MainActivity.kt
package com.cfsuman.jetpack
import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import kotlinx.android.synthetic.main.activity_main.*
import android.graphics.BitmapFactory
import java.io.BufferedInputStream
import java.io.IOException
import java.net.HttpURLConnection
import android.graphics.Bitmap
import androidx.work.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Download image
btnDownload.setOnClickListener{
// Create an one time work request
val downloadImageWork = OneTimeWorkRequest.Builder(DownloadImageWorker::class.java).build()
// Enqueue the work
WorkManager.getInstance().enqueue((downloadImageWork))
}
// Display the downloaded image
btnShow.setOnClickListener{
if (countSavedBitmap>0){
imageView.setImageURI(nameToUri(savedBitmapList[countSavedBitmap-1]))
textView.text = savedBitmapList[savedBitmapList.count()-1]
}else
{
toast("No downloaded image found")
}
}
}
}
// Worker class to download image
class DownloadImageWorker(context:Context, params: WorkerParameters): Worker(context,params){
override fun doWork(): Result {
// Do the work here
val url = stringToURL("https://www.freeimageslive.com/galleries/buildings/china/pics/nature_water3978.jpg")
// IMPORTANT - Put internet permission on manifest file
var connection: HttpURLConnection? = null
try {
// Initialize a new http url connection
connection = url?.openConnection() as HttpURLConnection
// Connect the http url connection
connection.connect()
// Get the input stream from http url connection
val inputStream = connection.getInputStream()
// Initialize a new BufferedInputStream from InputStream
val bufferedInputStream = BufferedInputStream(inputStream)
// Convert BufferedInputStream to Bitmap object
// Return the downloaded bitmap
val bmp:Bitmap? = BitmapFactory.decodeStream(bufferedInputStream)
bmp?.saveToInternalStorage(applicationContext)
Log.d("download","success")
return Result.success()
} catch (e: IOException) {
e.printStackTrace()
Log.d("download",e.toString())
} finally {
// Disconnect the http url connection
connection?.disconnect()
}
Log.d("download","failed")
return Result.failure()
}
}
xBitmap.kt
package com.cfsuman.jetpack
import android.content.Context
import android.content.ContextWrapper
import android.graphics.Bitmap
import android.net.Uri
import android.widget.Toast
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.io.OutputStream
import java.net.MalformedURLException
import java.net.URL
import java.util.*
// Extension function to save bitmap in internal storage
fun Bitmap.saveToInternalStorage(context: Context): Uri {
// Get the context wrapper instance
val wrapper = ContextWrapper(context)
// Initializing a new file
// The bellow line return a directory in internal storage
var file = wrapper.getDir("images", Context.MODE_PRIVATE)
// Create a file to save the image
file = File(file, "${UUID.randomUUID()}.png")
try {
// Get the file output stream
val stream: OutputStream = FileOutputStream(file)
// Compress bitmap
this.compress(Bitmap.CompressFormat.PNG, 100, stream)
// Flush the stream
stream.flush()
// Close stream
stream.close()
} catch (e: IOException){ // Catch the exception
e.printStackTrace()
}
// Return the saved image uri
return Uri.parse(file.absolutePath)
}
// Extension function to count internal storage images
val Context.countSavedBitmap:Int
get(){
val wrapper = ContextWrapper(this)
val file = wrapper.getDir("images", Context.MODE_PRIVATE)
val length = file.list().size
return length
}
// Extension function to get internal storage images list
val Context.savedBitmapList:MutableList<String>
get(){
val wrapper = ContextWrapper(this)
val file = wrapper.getDir("images", Context.MODE_PRIVATE)
val list = file.list().asList().toMutableList()
return list
}
fun Context.nameToUri(name:String):Uri{
val wrapper = ContextWrapper(this)
// Initializing a new file
// The bellow line return a directory in internal storage
var file = wrapper.getDir("images", Context.MODE_PRIVATE)
// Create a file to save the image
file = File(file, name)
val uri = Uri.fromFile(file)
return uri
}
// Custom method to convert string to url
fun stringToURL(urlString: String): URL? {
try {
return URL(urlString)
} catch (e: MalformedURLException) {
e.printStackTrace()
}
return null
}
fun Context.toast(message:String)=
Toast.makeText(this,message, Toast.LENGTH_SHORT).show()
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/rootLayout"
tools:context=".MainActivity"
android:background="#fdfdfc">
<Button
android:text="Download Image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/btnDownload"
android:layout_marginTop="8dp"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginStart="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintHorizontal_bias="0.498"/>
<Button
android:text="Show Image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/btnShow"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="@+id/btnDownload"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="8dp"/>
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
tools:srcCompat="@tools:sample/avatars"
android:id="@+id/imageView"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="8dp"
app:layout_constraintHorizontal_bias="0.0"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="@+id/textView"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:text="Image URI"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textView"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="@+id/btnShow"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="8dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>
gradle dependencies
// WorkManager
def work_version = "1.0.0-beta02"
implementation "android.arch.work:work-runtime:$work_version"
- kotlin - ChipGroup multi selection
- MaterialCardView example
- kotlin - WorkManager parameters
- kotlin - ViewModel LiveData
- kotlin syntax - List sortBy and sortByDescending
- kotlin syntax - List sort and sortDescending
- kotlin syntax - List sorted and sortedDescending
- kotlin syntax - List sort by multiple fields
- kotlin syntax - Sort list using comparator
- kotlin syntax - List sort descending using multiple fields