Steps to create first app in android

How we create first app in Android

So Let’s we create a Simple project and show

“hello world”.....

Before creating a project  we have to discuss Project structure in android studio?

if we create a project or application  name is

HelloApplication(mainly it contains two folder)

Contain two folder

        ·   app

  · gradle script(it's not use for devloper )simple we can say it is for  studio purpose

So we discuss about app(mainly it consist three subfolder)

Contain three folder

·      java  (it contains all java files)

·      res  (Basically it is stand for Resource)

·      manifest(it consist one file that name is AndroidManifest.xml)

AndroidManifest.xml provide all infromation about your project means Activities,services,Permissions etc) Before installing application and before start an application android plateform read this file..

 So we discuss res folder(res stand for resource)

 res folder consist many subfolder  i show you here

Res folder

·      drawable  (it contains all images files which you

 want to add in your app)

·      layout  (it consist all layout files  (Ui Xml files)

·      values   (It consist all values files( .xml)

·      raw    (consists .mp4,.mp3,.txt,.pdf etc)

·      mipmap  (it contains icon of application)

·      anim   (it consist animation file (.xml)

menu   (it contains menus)

like this  I hope it's clear..........

so lets move next....

An android screen consist two files

·      Java(know as activity)

·      XML(it contains design part)

we explain here Xml File

it contains Ui Group and Ui Components) So a question arise here

              What is Ui Group

So we can say simply Ui group is like a container which Contains Ui Components.It also specify in what way Ui Components arranged

         here  we give Example of Ui Group

ü LinearLayout

It arrages Ui Components in a vertical or horizontal) I show you like this

         ü TableLayout
ü RelativeLayout

ü ConstraintLayout

                 üGridLayout

Ui   Components

Ui Components

·      TextView  (it used to display text on screen)

·      EditText  (it used to take inout from user)

·      Button   (it used to perfrom some action on click)

·      CheckBox

·      Radio

·      RadioGroup

·      ImageView   (It used to show images)

·      ImageButton

·      ToggleButton

·      FloatingActionButton

·      Switch

etc...

So i tell you how we can create a Xml File

Layout Xml file

a line is appear deafault which is optional

<?xml version="1.0" encoding="utf-8" ?>  this is known as prolog

then we have to specify Ui Group

I tell about LinearLayout

how we define

Ui group example

<LinearLayout

  xmlns:android="Xsd_location"

  android:layout_width="match_parent"

  android:layout_height="match_parent"

  andorid_orientation="vertical"

> 

///Ui Components

</LinearLayout>

here I tell which is  very important

Every Ui  Components and Ui Groups have two mandatory attributes width and height

Here I tell you Some Attributes values

match_parent  --it's take full space

wrap_content   -- it's take necessary space

dp    - specify the height and width of components or Ui groups

 sp   -scale pixels  (specify the size of text)

So second is that is Java file

How we can create it

Java File

package packge_name;

public class class_name extends AppCompactActivity

  {

  }

here is OnCreate() which is work a main funtion in c/c++ or like main method in java

the second is that

we have to link which design or layout we show on screen

so for this

We have to use one method that is

setContentView(R.layout.xml_file);

it's finish

Steps to create Hello world app

    ·      open you andorid studio

Note:--when you create your first application then you pc will have to connect with internet. 

so first screen appear like this

• Click on Start a new Android Studio Project

The a dialog box apeard as like this

• Then click on next

write here application name which must be in capital letters So let's wait android studio create project structure

• Then click on finish and wait upto Gradle sync finished

first we delete all code  so we start write code and write following code as shown in picture below.

• Save this code and go to  MainActivity file  and check layout xml file link or not

     

Here red box show layout xml connect with our activity..
for beginners it's fine....


so for run this app
Step-1
Open you android settings

Step-2
if developer option do not show . then search for build option

continuos click on Build number 7 times then automatically developer mode will open.

• click on Developer option and on usbdebugging mode.

then you can run you app on you real android.

• Here you can say you android name appear here and for run this application click on button 

Wait for untill gradle running finished
.........

when gradle running finished then output appear on you real device.

Then we finally create our first app in android studio.
i hope that you will understand easily.