Things to keep in res folder

  • images
  • text strings
  • screen layouts
  • styles
  • values
  • hexadecimal colors
  • dimensions

Android Manifest

  • Keeps informations of the app (eg, Activity, launcher action, permissions)

build.graddle(Module)

Contains configuration that are common for all modules

build.graddle(app)

Contains configuration for app module
eg. Changing sdk level, adding dependencies

Import XML designing notes:

Properties

layout_width or layout_height:

  • match_parent: Matches with the size of its parent
  • wrap_content: Fit the size to its content
  • 10dp (xdp): Set a specific density independent pixel (adjusted to screen density)

Gravity:

android:layout_graivity
  • center_horizontal: Center itself horizontally
  • center_vertical: Center itself vertically

Important Text properties

android:textSize

  • 10sp (xsp): set specific scalable pixel (adjusted to screen density and user text size preference)

Enable Vector drawable for api level under 21

Go to your build.graddle(Module: app) file and add this line to your defaultConfig

vectorDrawables.useSupportLibrary = true

Layout Design guideline:

Margin left/start and Margin right/end

From android api 17 the paddingLeft, layout_marginLeft is changed to paddingStart, layout_marginStart
but when we also want to make the style compitable with api level 16 or lower versions we need to use both attributes
For example, use both android:paddingLeft and android:paddingStart.

Scroll view help

Always give id to ScrollView.It gives the Android system a handle for the view so that when the user rotates the device, the system preserves the scroll position.

String Resource note

  • we can use \n to insert line break
  • we can use To make a text bold
  • we can use to make a text italic
  • apostrophe has to be escaped with backslash

Constraint Layout

  • Allows to position and size childs in a flexible way
  • Each view needs atleast on horizonatal and one vertical constraints
  • Flatter in view hirerchy

###

  • A group of views that are linked with one another
  • vertically or horizontally
  • packed, spread, weighted

Baseline Constraints

  • Set constraint for text base line
  • Helpful when texts are of different sizes

Data Binding

  • to make code shorter, easier to read, easier to maintain
  • the android system traverses the view hierarchy once to get each view at app startup not at runtime when user is interacting with the app

  • to enable data binding add this into your build.gradle(Module: app) file:

      buildFeatures {
      dataBinding true

  }
  • to work with databinding we need to wrap our xml layout with a <layout> tag. and also move the namespace declaration to layout tag
  • create a variable name binding
  • relplace set content view with
  • I created a data class and link view to data by using variable tag inside data tag of xml file

Fragment

  • A Fragment has its own lifecycle and receives its own input events.
  • You can add or remove a Fragment while the activity is running.
  • A Fragment is defined in a Kotlin class.
  • A Fragment’s UI is defined in an XML layout file.

Sensor Manager getting

Getting Sensor Manager

getSystemService(Context.SENSOR_SERVICE) as SensorManager

Getting All Type of Sensor List

val sensorList = mSensorManager.getSensorList(Sensor.TYPE_ALL)

To get a sensor name we can access getName() method or name property