Invisible Progress Bar not showing up through code

Issue

I'm making a project Android application that takes an image URL, downloads the image and displays the image. In case of an image of bigger size i want to show the user an indeterminate progress that the image is being downloading.

Java Code:

public class MainActivity extends AppCompatActivity {

    ImageView downloadedImg;
    ProgressBar progressBar;
    Handler handler;


    public void downloadImage(View view){

        progressBar.setVisibility(View.VISIBLE);

        ImageDownloader task = new ImageDownloader();
        Bitmap myimage;
        try {
            myimage = task.execute("http://wallpaperswide.com/download/high_tech_earth-wallpaper-2880x1800.jpg").get();
            downloadedImg.setImageBitmap(myimage);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        downloadedImg = (ImageView)findViewById(R.id.imageView);
        progressBar = (ProgressBar)findViewById(R.id.pbar);
        handler = new Handler();

    }

    public class ImageDownloader extends AsyncTask<String,Void,Bitmap>{

        protected void onPreExecute(){
            super.onPreExecute();
            //progressBar.setVisibility(View.VISIBLE);
        }

        @Override
        protected Bitmap doInBackground(String... urls) {
            try {
                URL url = new URL(urls[0]);
                HttpURLConnection connection = (HttpURLConnection)url.openConnection();
                connection.connect();
                InputStream inputStream = connection.getInputStream();
                Bitmap mybitmap = BitmapFactory.decodeStream(inputStream);
                return mybitmap;
            }
            catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            handler.post(new Runnable() {
                @Override
                public void run() {
                    progressBar.setVisibility(View.GONE);
                    downloadedImg.setVisibility(View.VISIBLE);
                }
            });
        }

    }

    public void reset(View view){
        downloadedImg.setVisibility(View.GONE);
        progressBar.setVisibility(View.INVISIBLE);
    }
}

XML code:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    tools:context="com.example.syeddanish.downloadingimages.MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:onClick="downloadImage"
        android:text="Download Image" />

    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button"
        android:onClick="reset"
        android:text="Reset" />

    <ProgressBar
        android:id="@+id/pbar"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:indeterminate="true"
        android:visibility="invisible" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:visibility="gone"
        android:layout_below="@+id/button1" />


</RelativeLayout>

The issue i'm facing is that i want the progress bar to become visible when the download starts(i.e when "Download Image button is pressed"). I'm trying to do this in two ways i.e

1. By using progressbar.setVisibility(View.VISIBLE); in the start of the onClick method of "Download Image" button. or
2. By using progressbar.setVisibility(View.VISIBLE); in theonPreExecute() method of the ASyncTask but the progress bardoes not shows up using any of the above mentioned ways.

Can anyone please point out what i am doing wrong?

Solution

try put downloadedImg.setImageBitmap(myimage); inside onPostExecute(Bitmap bitmap)handler and change:

myimage = task.execute("http://wallpaperswide.com/download/high_tech_earth-wallpaper-2880x1800.jpg").get();

to:

task.execute("http://wallpaperswide.com/download/high_tech_earth-wallpaper-2880x1800.jpg");

also put Bitmap myimage; as global variable on your Asynctask class and change:

Bitmap mybitmap = BitmapFactory.decodeStream(inputStream);
            return mybitmap;

to:

myimage= BitmapFactory.decodeStream(inputStream);

on doInBackground

Answered By - aru van housen