Why screenshot is not made after click on floating widget button which is connected with screenshot function?

Question

I'm writing a program which will make screenshot after click on floating widget. I fixed all errors, floating widget is loaded after permission granted. In a separate screenshot app everything is OK too.

I tried to connect it and build screenshot to floating code and this program has no errors, but screenshot is not made after click on floating widget button. This is part of connection in Myscreenshot.java:

setContentView(R.layout.floating_widget_layout);
Button screenshotButton = findViewById(R.id.floating_button);

Could you check my code if you would see any possible mistake?

MainActivity.java

package com.example.project4;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        startFloatingWidgetService();
    }

    private void startFloatingWidgetService() {
        Intent intent = new Intent(this, FloatingWidgetService.class);
        startService(intent);
    }
}

FloatingWidgetService.java

package com.example.project4;

import android.app.Service;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.net.Uri;
import android.os.Build;
import android.os.IBinder;
import android.provider.Settings;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;

public class FloatingWidgetService extends Service {

    private WindowManager mWindowManager;
    private View mFloatingWidgetView;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    // Method to request the SYSTEM_ALERT_WINDOW permission
    private void requestOverlayPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
            intent.setData(Uri.parse("package:" + getPackageName()));
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(intent);
        }
    }

    // Method to create the floating widget
    private void createFloatingWidget() {
        // Inflate the layout for the floating widget
        mFloatingWidgetView = LayoutInflater.from(this).inflate(R.layout.floating_widget_layout,
                null);

        // Initialize the button on the floating widget
        Button button = mFloatingWidgetView.findViewById(R.id.floating_button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Handle the button click event
                showTextDialog();
                // You can perform other actions here as needed
            }
        });

        // Initialize the WindowManager
        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);

        // Set up WindowManager.LayoutParams for the floating widget
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );

        // Set the gravity of the floating widget (position on the screen)
        params.gravity = Gravity.BOTTOM | Gravity.END;

        // Add the floating widget to the WindowManager
        mWindowManager.addView(mFloatingWidgetView, params);
    }

    @Override
    public void onCreate() {
        super.onCreate();

        // Check if the permission is granted (only for API level 23 and higher)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !Settings.canDrawOverlays(this)) {
            // You don't have permission to draw overlays, so request it
            requestOverlayPermission();
        } else {
            // Permission is granted, proceed with creating the floating widget
            createFloatingWidget();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mFloatingWidgetView != null && mWindowManager != null) {
            mWindowManager.removeView(mFloatingWidgetView);
        }
    }

    private void showTextDialog() {

    }
}

Myscreenshot.java

package com.example.project4;

import android.Manifest;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.File;
import java.io.FileOutputStream;
import java.util.Date;

public class Myscreenshot extends AppCompatActivity {

    private static final int REQUEST_CODE_PERMISSION = 101;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.floating_widget_layout);

        Button screenshotButton = findViewById(R.id.floating_button);
        screenshotButton.setOnClickListener(v -> {
            if (checkPermission()) {
                takeScreenshot();
            } else {
                requestPermission();
            }
        });
    }

    private boolean checkPermission() {
        int permission = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        return permission == PackageManager.PERMISSION_GRANTED;
    }

    private void requestPermission() {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_PERMISSION);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_CODE_PERMISSION) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                takeScreenshot();
            } else {
                Toast.makeText(this, "Permission denied. Unable to take screenshot.", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void takeScreenshot() {
        try {
            View rootView = getWindow().getDecorView().getRootView();
            rootView.setDrawingCacheEnabled(true);
            Bitmap bitmap = Bitmap.createBitmap(rootView.getDrawingCache());
            rootView.setDrawingCacheEnabled(false);

            String fileName = "screenshot_" + new Date().getTime() + ".png";
            File screenshotFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), fileName);

            FileOutputStream outputStream = new FileOutputStream(screenshotFile);
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
            outputStream.flush();
            outputStream.close();

            Toast.makeText(this, "Screenshot saved: " + screenshotFile.getAbsolutePath(), Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "Error taking screenshot.", Toast.LENGTH_SHORT).show();
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/start_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="ahoj"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

floating_widget_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <Button
        android:id="@+id/floating_button"
        android:layout_width="wrap_content"
        android:layout_height="33dp"
        android:layout_gravity="end"
        android:background="@android:color/holo_red_light"
        android:text="asdasda"
        android:textColor="#212121" />

</LinearLayout>

Androidmanifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Project4"
        tools:targetApi="31">

        <service
            android:name=".FloatingWidgetService"
            android:enabled="true"
            android:exported="true" />

        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>