Upload photo to Firebase Storage

Question

I'm trying to build a MainActivity that comprises two Buttons, one for taking a picture with the camera and uploading it to Firebase Storage, and the other one to download the image from Firebase Storage and show it on an ImageView.

Right now, I'm stuck with the upload function. I can take the picture and save it into the app directory. I would like to upload the saved picture into Firebase Storage.

My MainActivity.java (based on the Firebase developers tutorial) is the following:

package com.example.mathi.image;

import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.UploadTask;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

static final int REQUEST_TAKE_PHOTO = 1;
String mCurrentPhotoPath;

private Button btn_upload;
private Button btn_download;

//Firebase
FirebaseStorage storage;
StorageReference storageReference;

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

    btn_upload = (Button)findViewById(R.id.btn_upload);
    btn_download = (Button)findViewById(R.id.btn_download);

    btn_upload.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dispatchTakePictureIntent();



        }
    });

    btn_download.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });


}

private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File

        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(this,
                    "com.example.mathi.image.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
            upload_photo();
        }
    }
}



private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = image.getAbsolutePath();
    return image;
}


private void upload_photo(){
    Uri file = Uri.fromFile(new File(mCurrentPhotoPath));
    UploadTask uploadTask = storageReference.putFile(file);

// Register observers to listen for when the download is done or if 
it fails
    uploadTask.addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception exception) {
            // Handle unsuccessful uploads
        }
    }).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            // taskSnapshot.getMetadata() contains file metadata such as size, content-type, etc.
            // ...
        }
    });
}

}

In the debugger I have the following error:

java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.storage.UploadTask com.google.firebase.storage.StorageReference.putFile(android.net.Uri)' on a null object reference at com.example.mathi.image.MainActivity.upload_photo(MainActivity.java:112)

Line 112 is the following line:

UploadTask uploadTask = storageReference.putFile(file);

The file is created on the local dir when I remove the upload() method. However, with the upload() method, the app crashes.

Does anyone knows what I am missing?

how can I make it work ? I shouldn't use mCurrentPhotoPath ? — Mathias, Nov 15 '18 at 09:54
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Grimthorr, Nov 15 '18 at 10:13

score 2 · Accepted Answer · answered Nov 15 '18 at 10:00

Try this code

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



private void CaptureImageFromCamera() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        startActivityForResult(takePictureIntent, 200);
    }
}

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

    if (resultCode == RESULT_OK) {
        try {
            if (requestCode == 200) {
                Uri imageUri = data.getData();
                sendImage(imageUri);
            } 
        }
        catch (Exception e) {

        }
    }else{
        Toast.makeText(this, "Cancelled", Toast.LENGTH_SHORT).show();
    }


}

private void sendImage(Uri imageUri){
UploadTask uploadTask = storageReference.putFile(imageUri);

    uploadTask.addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception exception) {
            // Handle unsuccessful uploads
        }
    }).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

        }
    });
}

Upload photo to Firebase Storage

1 Answers1