android kotlin - Save image to external storage example

MainActivity.kt

package com.cfsuman.kotlinexamples

import android.content.Context
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
import android.graphics.Bitmap
import android.graphics.drawable.BitmapDrawable
import android.net.Uri
import android.os.Build
import android.support.v4.content.ContextCompat
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.io.OutputStream
import java.util.*
import android.os.Environment
import android.widget.Toast


class MainActivity : AppCompatActivity() {

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

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
            // Check run time permission for write external storage
            // android.permission.WRITE_EXTERNAL_STORAGE
        }

        // Get the bitmap from given drawable object
        val drawable = ContextCompat.getDrawable(applicationContext,R.drawable.flower16)
        val bitmap = (drawable as BitmapDrawable).bitmap

        // Click listener for button widget
        button.setOnClickListener{
            // Save the image in external storage and get the uri
            val uri:Uri = saveImageToExternalStorage(bitmap)

            // Display the external storage saved image in image view
            image_view_saved.setImageURI(uri)

            // Show the saved image uri
            text_view.text = "Saved: $uri"
        }
    }


    // Method to save an image to external storage
    private fun saveImageToExternalStorage(bitmap:Bitmap):Uri{
        // Get the external storage directory path
        val path = Environment.getExternalStorageDirectory().toString()

        // Create a file to save the image
        val file = File(path, "${UUID.randomUUID()}.jpg")

        try {
            // Get the file output stream
            val stream: OutputStream = FileOutputStream(file)

            // Compress the bitmap
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream)

            // Flush the output stream
            stream.flush()

            // Close the output stream
            stream.close()
            toast("Image saved successful.")
        } catch (e: IOException){ // Catch the exception
            e.printStackTrace()
            toast("Error to save image.")
        }

        // Return the saved image path to uri
        return Uri.parse(file.absolutePath)
    }
}


// Extension function to show toast message
fun Context.toast(message: String) {
    Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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/root_layout"
    android:background="#ded5d2"
    android:padding="16dp"
    android:orientation="vertical"
    >
    <ImageView
        android:id="@+id/image_view_source"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:src="@drawable/flower16"
        />
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save Image To External Storage"
        android:layout_gravity="center_horizontal"
        android:layout_margin="10dp"
        />
    <TextView
        android:id="@+id/text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#ff2079"
        android:layout_margin="10dp"
        style="@style/Base.TextAppearance.AppCompat.Medium"
        />
    <ImageView
        android:id="@+id/image_view_saved"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        />
</LinearLayout>

AndroidManiest.xml [Permission]

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>