my android app not uploading photo directly to Dropbox app folder using API

i have made some changes to my code to show only confirmation in uploading success or not and when i use the app and capture image message pop up und tell me error uploading to dropbox:null this is my new code so the upload process dosn´t success 

package com.example.decamera;

import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;
import android.net.Uri;
import android.util.Log;



import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.camera.core.Camera;
import androidx.camera.core.CameraSelector;
import androidx.camera.core.ImageCapture;
import androidx.camera.core.ImageCaptureException;
import androidx.camera.core.Preview;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.camera.view.PreviewView;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.lifecycle.LifecycleOwner;

import com.dropbox.core.DbxRequestConfig;
import com.dropbox.core.v2.files.FileMetadata;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.common.util.concurrent.ListenableFuture;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private static final int CAMERA_PERMISSION_REQUEST = 100;
    private static final int LOCATION_PERMISSION_REQUEST = 101;
    private static final String[] REQUIRED_CAMERA_PERMISSIONS = new String[]{Manifest.permission.CAMERA};
    private static final String[] REQUIRED_LOCATION_PERMISSIONS = new String[]{Manifest.permission.ACCESS_FINE_LOCATION};

    private PreviewView previewView;
    private ImageCapture imageCapture;
    private TextView addressTextView;

    private ExecutorService cameraExecutor = Executors.newSingleThreadExecutor();
    private FusedLocationProviderClient fusedLocationProviderClient;
    private Geocoder geocoder;

    // Dropbox variables
    private static final String ACCESS_TOKEN = "sl.BqXWiazZAvf1uR-ONm9kH7XTjxew29xKWUh46mSxUg5CcRKKImYicad6kMsgMCLDHHNeP2mcyww-XWHNX2jP2CQPIFnHOfTu--sTcmTl5DgrgdH_Cb1UiR8V5tl3-q4L9MgywIHeaIFOEWfRIOlylMs";

    private DbxRequestConfig config;
    private com.dropbox.core.v2.DbxClientV2 dropboxClient;

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

        previewView = findViewById(R.id.previewView);
        ImageButton captureButton = findViewById(R.id.captureButton);
        addressTextView = findViewById(R.id.addressTextView);

        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
        geocoder = new Geocoder(this, Locale.getDefault());

        // Initialize Dropbox variables
        config = DbxRequestConfig.newBuilder("de_camera_app").build();
        dropboxClient = new com.dropbox.core.v2.DbxClientV2(config, ACCESS_TOKEN);

        captureButton.setOnClickListener(this);

        if (allPermissionsGranted()) {
            startCamera();
            getLastLocation();
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_CAMERA_PERMISSIONS, CAMERA_PERMISSION_REQUEST);
        }
    }

    private void startCamera() {
        ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(this);

        cameraProviderFuture.addListener(() -> {
            try {
                ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
                bindPreview(cameraProvider);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }, ContextCompat.getMainExecutor(this));
    }

    private void bindPreview(ProcessCameraProvider cameraProvider) {
        Preview preview = new Preview.Builder().build();

        CameraSelector cameraSelector = new CameraSelector.Builder()
                .requireLensFacing(CameraSelector.LENS_FACING_BACK)
                .build();

        Camera camera = cameraProvider.bindToLifecycle((LifecycleOwner) this, cameraSelector, preview);

        preview.setSurfaceProvider(previewView.getSurfaceProvider());

        imageCapture = new ImageCapture.Builder()
                .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
                .setTargetRotation(previewView.getDisplay().getRotation()) // Add this line
                .build();

        // Re-bind use cases to the camera
        cameraProvider.unbindAll();
        cameraProvider.bindToLifecycle((LifecycleOwner) this, cameraSelector, preview, imageCapture);
    }

    private void getLastLocation() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
            fusedLocationProviderClient.getLastLocation()
                    .addOnSuccessListener(this, new OnSuccessListener<Location>() {
                        @Override
                        public void onSuccess(Location location) {
                            if (location != null) {
                                updateAddress(location);
                            }
                        }
                    });
        } else {
            // Request location permission
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, LOCATION_PERMISSION_REQUEST);
        }
    }

    private void updateAddress(Location location) {
        try {
            List<Address> addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
            if (addresses != null && addresses.size() > 0) {
                Address address = addresses.get(0);
                String fullAddress = address.getAddressLine(0);
                addressTextView.setText(fullAddress);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.captureButton) {
            captureAndUploadToDropbox(); // Call the new method
        }
    }

    private void captureAndUploadToDropbox() {
        // Capture the image and directly upload it to Dropbox
        ImageCapture.OutputFileOptions outputFileOptions =
                new ImageCapture.OutputFileOptions.Builder(createImageFile()).build();

        imageCapture.takePicture(outputFileOptions, ContextCompat.getMainExecutor(this), new ImageCapture.OnImageSavedCallback() {
            @Override
            public void onImageSaved(@Nullable ImageCapture.OutputFileResults outputFileResults) {
                Uri savedUri = outputFileResults.getSavedUri();

                if (savedUri != null) {
                    File savedPhoto = new File(savedUri.getPath());

                    // Upload the photo to Dropbox
                    uploadToDropbox(savedPhoto);
                } else {
                    runOnUiThread(() -> Toast.makeText(MainActivity.this, "Error getting saved file URI", Toast.LENGTH_SHORT).show());
                }
            }

            @Override
            public void onError(@NonNull ImageCaptureException exception) {
                runOnUiThread(() -> Toast.makeText(MainActivity.this, "Error capturing image: " + exception.getMessage(), Toast.LENGTH_SHORT).show());
            }
        });
    }



    private void uploadToDropbox(File photoFile) {
        try {
            // Get the file name
            String fileName = photoFile.getName();

            // Log the file path before upload
            Log.d("DropboxUpload", "Uploading file: " + photoFile.getAbsolutePath());

            // Open the photo file
            FileInputStream fis = new FileInputStream(photoFile);

            // Specify the remote path on Dropbox where you want to upload the file
            String remotePath = "/Apps/Bau" + fileName; // Replace "Bau" with your desired folder name

            // Upload the photo file
            FileMetadata metadata = dropboxClient.files().uploadBuilder(remotePath)
                    .uploadAndFinish(fis);

            // You can handle the metadata response if needed
            // metadata.getName(), metadata.getSize(), etc.

            runOnUiThread(() -> Toast.makeText(MainActivity.this, "Photo uploaded to Dropbox successfully", Toast.LENGTH_SHORT).show());
        } catch (Exception e) {
            e.printStackTrace();
            runOnUiThread(() -> Toast.makeText(MainActivity.this, "Error uploading to Dropbox: " + e.getMessage(), Toast.LENGTH_SHORT).show());
        }
    }


    private File createImageFile() {
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);

        try {
            if (storageDir != null) {
                return File.createTempFile(imageFileName, ".jpg", storageDir);
            } else {
                runOnUiThread(() -> Toast.makeText(MainActivity.this, "Error creating storage directory", Toast.LENGTH_SHORT).show());
            }
        } catch (IOException e) {
            e.printStackTrace();
            runOnUiThread(() -> Toast.makeText(MainActivity.this, "Error creating photo file", Toast.LENGTH_SHORT).show());
        }

        return null;
    }

    private boolean allPermissionsGranted() {
        for (String permission : REQUIRED_CAMERA_PERMISSIONS) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
        return true;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        if (requestCode == CAMERA_PERMISSION_REQUEST) {
            if (allPermissionsGranted()) {
                startCamera();
                getLastLocation();
            } else {
                runOnUiThread(() -> Toast.makeText(this, "Camera permissions not granted.", Toast.LENGTH_SHORT).show());
                finish();
            }
        } else if (requestCode == LOCATION_PERMISSION_REQUEST) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                getLastLocation();
            } else {
                runOnUiThread(() -> Toast.makeText(this, "Location permissions not granted.", Toast.LENGTH_SHORT).show());
            }
        }
    }
}