Null image on firebase storage. How to save it original?

I have tried to solve an issue on my app but I couldn’t find a solution. I want the app to upload the images on Firebase Storage after the post is clicked. The problem is that when I click post the images are uploaded as .null and I can’t add them as posts on my app here is a photo of Firebase Storage:

Here is the code of PostsActivity:

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;
import android.content.ContentResolver;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.webkit.MimeTypeMap;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.example.selfcial.R;
import com.google.android.gms.tasks.Continuation;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.StorageTask;
import com.theartofdev.edmodo.cropper.CropImage;

import java.util.HashMap;

public class PostActivity extends AppCompatActivity {

    
    Uri imageUri;
    String myUrl;
    StorageTask uploadTask;
    StorageReference storageReference;

    ImageView close, image_added;
    TextView post;
    EditText description;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_post);

        close = findViewById(R.id.close);
        image_added = findViewById(R.id.image_added);
        post = findViewById(R.id.postPhoto);
        description = findViewById(R.id.description);


        storageReference = FirebaseStorage.getInstance().getReference("posts");

        close.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(PostActivity.this, MainActivity.class);
                startActivity(intent);
                finish();
            }
        });


        post.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                uploadImage();
            }
        });


        CropImage.activity()
                .setAspectRatio(1, 1)
                .start(PostActivity.this);

    }


    private String getFileExtension(Uri uri) {
        ContentResolver contentResolver = this.getContentResolver();
        MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();

        return mimeTypeMap.getExtensionFromMimeType(contentResolver.getType(uri));
    }


    private void uploadImage() {
        ProgressDialog progressDialog = new ProgressDialog(this);
        progressDialog.setMessage("Posting please wait..");
        progressDialog.show();


        if (imageUri != null) {
            StorageReference fileReference = storageReference.child(System.currentTimeMillis()
            + "." + getFileExtension(imageUri));

            uploadTask = fileReference.putFile(imageUri);
            uploadTask.continueWithTask(new Continuation() {
                @Override
                public Object then(@NonNull Task task) throws Exception {
                    if (task.isSuccessful()) {
                        throw task.getException();
                    }

                    return fileReference.getDownloadUrl();
                }
            }).addOnCompleteListener(new OnCompleteListener<Uri>() {
                @Override
                public void onComplete(@NonNull Task<Uri> task) {
                    if (task.isSuccessful()) {
                        Uri downloadUri = task.getResult();
                        myUrl = downloadUri.toString();

                        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("posts");

                        String postId = reference.push().getKey();

                        HashMap<String, Object> hashMap = new HashMap<>();
                        hashMap.put("postId", postId);
                        hashMap.put("postImage", myUrl);
                        hashMap.put("description", description.getText().toString());
                        hashMap.put("publisher", FirebaseAuth.getInstance().getCurrentUser().getUid());

                        reference.child(postId).setValue(hashMap);

                        progressDialog.dismiss();

                        startActivity(new Intent(PostActivity.this, MainActivity.class));
                        finish();
                    }else {
                        Toast.makeText(PostActivity.this, "Failed.", Toast.LENGTH_SHORT).show();
                    }
                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(PostActivity.this, ""+e.getMessage(), Toast.LENGTH_SHORT).show();
                }
            });
        }else {
            Toast.makeText(this, "No image selected.", Toast.LENGTH_SHORT).show();
        }
    }



    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == CropImage.CROP_IMAGE_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK) {
            CropImage.ActivityResult result = CropImage.getActivityResult(data);
            imageUri = result.getUri();

            image_added.setImageURI(imageUri);
        }else {
            Toast.makeText(this, "Something gone wrong", Toast.LENGTH_SHORT).show();
            startActivity(new Intent(PostActivity.this, MainActivity.class));
        }
    }
}

I thought that I have to initialize Uri inside onCreate method but nothing changed. What should it be?

Answer

It has been noticed that the method you are using to retrieve the file mime type doesn’t work on some devices. You could try some other alternatives like using apache commonsIO lib or alternatively try this code :

public String getMimeType(Uri uri) {           
String mimeType = null;
if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme())) {
    ContentResolver cr = getAppContext().getContentResolver();
    mimeType = cr.getType(uri);
} else {
    String fileExtension = MimeTypeMap.getFileExtensionFromUrl(uri
            .toString());
    mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(
            fileExtension.toLowerCase());
}
return mimeType;
}