将图像上传到Firebase-Java

Question

i try to upload an image, unfortunately when i try to click button continue to upload it, the apk always crash, here's the log

It says childName cannot be null or empty

the java

package com.example.firstapplication;

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

import android.content.ContentResolver;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.webkit.MimeTypeMap;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
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.UploadTask;
import com.squareup.picasso.Picasso;

import de.hdodenhof.circleimageview.CircleImageView;

public class Register_two extends AppCompatActivity {

    LinearLayout btn_back;
    Button btn_continue, btn_upload_photo;
    ImageView prof_pic;
    EditText bio, nama_lengkap;

    Uri photo_location;
    Integer photo_max = 1;

    DatabaseReference reference;
    StorageReference storage;

    String USERNAME_KEY = "usernamekey";
    String username_key = "";
    String username_key_new = "";


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

        getUsernameLocal();

        btn_continue = findViewById(R.id.btn_continue);
        btn_back = findViewById(R.id.btn_back);
        btn_upload_photo = findViewById(R.id.btn_upload_photo);
        prof_pic = findViewById(R.id.prof_pic);


        btn_upload_photo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            findPhoto();
            }
        });

        btn_continue.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                //ubah state menjadi loading...
                btn_continue.setEnabled(false);
                btn_continue.setText("Loading...");

                //menyimpan ke Firebase
                reference = FirebaseDatabase.getInstance().getReference().child("Users").child(username_key_new);
                storage = FirebaseStorage.getInstance().getReference().child("Photousers").child(username_key_new);

                //validasi untuk file (apakah ada?)
                if (photo_location != null){
                    final StorageReference storageReference1 =
                            storage.child(System.currentTimeMillis() + "." +
                            getFileExtention(photo_location));

                    storageReference1.putFile(photo_location)
                            .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                        @Override
                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                            storageReference1.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                                @Override
                                public void onSuccess(Uri uri) {
                                    String uri_photo = uri.toString();
                                    reference.getRef().child("url_photo_profile").setValue(uri_photo);
                                    reference.getRef().child("nama_lengkap").setValue(nama_lengkap.getText().toString());
                                    reference.getRef().child("bio").setValue(bio.getText().toString());

                                }
                            }).addOnCompleteListener(new OnCompleteListener<Uri>() {
                                @Override
                                public void onComplete(@NonNull Task<Uri> task) {
                                    //pindah activity
                                    Intent btncontinue = new Intent(Register_two.this,SuccessRegister.class);
                                    startActivity(btncontinue);
                                }
                            });

                            }
                    }).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
                        @Override
                        public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task) {
                            //pindah activity
                           // Intent btncontinue = new Intent(Register_two.this,SuccessRegister.class);
                           // startActivity(btncontinue);
                        }
                    });
                }


            }
        });

        btn_back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent goback = new Intent(Register_two.this,Register_one.class);
                startActivity(goback);
            }
        });

    }

    String getFileExtention(Uri uri){
        ContentResolver contentResolver = getContentResolver();
        MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
        return mimeTypeMap.getExtensionFromMimeType(contentResolver.getType(uri));
    }

    public void findPhoto(){
        Intent pic = new Intent();
        pic.setType("image/*");
        pic.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(pic, photo_max);

    }

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

            if (requestCode == photo_max && resultCode == RESULT_OK && data != null && data.getData() != null)
            {
                photo_location = data.getData();
                Picasso.with(this).load(photo_location).centerCrop().fit().into(prof_pic);

            }
     }
     public void getUsernameLocal(){
         SharedPreferences sharedPreferences = getSharedPreferences(USERNAME_KEY, MODE_PRIVATE);
         username_key_new = sharedPreferences.getString(username_key,"");
     }
}

the error said, i'm passing null into a child in the line 81

storage = FirebaseStorage.getInstance().getReference().child("Photousers").child(username_key_new);

but i dont know what is wrong

Answer 1

Have you ever try this?

And I suggest to make a return string instead making a void method

//Please check what is the identifier of the string in sharedpreferences
//if usernamekey is the identifier then getString("usernamekey","");
public String getUsernameLocal(){
     SharedPreferences sharedPreferences = getSharedPreferences(USERNAME_KEY, MODE_PRIVATE);
     String userKey= sharedPreferences.getString(USERNAME_KEY,"");
     return userKey;
 }

And your reference

storage = FirebaseStorage.getInstance().getReference().child("Photousers").child(getUsernameLocal());