Deleting Room entry from RecyclerView - android-studio

Question

I am new to programming and I followed this tutorial to create a RecyclerView making use of an adapter. I have no idea how to use the delete function from my Dao in relation to the ImageButton. I have next to each entry. Also, this is my first app, so please be gracious when you see things like ".allowMainThreadQueries".
Activity with recyclerview:
public class DatabaseActivity extends AppCompatActivity {
RecyclerView recyclerView;
RecyclerView.Adapter adapter;
FloatingActionButton fab;
ImageButton delete;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_database);
recyclerView = findViewById(R.id.recycler_view);
AppDatabase db = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, "production").allowMainThreadQueries().build();
final List<Student> students = db.studentDao().getAllUsers();
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new StudentAdapter(students);
recyclerView.setAdapter(adapter);
fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(DatabaseActivity.this, DatabaseAddActivity.class));
}
});
}
}
Adapter:
class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.ViewHolder> {
List<Student> students;
public StudentAdapter(List<Student> students) {
this.students = students;
}
#Override
public StudentAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.student_row, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(StudentAdapter.ViewHolder holder, int position) {
holder.first_name.setText(students.get(position).getFirstName());
holder.last_name.setText(students.get(position).getLastName());
holder.email.setText(students.get(position).getEmail());
}
//See how many items need to be displayed
#Override
public int getItemCount() {
return students.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView first_name;
public TextView last_name;
public TextView email;
public ImageButton delete;
//What we are showing in the viewholder
public ViewHolder(View itemView) {
super(itemView);
first_name = itemView.findViewById(R.id.first_name);
last_name = itemView.findViewById(R.id.last_name);
email = itemView.findViewById(R.id.email);
delete = itemView.findViewById(R.id.delete);
}
}
}
Dao:
#Dao
public interface StudentDao {
#Query("SELECT * FROM student ")
List<Student> getAllUsers();
#Query("SELECT * FROM student WHERE monday = 1")
List<Student> getMonday();
#Query("SELECT * FROM student WHERE tuesday = 1")
List<Student> getTuesday();
#Query("SELECT * FROM student WHERE wednesday = 1")
List<Student> getWednesday();
#Query("SELECT * FROM student WHERE thursday = 1")
List<Student> getThursday();
#Query("SELECT * FROM student WHERE friday = 1")
List<Student> getFriday();
#Insert
void insertAll(Student... students);
#Delete
void delete(Student student);
#Update
void updateStudent(Student student);
}
Student Add:
public class DatabaseAddActivity extends AppCompatActivity {
//Calling needed resources
EditText firstName;
EditText lastName;
EditText email;
Button button;
CheckBox monday, tuesday, wednesday, thursday, friday;
//Defining which view.xml file to use
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_database_add);
//Using resources to find using .xml setup
firstName = findViewById(R.id.first_name);
lastName = findViewById(R.id.last_name);
email = findViewById(R.id.email);
monday = findViewById(R.id.monday_switch);
tuesday = findViewById(R.id.tuesday_switch);
wednesday = findViewById(R.id.wednesday_switch);
thursday = findViewById(R.id.thursday_switch);
friday = findViewById(R.id.friday_switch);
button = findViewById(R.id.button_add);
//What happens when button is pressed
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
AppDatabase db = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, "production").allowMainThreadQueries().build();
Boolean mondayState = monday.isChecked();
Boolean tuesdayState = tuesday.isChecked();
Boolean wednesdayState = wednesday.isChecked();
Boolean thursdayState = thursday.isChecked();
Boolean fridayState = friday.isChecked();
Student student = new Student(firstName.getText().toString(), lastName.getText().toString(), email.getText().toString(), mondayState, tuesdayState, wednesdayState, thursdayState, fridayState);
db.studentDao().insertAll(student);
startActivity(new Intent(DatabaseAddActivity.this,DatabaseActivity.class));
}
});
}
}

Answer 1

In DatabaseActivity:
adapter = new StudentAdapter(db, students);
UPDATED
In your Adapter class:
AppDatabase db;
List<Student> students;
public StudentAdapter(AppDatabase db, List<Student> students) {
this.db = db;
this.students = students;
}
#Override
public void onBindViewHolder(StudentAdapter.ViewHolder holder, int position) {
Student student = students.get(position);
holder.first_name.setText(students.get(position).getFirstName());
holder.last_name.setText(students.get(position).getLastName());
holder.email.setText(students.get(position).getEmail());
holder.delete.setOnClickListener.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
db.delete(student);
students.remove(student);
notifyItemRemoved(position);
}
});
}