion, applicationId, minSdkVersion, targetSdkVersion,

versionCode and versionName

Following section will give a brief overview few of the important application files.

The Main Activity File

The main activity code is a Java file MainActivity.java. This is the actual application file

which ultimately gets converted to a Dalvik executable and runs your application. Following is

the default code generated by the application wizard for Hello World! application −

package com.example.helloworld;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

}

}

Here, R.layout.activity_main refers to the activity_main.xml file located in the res/layout folder.

The onCreate() method is one of many methods that are figured when an activity is loaded.

The Manifest File

Whatever component you develop as a part of your application, you must declare all its

components in a manifest.xml which resides at the root of the application project directory. This

file works as an interface between Android OS and your application, so if you do not declare

your component in this file, then it will not be considered by the OS. For example, a default

manifest file will look like as following file −

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

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

package="com.example.tutorialspoint7.myapplication">

<application

android:allowBackup="true"

android:icon="@mipmap/ic_launcher"

android:label="@string/app_name"

android:supportsRtl="true"

android:theme="@style/AppTheme">

<activity android:name=".MainActivity">

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

</application>

</manifest>

Here <application>...</application> tags enclosed the components related to the application.

Attribute android:icon will point to the application icon available under res/drawable-hdpi. The

application uses the image named ic_launcher.png located in the drawable folders

The <activity> tag is used to specify an activity and android:name attribute specifies the fully

qualified class name of the Activity subclass and the android:label attributes specifies a string to

use as the label for the activity. You can specify multiple activities using <activity> tags.

The action for the intent filter is named android.intent.action.MAIN to indicate that this activity

serves as the entry point for the application. The category for the intent-filter is

named android.intent.category.LAUNCHER to indicate that the application can be launched

from the device's launcher icon.

The @string refers to the strings.xml file explained below. Hence, @string/app_name refers to

the app_name string defined in the strings.xml file, which is "HelloWorld". Similar way, other

strings get populated in the application.

Following is the list of tags which you will use in your manifest file to specify different Android

application components −

<activity>elements for activities

<service> elements for services

<receiver> elements for broadcast receivers

<provider> elements for content providers

The Strings File

The strings.xml file is located in the res/values folder and it contains all the text that your

application uses. For example, the names of buttons, labels, default text, and similar types of

strings go into this file. This file is responsible for their textual content. For example, a default

strings file will look like as following file −

<resources>

<string name="app_name">HelloWorld</string>

<string name="hello_world">Hello world!</string>

<string name="menu_settings">Settings</string>

<string name="title_activity_main">MainActivity</string>

</resources>

The Layout File

The activity_main.xml is a layout file available in res/layout directory, that is referenced by

your application when building its interface. You will modify this file very frequently to change

the layout of your application. For your "Hello World!" application, this file will have following

content related to default layout −

<RelativeLayout 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" >

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_centerVertical="true"

android:padding="@dimen/padding_medium"

android:text="@string/hello_world"

tools:context=".MainActivity" />

</RelativeLayout>

This is an example of simple RelativeLayout which we will study in a separate chapter.

The TextView is an Android control used to build the GUI and it have various attributes

like android:layout_width, android:layout_height etc which are being used to set its width and

height etc.. The @string refers to the strings.xml file located in the res/values folder. Hence,

@string/hello_world refers to the hello string defined in the strings.xml file, which is "Hello

World!".

Running the Application

Let's try to run our Hello World! application we just created. I assume you had created

your AVD while doing environment set-up. To run the app from Android studio, open one of

your project's activity files and click Run icon from the tool bar. Android studio installs the

app on your AVD and starts it and if everything is fine with your set-up and application, it will

display following Emulator window −

Congratulations!!! you have developed your first Android Application and now just keep

following rest of the tutorial step by step to become a great Android Developer. All the very

best.

Sample Example with code :

1. Addition of two numbers and Navigating to next screen.

Java file

package com.example.babu.myapp1;

import android.content.Intent;



import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

@Override




TextView t1=(TextView)findViewById(R.id.t1);

TextView t2=(TextView)findViewById(R.id.t2);

final TextView t3=(TextView)findViewById(R.id.t3);

final EditText e1=(EditText)findViewById(R.id.e1);


Button b1=(Button)findViewById(R.id.b1);


b2.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Intent i=new Intent(MainActivity.this, MyActivity2.class );

startActivity(i);

}

});


@Override


int a=Integer.parseInt(e1.getText().toString());

int b=Integer.parseInt(e2.getText().toString());

int c =a+b;

t3.setText(Integer.toString(c));

}

});

}

}

Xml file


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



android:layout_height="match_parent"

android:paddingBottom="@dimen/activity_vertical_margin"

android:paddingLeft="@dimen/activity_horizontal_margin"

android:paddingRight="@dimen/activity_horizontal_margin"

android:paddingTop="@dimen/activity_vertical_margin"

android:orientation="vertical"

tools:context="com.example.babu.myapp1.MainActivity">

<TextView



android:text="welcome to Android Class" />

<TextView

android:id="@+id/t1"

android:text="Enter First number"


android:layout_height="wrap_content" />

<EditText

android:id="@+id/e1"



<TextView


android:text="Enter second number"



<EditText

android:id="@+id/e2"



<Button

android:id="@+id/b1"

android:text="add"



<TextView




<Button

android:text="click next screen"

android:id="@+id/b2"



</LinearLayout>

2.Styles

Xml file.


<RelativeLayout

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








tools:context=".MainActivity">

<TextView

android:id="@+id/textView2"



android:text="Android Workshop Styles "

android:textColor="#ff87ff09"

android:textSize="30dp"

android:layout_above="@+id/imageButton"


android:layout_marginBottom="40dp" />

<ImageButton



android:id="@+id/imageButton"

android:src="@drawable/ic_launcher"

android:layout_centerVertical="true"

android:layout_centerHorizontal="true" />

<Button



android:text="Small font"

android:id="@+id/button"

android:layout_below="@+id/imageButton"

android:layout_centerHorizontal="true" />

<Button



android:text="Large Font"

android:id="@+id/button2"

android:layout_below="@+id/button"

android:layout_alignRight="@+id/button"

android:layout_alignEnd="@+id/button" />

<TextView



android:text="Hello World!"

android:id="@+id/textView"

android:layout_below="@+id/button2"


android:textSize="25dp" />

</RelativeLayout>

Java file

package com.example.babu.workshop2;

import android.app.ProgressDialog;


import android.support.v7.app.ActionBarActivity;



import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

private ProgressDialog progress;

Button b1,b2;

@Override




progress = new ProgressDialog(this);

b1=(Button)findViewById(R.id.button);

b2=(Button)findViewById(R.id.button2);


@Override


TextView txtView = (TextView) findViewById(R.id.textView);

txtView.setTextSize(10);

}

});


@Override


TextView txtView = (TextView) findViewById(R.id.textView);

txtView.setTextSize(55);

}

});

}

}

3.

Registration and Login application

Xml files

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


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









app:layout_behavior="@string/appbar_scrolling_view_behavior"

tools:context="com.example.babu.worshopregistration2.MainActivity"

tools:showIn="@layout/activity_main">

<TextView



android:text="HOME PAGE" />

<Button



android:text="REGISTRATION"

android:id="@+id/b1"/>

<Button



android:text="LOGIN"


</LinearLayout>

2. <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"











tools:context="com.example.babu.worshopregistration2.Registration"

tools:showIn="@layout/activity_registration">

<TextView



android:text="THIS IS REGISTRATION PAGE"/>

<TextView



android:text="NAME "/>

<EditText



android:id="@+id/e1"/>

<TextView



android:text="PASSWORD "/>

<EditText




<TextView



android:text="EMAIL "/>

<EditText




<TextView



android:text="PHONE_NO "/>

<EditText




<Button



android:text="SUBMIT"

android:id="@+id/b1" />

</LinearLayout>

3.













tools:context="com.example.babu.worshopregistration2.Login"

tools:showIn="@layout/activity_login">

<TextView



android:text="NAME"/>

<EditText




<TextView



android:text="PASSWORD"/>

<EditText




<Button



android:text="OK"


</LinearLayout>

Java files

1.registration

package com.example.babu.worshopregistration2;


import android.database.sqlite.SQLiteDatabase;


import android.support.design.widget.FloatingActionButton;

import android.support.design.widget.Snackbar;


import android.support.v7.widget.Toolbar;




public class Registration extends AppCompatActivity {

SQLiteDatabase sd=null;

@Override



setContentView(R.layout.activity_registration);

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

setSupportActionBar(toolbar);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

fab.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

Snackbar.make(view, "Replace with your own action",

Snackbar.LENGTH_LONG)

.setAction("Action", null).show();

}

});






sd=openOrCreateDatabase("user",MODE_PRIVATE,null);

sd.execSQL("create table if not exists login(name varchar, password varchar,email

varchar, phone varchar)");


@Override


String name=e1.getText().toString();

String password=e2.getText().toString();

String email=e3.getText().toString();

String phone=e4.getText().toString();

sd.execSQL("insert into login

values('"+name+"','"+password+"','"+email+"','"+phone+"')");

Intent i=new Intent(Registration.this,welcome.class);

startActivity(i);

sd.close();

finish();

}

});

}

}

2. login

package com.example.babu.worshopregistration2;


import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;


import android.support.design.widget.FloatingActionButton;

import android.support.design.widget.Snackbar;


import android.support.v7.widget.Toolbar;




import android.widget.Toast;

public class Login extends AppCompatActivity {

SQLiteDatabase sd;

@Override



setContentView(R.layout.activity_login);

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

setSupportActionBar(toolbar);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

fab.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

Snackbar.make(view, "Replace with your own action",

Snackbar.LENGTH_LONG)

.setAction("Action", null).show();

}

});





@Override


String name=e1.getText().toString();

String password=e2.getText().toString();

sd=openOrCreateDatabase("user",MODE_PRIVATE,null);

Cursor c=sd.rawQuery("select * from login where name='"+name+"' and

password='"+password+"'",null) ;

c.moveToNext();

if(c.getCount()>0)

{

Intent i=new Intent(Login.this,welcome.class);

startActivity(i);

sd.close();

finish();

}

else

Toast.makeText(Login.this, "Wrong user name and wrong

password",Toast.LENGTH_SHORT).show();

}

});

}

}

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