[embedyt] https://www.youtube.com/watch?v=0B471wsJ_RY[/embedyt]
Links & DependenciesImageAdapter.javaactivity_images.xmlimage_item.xmlUpload.javaMainActivity.javaAndroidManifest.xmlactivity_main.xml
package com.codinginflow.firebaseuploadexample;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.squareup.picasso.Picasso;

import java.util.List;


public class ImageAdapter extends RecyclerView.Adapter<ImageAdapter.ImageViewHolder> {
    private Context mContext;
    private List<Upload> mUploads;

    public ImageAdapter(Context context, List<Upload> uploads) {
        mContext = context;
        mUploads = uploads;
    }

    @Override
    public ImageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(mContext).inflate(R.layout.image_item, parent, false);
        return new ImageViewHolder(v);
    }

    @Override
    public void onBindViewHolder(ImageViewHolder holder, int position) {
        Upload uploadCurrent = mUploads.get(position);
        holder.textViewName.setText(uploadCurrent.getName());
        Picasso.with(mContext)
                .load(uploadCurrent.getImageUrl())
                .fit()
                .centerCrop()
                .into(holder.imageView);
    }

    @Override
    public int getItemCount() {
        return mUploads.size();
    }

    public class ImageViewHolder extends RecyclerView.ViewHolder {
        public TextView textViewName;
        public ImageView imageView;

        public ImageViewHolder(View itemView) {
            super(itemView);

            textViewName = itemView.findViewById(R.id.text_view_name);
            imageView = itemView.findViewById(R.id.image_view_upload);
        }
    }
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.codinginflow.firebaseuploadexample.ImagesActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:id="@+id/text_view_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:layout_marginBottom="8dp"
            android:layout_marginTop="8dp"
            android:text="Name"
            android:textColor="@android:color/black"
            android:textSize="20sp" />

        <ImageView
            android:id="@+id/image_view_upload"
            android:layout_width="match_parent"
            android:layout_height="200dp" />

    </LinearLayout>

</android.support.v7.widget.CardView>
package com.codinginflow.firebaseuploadexample;

public class Upload {
    private String mName;
    private String mImageUrl;

    public Upload() {
        //empty constructor needed
    }

    public Upload(String name, String imageUrl) {
        if (name.trim().equals("")) {
            name = "No Name";
        }

        mName = name;
        mImageUrl = imageUrl;
    }

    public String getName() {
        return mName;
    }

    public void setName(String name) {
        mName = name;
    }

    public String getImageUrl() {
        return mImageUrl;
    }

    public void setImageUrl(String imageUrl) {
        mImageUrl = imageUrl;
    }
}
package com.codinginflow.firebaseuploadexample;

import android.content.ContentResolver;
import android.content.Intent;
import android.net.Uri;
import android.os.Handler;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
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.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.OnProgressListener;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.StorageTask;
import com.google.firebase.storage.UploadTask;
import com.squareup.picasso.Picasso;

public class MainActivity extends AppCompatActivity {

    private static final int PICK_IMAGE_REQUEST = 1;

    private Button mButtonChooseImage;
    private Button mButtonUpload;
    private TextView mTextViewShowUploads;
    private EditText mEditTextFileName;
    private ImageView mImageView;
    private ProgressBar mProgressBar;

    private Uri mImageUri;

    private StorageReference mStorageRef;
    private DatabaseReference mDatabaseRef;

    private StorageTask mUploadTask;

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

        mButtonChooseImage = findViewById(R.id.button_choose_image);
        mButtonUpload = findViewById(R.id.button_upload);
        mTextViewShowUploads = findViewById(R.id.text_view_show_uploads);
        mEditTextFileName = findViewById(R.id.edit_text_file_name);
        mImageView = findViewById(R.id.image_view);
        mProgressBar = findViewById(R.id.progress_bar);

        mStorageRef = FirebaseStorage.getInstance().getReference("uploads");
        mDatabaseRef = FirebaseDatabase.getInstance().getReference("uploads");

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

        mButtonUpload.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mUploadTask != null && mUploadTask.isInProgress()) {
                    Toast.makeText(MainActivity.this, "Upload in progress", Toast.LENGTH_SHORT).show();
                } else {
                    uploadFile();
                }
            }
        });

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

    private void openFileChooser() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, PICK_IMAGE_REQUEST);
    }

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

        if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK
                && data != null && data.getData() != null) {
            mImageUri = data.getData();

            Picasso.with(this).load(mImageUri).into(mImageView);
        }
    }

    private String getFileExtension(Uri uri) {
        ContentResolver cR = getContentResolver();
        MimeTypeMap mime = MimeTypeMap.getSingleton();
        return mime.getExtensionFromMimeType(cR.getType(uri));
    }

    private void uploadFile() {
        if (mImageUri != null) {
            StorageReference fileReference = mStorageRef.child(System.currentTimeMillis()
                    + "." + getFileExtension(mImageUri));

            mUploadTask = fileReference.putFile(mImageUri)
                    .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                        @Override
                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                            Handler handler = new Handler();
                            handler.postDelayed(new Runnable() {
                                @Override
                                public void run() {
                                    mProgressBar.setProgress(0);
                                }
                            }, 500);

                            Toast.makeText(MainActivity.this, "Upload successful", Toast.LENGTH_LONG).show();
                            Upload upload = new Upload(mEditTextFileName.getText().toString().trim(),
                                    taskSnapshot.getDownloadUrl().toString());
                            String uploadId = mDatabaseRef.push().getKey();
                            mDatabaseRef.child(uploadId).setValue(upload);
                        }
                    })
                    .addOnFailureListener(new OnFailureListener() {
                        @Override
                        public void onFailure(@NonNull Exception e) {
                            Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    })
                    .addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
                        @Override
                        public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                            double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                            mProgressBar.setProgress((int) progress);
                        }
                    });
        } else {
            Toast.makeText(this, "No file selected", Toast.LENGTH_SHORT).show();
        }
    }

    private void openImagesActivity() {
        Intent intent = new Intent(this, ImagesActivity.class);
        startActivity(intent);
    }
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.codinginflow.firebaseuploadexample">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".ImagesActivity"></activity>
    </application>

</manifest>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context="com.codinginflow.firebaseuploadexample.MainActivity">

    <Button
        android:id="@+id/button_choose_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Choose file" />

    <EditText
        android:id="@+id/edit_text_file_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_toEndOf="@+id/button_choose_image"
        android:hint="Enter file name" />

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/progress_bar"
        android:layout_below="@id/edit_text_file_name"
        android:layout_marginTop="16dp" />

    <ProgressBar
        android:id="@+id/progress_bar"
        style="@style/Widget.AppCompat.ProgressBar.Horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/button_upload"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="16dp" />

    <Button
        android:id="@+id/button_upload"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="Upload" />

    <TextView
        android:id="@+id/text_view_show_uploads"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/button_upload"
        android:layout_alignTop="@+id/button_upload"
        android:layout_marginStart="25dp"
        android:layout_toEndOf="@+id/button_upload"
        android:gravity="center"
        android:text="Show Uploads"
        android:textSize="16sp" />

</RelativeLayout>