Threaded example

app/src/main/java/com/coldlightalchemist/notesapp/MainActivity.java

@@ -1,5 +1,6 @@
 package com.coldlightalchemist.notesapp;
 
+import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 
@@ -18,8 +19,11 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import com.coldlightalchemist.notesapp.db.NoteDB;
+import com.coldlightalchemist.notesapp.db.entities.Note;
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
 
+import java.util.List;
+
 public class MainActivity extends AppCompatActivity {
     private NoteDB db;
 
@@ -59,13 +63,14 @@ public class MainActivity extends AppCompatActivity {
             startActivity(newNoteIntent);
         });
 
-        if (db.noteDAO().getAll().isEmpty()) {
+        NoteDB.execute(() -> {
-            noNotesText.setVisibility(VISIBLE);
+            List<Note> notes = db.noteDAO().getAll();
-            notesRecyclerView.setVisibility(View.GONE);
+
-        } else {
+            NoteDB.getMainLoopHandler().post(() -> {
-            noNotesText.setVisibility(View.GONE);
+                noNotesText.setVisibility(notes.isEmpty() ? VISIBLE : GONE);
-            notesRecyclerView.setVisibility(VISIBLE);
+                notesRecyclerView.setVisibility(notes.isEmpty() ? GONE : VISIBLE);
-        }
+            });
+        });
     }
 
     @Override

app/src/main/java/com/coldlightalchemist/notesapp/NewNote.java

@@ -67,12 +67,23 @@ public class NewNote extends AppCompatActivity {
             note.noteContent = newNoteContent.getText().toString();
 
             if(noteWasNull) {
-                NoteDB.getDB(getApplicationContext()).noteDAO().insertAll(note);
+                NoteDB.execute(() -> {
-            } else {
+                    NoteDB.getDB().noteDAO().insertAll(note);
-                NoteDB.getDB(getApplicationContext()).noteDAO().update(note);
-            }
 
-            finish();
+                    NoteDB.getMainLoopHandler().post(() -> {
+                        finish();
+                    });
+                });
+            } else {
+                NoteDB.execute(() -> {
+                    NoteDB.getDB().noteDAO().update(note);
+
+                    NoteDB.getMainLoopHandler().post(() -> {
+                        finish();
+                    });
+                });
+
+            }
         });
 
         saveNote.setOnLongClickListener((v) -> {
@@ -82,10 +93,15 @@ public class NewNote extends AppCompatActivity {
                 switch(w) {
                     case DialogInterface.BUTTON_POSITIVE:
                         if(note != null) {
-                            NoteDB.getDB(getApplicationContext()).noteDAO().delete(note);
+                            NoteDB.execute(() -> {
-                        }
+                                NoteDB.getDB().noteDAO().delete(note);
 
-                        finish();
+                                NoteDB.getMainLoopHandler().post(() -> {
+                                    finish();
+                                });
+                            });
+
+                        }
                         break;
                     case DialogInterface.BUTTON_NEGATIVE:
                         break;

app/src/main/java/com/coldlightalchemist/notesapp/NotesRecyclerViewAdapter.java

@@ -1,6 +1,7 @@
 package com.coldlightalchemist.notesapp;
 
 import android.content.Intent;
+import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -13,6 +14,8 @@ import com.coldlightalchemist.notesapp.db.NoteDB;
 import com.coldlightalchemist.notesapp.db.dao.NoteDAO;
 import com.coldlightalchemist.notesapp.db.entities.Note;
 
+import java.util.List;
+import java.util.concurrent.ExecutionException;
 import java.util.function.Consumer;
 
 public class NotesRecyclerViewAdapter extends RecyclerView.Adapter<NotesRecyclerViewAdapter.NoteRecyclerViewHolder> {
@@ -66,11 +69,25 @@ public class NotesRecyclerViewAdapter extends RecyclerView.Adapter<NotesRecycler
 
     @Override
     public void onBindViewHolder(@NonNull NoteRecyclerViewHolder holder, int position) {
-        holder.setNote(noteSource.getAll().get(position));
+        NoteDB.execute(() -> {
+            List<Note> notes = noteSource.getAll();
+
+            NoteDB.getMainLoopHandler().post(() -> {
+                holder.setNote(notes.get(position));
+            });
+        });
     }
 
     @Override
     public int getItemCount() {
-        return noteSource.getAll().size();
+        try {
+            return NoteDB.execute(() -> {
+                return NoteDB.getDB().noteDAO().getAll().size();
+            }).get();
+        } catch (ExecutionException | InterruptedException e) {
+            // Cop out
+            Log.d("ITEMCOUNTISSUE", e.toString());
+            return 0;
+        }
     }
 }

app/src/main/java/com/coldlightalchemist/notesapp/db/NoteDB.java

@@ -1,6 +1,8 @@
 package com.coldlightalchemist.notesapp.db;
 
 import android.content.Context;
+import android.os.Handler;
+import android.os.Looper;
 
 import androidx.room.Database;
 import androidx.room.Room;
@@ -9,19 +11,59 @@ import androidx.room.RoomDatabase;
 import com.coldlightalchemist.notesapp.db.dao.NoteDAO;
 import com.coldlightalchemist.notesapp.db.entities.Note;
 
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
 @Database(entities = {Note.class}, version = 1)
 public abstract class NoteDB extends RoomDatabase {
     public abstract NoteDAO noteDAO();
 
     private static NoteDB db;
 
+    private static ExecutorService executorService;
+
+    private static Handler handler;
+
+    public static NoteDB getDB() {
+        if (db == null) {
+            throw new RuntimeException("DB not built");
+        }
+
+        return db;
+    }
+
     public static NoteDB getDB(Context applicationContext) {
         if (db == null) {
             db = Room.databaseBuilder(applicationContext, NoteDB.class, "Notes")
-                    .allowMainThreadQueries() // This is critical to make this whole thing work
                     .build();
         }
 
         return db;
     }
+
+    public static Handler getMainLoopHandler() {
+        if (handler == null) {
+            handler = new Handler(Looper.getMainLooper());
+        }
+
+        return handler;
+    }
+
+    public static void execute(Runnable threadExecute) {
+        if (executorService == null) {
+            executorService = Executors.newSingleThreadExecutor();
+        }
+
+        executorService.execute(threadExecute);
+    }
+
+    public static <T> Future<T> execute(Callable<T> threadExecute) {
+        if (executorService == null) {
+            executorService = Executors.newSingleThreadExecutor();
+        }
+
+        return executorService.submit(threadExecute);
+    }
 }