Why ProgressBar is not Visible programmatically?

Question

I have a problem with ProgressBar Widget.

This is the ProgressBar in the layout

...
<RelativeLayout 
    android:layout_height="match_parent"
    android:layout_width="match_parent">
<ProgressBar
    android:id="@+id/progressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:indeterminate="true"
    android:layout_centerInParent="true"
    android:visibility="gone"
     />
</RelativeLayout>
....

This is the activity, where I have 2 methods.

....
private ProgressBar mProgressBar;
private Handler handler = new Handler();
private int i = 0;
...
protected void onCreate(Bundle savedInstanceState) {
...
    mProgressBar = findViewById(R.id.progressBar);
... 
}

private void showProgressBar() {
    mProgressBar.setVisibility(View.VISIBLE);
}

private void hideProgressBar() {
    mProgressBar.setVisibility(View.GONE);
}

The main activity have a Menu, on menu click I want to run a long task, so I want to show a progressBar

public boolean onOptionsItemSelected(MenuItem item) {
    showProgressBar();

    // This lines try to emulate a long task
    i = mProgressBar.getProgress();
    new Thread(new Runnable() {
        public void run() {
            while (i < 100) {
                i += 1;
                // Update the progress bar and display the current value in text view
                handler.post(new Runnable() {
                    public void run() {
                        mProgressBar.setProgress(i);
                        //txtView.setText(i+"/"+pgsBar.getMax());
                    }
                });
                try {
                    // Sleep for 100 milliseconds to show the progress slowly.
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }).start();

The lines below the call to the function is a test, I'm trying to delay the show and let me see the progress, but nothing is shown.

If I change the layout and change: android:visibility="visible" or remove the line

when the activity start I can see the progress, and when a line with hideProgressBar() function, in the end of onOptionsItemSelected(), is reached, the widget is hide or gone.

Where is the problem ? Is about Threads ?

I'm running this app in a Virtual Device. I could't find some settings about showing animations, but because I can see the progress if the visibility is set to VISIBLE.. I suppose that is not the problem.

Best regards

Compile SDK: 28 Android Studio: 3.6.3

UPDATE: Full Layout Source

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relativeLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/filial_appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/lista_filial_toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimary"
            android:elevation="4dp"
            app:layout_scrollFlags="scroll|enterAlways"
            android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </com.google.android.material.appbar.AppBarLayout>

    <RelativeLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent">
    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:indeterminate="true"
        android:layout_centerInParent="true"
        android:visibility="gone"
         />
    </RelativeLayout>

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"

        android:layout_below="@+id/filial_appbar"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        tools:context=".segregantes.ui.listafilial.ListaFilialActivity" />


</RelativeLayout>

UPDATE 2: New Code.

i = mProgressBar.getProgress();
runOnUiThread(new Runnable() {
    @Override
    public void run() {
        while (i < 100) {
            i += 1;
            mProgressBar.setProgress(i);
            try {
                // Sleep for 100 milliseconds to show the progress slowly.
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }
});

Answer 1

Please see the following code it shows horizontal bar:

<ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:indeterminate="true"
        android:max="100"
        android:progress="1"
        android:visibility="visible" />

Java code for showing progress bar

private int progressStatus = 0;

// Start long running operation in a background thread
    new Thread(new Runnable() {
        public void run() {
            while (progressStatus < 100) {
                progressStatus += 1;
                // Update the progress bar and display the
                //current value in the text view
                handler.post(new Runnable() {
                    public void run() {
                        progressBar.setProgress(progressStatus);
                        textView.setText(progressStatus+"/"+progressBar.getMax());
                    }
                });
                try {
                    // Sleep for 200 milliseconds.
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }).start();

Reference link: https://www.journaldev.com/9629/android-progressbar-example

Answer 2

You need to do UI operations on main thread so try doing this while setting progress

runOnUiThread(new Runnable() {
        public void run() {
             mProgressBar.setProgress(i);
        }
    });