From https://codestringz.com/share-intent-for-a-bitmap-without-saving-a-file/

AndroidShareBitmap-Manifest.xml

/**
  * The code below is from https://codestringz.com/share-intent-for-a-bitmap-without-saving-a-file/
*/

<!-- 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"
    package="com.codestringz.mytestapp">
 
    <application
        ...
        ...>
        <activity
            ...
            .../>
        <activity
            ...
            .../>
             
        <!--File Provider-->
        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="${applicationId}.provider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_paths" />
        </provider>
         
    </application>
 
</manifest>

AndroidShareBitmap.java

/**
  * The code below is from https://codestringz.com/share-intent-for-a-bitmap-without-saving-a-file/
*/

// MainActivity.java
 @SuppressWarnings("ResultOfMethodCallIgnored")
    private void shareBitmap(@NonNull Bitmap bitmap)
    {
        //---Save bitmap to external cache directory---//
        //get cache directory
        File cachePath = new File(getExternalCacheDir(), "my_images/");
        cachePath.mkdirs();
 
        //create png file
        File file = new File(cachePath, "Image_123.png");
        FileOutputStream fileOutputStream;
        try
        {
            fileOutputStream = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
            fileOutputStream.flush();
            fileOutputStream.close();
 
        } catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } catch (IOException e)
        {
            e.printStackTrace();
        }
 
        //---Share File---//
        //get file uri
        Uri myImageFileUri = FileProvider.getUriForFile(this, getApplicationContext().getPackageName() + ".provider", file);
 
        //create a intent
        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        intent.putExtra(Intent.EXTRA_STREAM, myImageFileUri);
        intent.setType("image/png");
        startActivity(Intent.createChooser(intent, "Share with"));
    }
}

AndroidShareBitmap.xml

/**
  * The code below is from https://codestringz.com/share-intent-for-a-bitmap-without-saving-a-file/
*/

<!-- provider_paths.xml -->
<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-cache-path name="external_files" path="my_images/"/>
</paths>