Status bar re-appearance upon minimisation of fullscreen Android app

Question

I am developing a very simple fullscreen Android app: when started It will present a picture; no buttons, no actions. I have a problem with the top status bar as shown in the images of emulator below:
1) When I start the app everything is fine and I would like it to stay that way.
2) Once I click the square button to minimise the app I have a view over all opened programs, this is fine too.
3) Once I click on my app again it is maximised but the green top bar is now visible on top. I wish it looked like in (1)...

Below I paste my FullscreenActivity.java:

package com.example.myapp;

import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.view.MotionEvent;
import android.view.View;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * An example full-screen activity that shows and hides the system UI (i.e.
 * status bar and navigation/system bar) with user interaction.
 */
public class FullscreenActivity extends AppCompatActivity {

    /**
     * Some older devices needs a small delay between UI widget updates
     * and a change of the status and navigation bar.
     */
    private static final int UI_ANIMATION_DELAY = 0; //300;
    private final Handler mHideHandler = new Handler();
    private View mContentView;
    private final Runnable mHidePart2Runnable = new Runnable() {
        @SuppressLint("InlinedApi")
        @Override
        public void run() {
            // Delayed removal of status and navigation bar

            // Note that some of these constants are new as of API 16 (Jelly Bean)
            // and API 19 (KitKat). It is safe to use them, as they are inlined
            // at compile-time and do nothing on earlier devices.
            mContentView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE
                    | View.SYSTEM_UI_FLAG_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
        }
    };
    private View mControlsView;
    private final Runnable mShowPart2Runnable = new Runnable() {
        @Override
        public void run() {
            // Delayed display of UI elements
            ActionBar actionBar = getSupportActionBar();
            if (actionBar != null) {
                actionBar.show();
            }
            mControlsView.setVisibility(View.VISIBLE);
        }
    };
    private final Runnable mHideRunnable = new Runnable() {
        @Override
        public void run() {
            hide();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bluescreen);
        mControlsView = findViewById(R.id.fullscreen_content_controls);
        mContentView = findViewById(R.id.fullscreen_content);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        hide();
    }

    private void hide() {
        // Hide UI first
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.hide();
        }
        mControlsView.setVisibility(View.GONE);

        // Schedule a runnable to remove the status and navigation bar after a delay
        mHideHandler.removeCallbacks(mShowPart2Runnable);
        mHideHandler.postDelayed(mHidePart2Runnable, UI_ANIMATION_DELAY);
    }
}

score 1 · Accepted Answer · answered Jun 24 '19 at 20:45

1

When your activity goes to the background and then you bring it to front, the flags that you set are reseted. You call hide() from onPostCreate() which is called only when the activity is created or the screen is rotated.

If you want the hide() method to be called also when your app gets back from the background call it from onStart() or onWindowFocusChanged() when focus is true.

answered Jun 24 '19 at 20:45

Mohru

725
1
7
17

Thanks! I called the hide() from onStart() and it works. In case someone will face a similar problem, here is a nice flowchart of actions https://stackoverflow.com/questions/6812003/difference-between-oncreate-and-onstart – maciek Jun 24 '19 at 22:35

Status bar re-appearance upon minimisation of fullscreen Android app

1 Answers1