When our application does a task that takes a considerable amount of time, it is common sense to show the progress of the task to the user.
This is a good User Experience practice. In this tutorial i will be discussing the implementation of a process-progress dialog.
As an example, i am displaying a progress bar that runs while the app downloads an image from the web. And once the image is downloaded
completely i am showing the image in a image view. You could modify this example and try it with any file type you may wish. That could be fun!
package
com.example.androidhive;
import
java.io.BufferedInputStream;
import
java.io.FileOutputStream;
import
java.io.InputStream;
import
java.io.OutputStream;
import
java.net.URL;
import
java.net.URLConnection;
import
android.app.Activity;
import
android.app.Dialog;
import
android.app.ProgressDialog;
import
android.graphics.drawable.Drawable;
import
android.os.AsyncTask;
import
android.os.Bundle;
import
android.os.Environment;
import
android.util.Log;
import
android.view.View;
import
android.widget.Button;
import
android.widget.ImageView;
public
class
AndroidDownloadFileByProgressBarActivity
extends
Activity {
// button to show progress dialog
Button btnShowProgress;
// Progress Dialog
private
ProgressDialog pDialog;
ImageView my_image;
// Progress dialog type (0 - for Horizontal progress bar)
public
static
final
int
progress_bar_type =
0
;
// File url to download
@Override
public
void
onCreate(Bundle savedInstanceState) {
super
.onCreate(savedInstanceState);
setContentView(R.layout.main);
// show progress bar button
btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
// Image view to show image after downloading
my_image = (ImageView) findViewById(R.id.my_image);
/**
* Show Progress bar click event
* */
btnShowProgress.setOnClickListener(
new
View.OnClickListener() {
@Override
public
void
onClick(View v) {
// starting new Async Task
new
DownloadFileFromURL().execute(file_url);
}
});
}
/**
* Showing Dialog
* */
@Override
protected
Dialog onCreateDialog(
int
id) {
switch
(id) {
case
progress_bar_type:
// we set this to 0
pDialog =
new
ProgressDialog(
this
);
pDialog.setMessage(
"Downloading file. Please wait..."
);
pDialog.setIndeterminate(
false
);
pDialog.setMax(
100
);
pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pDialog.setCancelable(
true
);
pDialog.show();
return
pDialog;
default
:
return
null
;
}
}
/**
* Background Async Task to download file
* */
class
DownloadFileFromURL
extends
AsyncTask<String, String, String> {
/**
* Before starting background thread
* Show Progress Bar Dialog
* */
@Override
protected
void
onPreExecute() {
super
.onPreExecute();
showDialog(progress_bar_type);
}
/**
* Downloading file in background thread
* */
@Override
protected
String doInBackground(String... f_url) {
int
count;
try
{
URL url =
new
URL(f_url[
0
]);
URLConnection conection = url.openConnection();
conection.connect();
// this will be useful so that you can show a tipical 0-100% progress bar
int
lenghtOfFile = conection.getContentLength();
// download the file
InputStream input =
new
BufferedInputStream(url.openStream(),
8192
);
// Output stream
OutputStream output =
new
FileOutputStream(
"/sdcard/downloadedfile.jpg"
);
byte
data[] =
new
byte
[
1024
];
long
total =
0
;
while
((count = input.read(data)) != -
1
) {
total += count;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress(
""
+(
int
)((total*
100
)/lenghtOfFile));
// writing data to file
output.write(data,
0
, count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
}
catch
(Exception e) {
Log.e(
"Error: "
, e.getMessage());
}
return
null
;
}
/**
* Updating progress bar
* */
protected
void
onProgressUpdate(String... progress) {
// setting progress percentage
pDialog.setProgress(Integer.parseInt(progress[
0
]));
}
/**
* After completing background task
* Dismiss the progress dialog
* **/
@Override
protected
void
onPostExecute(String file_url) {
// dismiss the dialog after the file was downloaded
dismissDialog(progress_bar_type);
// Displaying downloaded image into image view
// Reading image path from sdcard
String imagePath = Environment.getExternalStorageDirectory().toString() +
"/downloadedfile.jpg"
;
// setting downloaded into image view
my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}
}
}
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