Progress Bar is not showing up when visibility is changed to visible in java code

Question

I'm making progress bar visible and invisible in async task. I'm doing some db operations in async task while doing operations I want to show progressdialog. as soon as it finishes its operation. I want to make it invisible. My code is below. Problem is progresssbar does not show up.

activity_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:id="@+id/activity_course_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="info.lms.CourseList">

<!-- The ActionBar displayed at the top -->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
<include
    layout="@layout/tool_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

<ListView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/course_list"></ListView>

</LinearLayout>

<ProgressBar
    android:id="@+id/progressBar"
    style="?android:attr/progressBarStyle"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:visibility="invisible"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true" />
</RelativeLayout>

I'm using an async task where I want to make progress bar visible and invisible

    private class tmpCourseOfferingTask extends AsyncTask<String,Void,JSONObject> {

    public tmpCourseOfferingTask(){
        super();
    }
    @Override
    protected void onPreExecute(){

    super.onPreExecute();

    progressBar.setVisibility(View.VISIBLE);

    }
    @Override
    protected JSONObject doInBackground(String...params){

        return null;
    }

    @Override
    protected void onPostExecute(JSONObject json) {


    Thread.sleep(5000);



   } catch (JSONException e) {
            e.printStackTrace();
   } catch (InterruptedException e) {
            e.printStackTrace();
   }

   progressBar.setVisibility(View.GONE);

}

Answer 1

First, remove the Thread.Sleep(millis) from onPostExecute and put it in the doInBackground. onPostExecute, as onPreExecute, runs on the main thread so the sleep should be put in the background process.

your flow (at the moment) is this:

• asynctask created
• pre-execute = progressbar visible
• onbackground = nothing
• post-execute = thread sleep . --> this is stopping the UI thread and the view has no time to update the visibility because it's stopped
• progressbar = View.GONE .

This is not showing the progress because the thread is being stopped immediatly and the View changes are applied once after a return. I use the code as below and it works for me.

Another thing is that your catch is without a try (?) so this code is missing something or is not working. With those two fixes it will work. do something like:

 private class tmpCourseOfferingTask extends AsyncTask<String,Void,JSONObject> {

    public tmpCourseOfferingTask(){
        super();
    }
    @Override
    protected void onPreExecute(){

    super.onPreExecute();

    progressBar.setVisibility(View.VISIBLE);

    }
    @Override
    protected JSONObject doInBackground(String...params){

      try{
      SystemClock.sleep(timeInMills);
      }catch(Exception ignored){
      }finally{
        return null;
      }
   }

    @Override
    protected void onPostExecute(JSONObject json) {
       progressBar.setVisibility(View.GONE);
    }
 }

Another fix:

You have a RelativeLayout with a LinearLayout and a progressbar.. also the progressbar should be with visibility "GONE" so that the view space is not kept used. You can remove the useless LinearLayout and do something like this:

<?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:id="@+id/activity_course_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="info.lms.CourseList">

<include
    amdrpod:id="@+id/includeId"
    layout="@layout/tool_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

<ListView
    android:layout_below="@+id/includeId"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/course_list"/>

<ProgressBar
    android:id="@+id/progressBar"
    style="?android:attr/progressBarStyle"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:visibility="gone"
    android:layout_centerInParent="true" />
</RelativeLayout>

(wrote by hand, might be not perfect)

Answer 2

To make sure to see the ProgressBar use bringToFront() at PreExecute() like this:

progressBar.bringToFront();

btw I think Pier's answer should do the trick.

Answer 3

Try to wrap your Progressbar inside linerlayout like below and then check show and hide functionality and use the liner layout ID to show and hide.

 <LinearLayout
    android:id="@+id/Progress"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center"
    android:orientation="vertical"
    android:visibility="gone" >

   <ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="invisible"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true" />
</LinearLayout>