JCB - Scaffold FloatingActionButton

val sheetState = rememberModalBottomSheetState(
    initialValue = ModalBottomSheetValue.Hidden,
    confirmStateChange = { it != ModalBottomSheetValue.HalfExpanded }
)

/**
 * Used as a wrapper for data that is exposed via a LiveData that represents an event.
 */
open class Event<out T>(private val content: T) {

    var hasBeenHandled = false
        private set // Allow external read but not write

    /**
     * Returns the content and prevents its use again.
     */
    fun getContentIfNotHandled(): T? {
        return if (hasBeenHandled) {
            null
        } else {
            hasBeenHandled = true
            content
        }
    }

    /**
     * Returns the content, even if it's already been handled. */ fun peekContent(): T = content }Copy the code

@Preview(device = Devices.PIXEL_3A)
@Composable
fun ExamplePreview() {...}

@Preview(uiMode = UI_MODE_NIGHT_NO)
@Preview(uiMode = UI_MODE_NIGHT_YES)
@Composable
fun ExamplePreview() {...}

@Preview(showBackground = true, backgroundColor = 0xff0000)
@Composable
fun ExamplePreview() {...}

@Preview
@Preview(locale = "fr")
@Composable
fun ButtonPreview() {
  Button(
    ...
    content = { Text(text = stringResource(id = R.string.day_monday)) })
}

@Preview(widthDp = 100, heightDp = 100)
@Composable
fun ExamplePreview() {...}

@Preview(group = "Buttons")
@Composable
fun ButtonEnabledPreview() {...}

@Preview(group = "Buttons")
@Composable
fun ButtonDisabledPreview() {...}

@Preview(group = "Texts")
@Composable
fun TextBigPreview() {...}

@Preview(group = "Texts")
@Composable
fun TextSmallPreview() {...}

@Preview(name = "Some preview name")
@Composable
fun ExamplePreview() {
  ...
}

val name: String = "",
val group: String = "",
@IntRange(from = 1) val apiLevel: Int = -1,
val widthDp: Int = -1,
val heightDp: Int = -1,
val locale: String = "",
@FloatRange(from = 0.01) val fontScale: Float = 1f,
val showSystemUi: Boolean = false,
val showBackground: Boolean = false,
val backgroundColor: Long = 0,
@UiMode val uiMode: Int = 0,
@Device val device: String = Devices.DEFAULT

@Preview
@Composable
fun ExamplePreview() {
  Button(
    modifier = Modifier.fillMaxWidth(),
    onClick = {},
    content = { Text(text = "Button") })
}

import kotlin.math.abs

const val riesenieSila = 92
const val riesenieSmer = 15

data class Riesenie(val sila: Int, val smer: Int) {
    fun cost() : Int =
        abs(riesenieSila - sila) +
        abs(riesenieSmer - smer)
}

fun main() {
    // vytvorenie nahodneho riesenia
    var riesenie = Riesenie(50, 60)
    while(true) {
        // ziskanie susednych rieseni
        val noveRiesenia = arrayOf(
            Riesenie(riesenie.sila - 1, riesenie.smer),
            Riesenie(riesenie.sila + 1, riesenie.smer),
            Riesenie(riesenie.sila, riesenie.smer - 1),
            Riesenie(riesenie.sila, riesenie.smer + 1)
        )
        val najlepsieNoveRiesenie = noveRiesenia.minByOrNull{ it.cost() }!!

        // vyhodnotenie
        if (najlepsieNoveRiesenie.cost() > riesenie.cost()) { break }
        else { riesenie = najlepsieNoveRiesenie }
    }

    println("najlepsie riesenie - ${riesenie.sila} / ${riesenie.smer}")
}

package com.example.addressbook

import android.content.Intent
import android.os.Bundle
import android.os.Handler
import androidx.appcompat.app.AppCompatActivity

class SplashScreen : AppCompatActivity() {
    private lateinit var runnable:Runnable
    private val handler = Handler()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_splash)

        runnable = Runnable {
            val intent = Intent(this,MainActivity::class.java)
            startActivity(intent)
            finish()
        }

        handler.postDelayed(runnable,10000)
    }

    override fun onDestroy() {
        handler.removeCallbacks(runnable)
        super.onDestroy()

        //Toast.makeText(this,"onDestroy called",Toast.LENGTH_SHORT).show()
    }
    fun startNextActivity() {
        startActivity(Intent(applicationContext, MainActivity::class.java))
    }

    fun skipSplashScreen() {
        if (handler != null) handler.removeCallbacksAndMessages(null)
        startNextActivity()
    }

    override fun onStop() {
        super.onStop()
        // clear handler on stop
        if (handler != null) handler.removeCallbacksAndMessages(null)
    }
}

<resources>
    <string name="app_name">Implicit Intent Example</string>
    <string name="phone_number">Phone Number</string>
    <string name="call">Call</string>
    <string name="call_logs">Call Logs</string>
    <string name="contact">Contact</string>
    <string name="web_browser">Web Browser</string>
    <string name="gallery">Gallery</string>
    <string name="camera">Camera</string>
    <string name="alarm">Alarm</string>
</resources>

----
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:isScrollContainer="true">

    <EditText
        android:id="@+id/et_number"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:hint="@string/phone_number"
        android:inputType="number"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btn_call"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/call"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/et_number" />

    <Button
        android:id="@+id/btn_call_log"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/call_logs"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_call" />

    <Button
        android:id="@+id/btn_contact"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/contact"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_call_log" />

    <Button
        android:id="@+id/btn_browser"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/web_browser"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_contact" />

    <Button
        android:id="@+id/btn_gallery"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/gallery"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_browser" />

    <Button
        android:id="@+id/btn_camera"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/camera"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_gallery" />

    <Button
        android:id="@+id/btn_alarm"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/alarm"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_camera" />
</android.support.constraint.ConstraintLayout>

---
          import android.Manifest
import android.annotation.SuppressLint
import android.content.Intent
import android.content.pm.PackageManager
import android.net.Uri
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.provider.AlarmClock
import android.provider.CallLog
import android.provider.CallLog.*
import android.provider.ContactsContract
import android.provider.MediaStore
import android.support.v4.app.ActivityCompat
import android.support.v4.content.ContextCompat
import android.util.Log
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    val CALL_REQUEST_CODE = 101

    @SuppressLint("MissingPermission")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        setupPermissions()

        // Calling using intent
        btn_call.setOnClickListener(View.OnClickListener {
            val intent = Intent(Intent.ACTION_CALL)
            intent.data = Uri.parse("tel:" + et_number.getText())
            startActivity(intent)
        })

        // Call log
        btn_call_log.setOnClickListener(View.OnClickListener {
            val intent = Intent(Intent.ACTION_VIEW)
            intent.type = Calls.CONTENT_TYPE
            startActivity(intent)
        })

        //Contact
        btn_contact.setOnClickListener(View.OnClickListener {
            val intent = Intent(Intent.ACTION_PICK)
            intent.type = ContactsContract.Contacts.CONTENT_TYPE
            startActivity(intent)
        })

        // browser
        btn_browser.setOnClickListener(View.OnClickListener {
            val intent = Intent(Intent.ACTION_VIEW)
            intent.data = Uri.parse("https://tutorial.eyehunts.com/")
            startActivity(intent)
        })

        // Gallery
        btn_gallery.setOnClickListener(View.OnClickListener {
            val intent = Intent(Intent.ACTION_VIEW)
            intent.data = Uri.parse("content://media/external/images/media/")
            startActivity(intent)
        })

        // camera
        btn_camera.setOnClickListener(View.OnClickListener {
            val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
            startActivity(intent)
        })

        // alarm
        btn_alarm.setOnClickListener(View.OnClickListener {
            val intent = Intent(AlarmClock.ACTION_SHOW_ALARMS)
            startActivity(intent)
        })
    }

    private fun setupPermissions() {
        val permission = ContextCompat.checkSelfPermission(this,
                Manifest.permission.CALL_PHONE)

        if (permission != PackageManager.PERMISSION_GRANTED) {
            Log.i("noone", "Permission to Call has denied")
            makeRequest()
        }
    }

    private fun makeRequest() {
        ActivityCompat.requestPermissions(this,
                arrayOf(Manifest.permission.CALL_PHONE),
                CALL_REQUEST_CODE)
    }

}

----manfiest addition---
      <uses-permission android:name="android.permission.CALL_PHONE" />
        
        ----
      <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="in.eyehunt.implicitintentexample">

    <uses-permission android:name="android.permission.CALL_PHONE" />
    <application <=Example

-------
      val emailIntent = Intent(Intent.ACTION_SENDTO).apply { 
    data = Uri.parse("mailto:abc@xyz.com")
}
startActivity(Intent.createChooser(emailIntent, "Send feedback"))

Email Intent

//dependencies
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    ... ... ...
    
    // Add for using latest experimental build of Android Extensions
    androidExtensions {
        experimental = true
    }
}
//parceable class
@Parcelize
data class Category(
    var categoryId: Int,
    var categoryName: String
) : Parcelable
--next class--
@Parcelize
data class Item(
    var imageId: Int,
    var title: String,
    var price: Double,
    var category: Category
) : Parcelable
--passing--
val intent = Intent(this, AnotherActivity::class.java)
item.title = "Anas Rathore"
item.price = 50303
intent.putExtra("extra_item", item.title)
intent.putExtra("item_price", item.price)<- key and object
--retreving--
val item = intent.getParcelableExtra("extra_item")
val item = intent.getParceableExtra("item_price")
// Do something with the item (example: set Item title and price)

--if object is pre-defined, data is pre-defined or hard coded--
val student <- object = Student() <- class