MainActivity.kt
package com.example.jetpack
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.coroutines.*
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.flowOn
class MainActivity : AppCompatActivity() {
lateinit var flow:Flow<String>
lateinit var colors:List<String>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setupFlow()
setupClicks()
colors = listOf(
"African violet",
"Air superiority blue",
"Alloy orange",
"Antique bronze",
"Arylide yellow",
"Atomic tangerine",
"Bittersweet shimmer"
)
}
@ExperimentalCoroutinesApi
private fun setupFlow(){
flow = flow{
colors.forEach {
delay(1000)
emit(it)
}
}.flowOn(Dispatchers.Default)
}
private fun setupClicks(){
button.setOnClickListener {
textView.text = ""
CoroutineScope(Dispatchers.Main).launch {
flow.collect{
textView.append("\n"+it)
}
}
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Show Color List"
android:backgroundTint="#E30022"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text=""
android:textAppearance="@style/TextAppearance.AppCompat.Large"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/button" />
</androidx.constraintlayout.widget.ConstraintLayout>
build.gradle dependencies [add]
// Kotlin coroutines
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.3"
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.3"


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