Do you guys have any best practices regarding using realm with a recyclerview ?
I know it's generic question but I found nothing on it on the internet. For example I run into a lot of troubles trying to implement a simple color change on a row . For example consider this typical usage:
public class User extends RealmObject {
@PrimaryKey
String name;
boolean isSelected;
...
constructor, getter and setters
}
public class UserAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private RealmResults<User> users;
public UserAdapter(RealmResults<User> users) {
this.users = users;
}
...
public void markAsSelected(int position){
// get the old selected user and deselect it
notifyItemChanged(? how do i get the position given my User has no index ?);
// mark as selected the new user at position
}
I ran into a lot of issues since I couldn't find anything on the internet. I know this is because I don't know how to properly use realm. But finding the right way is a struggle in itself . I read all their documentation but to no avail.
EDIT : Since I was asked to --> Instead of saying "I have a bunch of issues with [that]", describe your issue(s) and we'll try to provide insights and answers to your incomprehensions.
So my problem is simple :
I have a RealmUser :
public class RealmUser extends RealmObject {
@PrimaryKey
private String key;
private String name;
private boolean isSelected;
private boolean editMode;
private RealmList<RealmItemList> lists;
public RealmUser() {}
public RealmUser(String name, RealmList<RealmItemList> lists, boolean isSelected , boolean editMode) {
this.key = UUID.randomUUID().toString();
this.name = name;
this.isSelected = isSelected;
this.editMode = editMode;
if (lists ==null){
this.lists = new RealmList<RealmItemList>();
}else{
this.lists = lists;
}
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public boolean isSelected() {
return isSelected;
}
public void setSelected(boolean isSelected) {
this.isSelected = isSelected;
}
public boolean isEditMode() {
return editMode;
}
public void setEditMode(boolean editMode) {
this.editMode = editMode;
}
public RealmList<RealmItemList> getLists() {
return lists;
}
public void setLists(RealmList<RealmItemList> lists) {
this.lists = lists;
}
}
Which I put in a RealmResults array using :
RealmResults users = realm.where(RealmUser.class).findAll();
I pass my user array to my custom user adapter :
public class UserAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private RealmResults<RealmUser> users;
public UserAdapter(RealmResults<RealmUser> users) {
this.users = users;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
if(viewType == 1){
View v = inflater.inflate(R.layout.detail_user, parent, false);
return new UserHolder(v);
}else if(viewType == 2){
View v = inflater.inflate(R.layout.edit_user, parent, false);
return new editUserHolder(v);
}else {
return null;
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
RealmUser user = users.get(position);
String userName = user.getName();
boolean isSelected = user.isSelected();
if (holder instanceof UserHolder ){
UserHolder uHolder = (UserHolder) holder;
uHolder.userText.setText(userName);
if (isSelected){
uHolder.userContainer.setBackgroundColor(Color.parseColor("#607D8B"));
}
}else if(holder instanceof editUserHolder){
editUserHolder eUserHolder = (editUserHolder) holder;
eUserHolder.userEditContainer.setBackgroundColor(Color.parseColor("#eeeeee"));
}
}
@Override
public int getItemViewType(int position) {
RealmUser user = users.get(position);
if (user.isEditMode()){
return 2;
}else {
return 1;
}
}
@Override
public int getItemCount() {
return users.size();
}
public void markAsSelected(int position, DrawerLayout mDrawerLayout , Toolbar toolbar, Realm realm){
// Here is my problem : How do I get the already selected user asuming there is one in my db and notify the UI that I changed that item.
}
That has a custom click Listener : that gets recyclerview item that was clicked using :
public class UserClickListener implements RecyclerView.OnItemTouchListener{
public static interface OnItemClickListener{
public void onItemClick(View v, int position);
}
private OnItemClickListener mListener;
private GestureDetector mGestureDetector;
public UserClickListener(Context context, final RecyclerView recyclerView, OnItemClickListener listener)
{
mListener = listener;
mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
View childView = recyclerView.findChildViewUnder(e.getX(), e.getY());
if(childView != null && mListener != null)
{
mListener.onItemClick(childView, recyclerView.getChildPosition(childView));
return true;
}
return false;
}
});
}
@Override
public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) {
View childView = view.findChildViewUnder(e.getX(), e.getY());
if(childView != null && mListener != null && mGestureDetector.onTouchEvent(e))
{
mListener.onItemClick(childView, view.getChildPosition(childView));
}
return false;
}
@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
}
}
Which I add to my recyclerView with addOnItemTouchListener :
mListRecycler.addOnItemTouchListener(new UserClickListener(getActivity(), mListRecycler, new UserClickListener.OnItemClickListener(){
@Override
public void onItemClick(View view, int position)
{
UserAdapter myadapter = (UserAdapter) mListRecycler.getAdapter();
myadapter.markAsSelected(position, mDrawerLayout , mToolbar, realm);
}
}));
See Question&Answers more detail:
os 
