我已经创建了一个android工作室项目，其中包含一个直到圣诞节的倒计时。我使用两个图像来创建倒计时计时器的背景和轮廓。我已经使该应用程序看起来不错，我想知道是否有任何办法，以设置为我的手机的背景项目，如果它是可能的，如何做到这一点。下面的代码是我如何设置计时器并给出它的值。我有什么需要改变的吗？

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);
    }
}