How do I set my android studio project as my phones background?

Question

I have created an android studio project that contains a countdown until Christmas. I use two images to create the background and the outline for the countdown timer. I have made the application look nice and I was wondering if there is any way to set the project as my phone's background and if it is possible how to do it. The code below is how I set the timer and give it its value. Is there anything I need to change to make this possible?

package com.example.holidaycountdown;

import android.app.WallpaperManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private TextView txtTimerDay, txtTimerHour, txtTimerMinute, txtTimerSecond;
    private TextView tvEvent;
    private Handler handler;
    private Runnable runnable;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txtTimerDay = (TextView) findViewById(R.id.txtTimerDay);
        txtTimerHour = (TextView) findViewById(R.id.txtTimerHour);
        txtTimerMinute = (TextView) findViewById(R.id.txtTimerMinute);
        txtTimerSecond = (TextView) findViewById(R.id.txtTimerSecond);
        tvEvent = (TextView) findViewById(R.id.tvhappyevent);
        countDownStart();

        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                setWallpaper();
            }
        });
    }
    private void setWallpaper() {
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.wallpaper);
        WallpaperManager manager = WallpaperManager.getInstance(getApplicationContext());
        try{
            manager.setBitmap(bitmap);
            Toast.makeText(this, "Wallpaper set!", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            Toast.makeText(this, "Error!", Toast.LENGTH_SHORT).show();
        }
    }
    public void countDownStart() {
        handler = new Handler();
        runnable = new Runnable() {
            @Override
            public void run() {
                handler.postDelayed(this, 1000);
                try {
                    SimpleDateFormat dateFormat = new SimpleDateFormat(
                            "yyyy-MM-dd");
                    // Please here set your event date//YYYY-MM-DD
                    Date futureDate = dateFormat.parse("2020-12-25");
                    Date currentDate = new Date();
                    if (!currentDate.after(futureDate)) {
                        long diff = futureDate.getTime()
                                - currentDate.getTime();
                        long days = diff / (24 * 60 * 60 * 1000);
                        diff -= days * (24 * 60 * 60 * 1000);
                        long hours = diff / (60 * 60 * 1000);
                        diff -= hours * (60 * 60 * 1000);
                        long minutes = diff / (60 * 1000);
                        diff -= minutes * (60 * 1000);
                        long seconds = diff / 1000;
                        txtTimerDay.setText("" + String.format("%02d", days));
                        txtTimerHour.setText("" + String.format("%02d", hours));
                        txtTimerMinute.setText(""
                                + String.format("%02d", minutes));
                        txtTimerSecond.setText(""
                                + String.format("%02d", seconds));
                    } else {
                        tvEvent.setVisibility(View.VISIBLE);
                        tvEvent.setText("The event started!");
                        textViewGone();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };
        handler.postDelayed(runnable, 1 * 1000);
    }

    public void textViewGone() {
        findViewById(R.id.LinearLayout10).setVisibility(View.GONE);
        findViewById(R.id.LinearLayout11).setVisibility(View.GONE);
        findViewById(R.id.LinearLayout12).setVisibility(View.GONE);
        findViewById(R.id.LinearLayout13).setVisibility(View.GONE);
        findViewById(R.id.textView1).setVisibility(View.GONE);
        findViewById(R.id.textView2).setVisibility(View.GONE);
    }
}

Answer 1

Seems like you need to create an app widget for your application(App Widgets are miniature application views that can be embedded in other applications (such as the Home screen) and receive periodic updates).

Here is a useful tutorial

Google's tutorial