使用Realm和Recycler View的最佳实践?

29

你们有没有使用Realm与RecyclerView的最佳实践?我知道这是一个泛泛的问题,但我在网上找不到任何相关资料。例如,我尝试在行中实现简单的颜色更改时遇到了很多问题。例如,请考虑以下典型用法:

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
   }

由于在互联网上找不到任何内容,我遇到了很多问题。我知道这是因为我不知道如何正确地使用 Realm。但是找到正确的方法本身就是个挑战。我已经阅读了他们所有的文档,但没有结果。

编辑:由于被要求-->而不是说“我有很多与此相关的问题”,请描述您的问题,我们将尝试为您提供解决方案和答案。

因此,我的问题很简单:

我有一个 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;
    }


}

使用以下方式将其放入RealmResults数组中:

RealmResults users = realm.where(RealmUser.class).findAll();

我将我的用户数组传递给了自定义用户适配器:

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. 

}

它具有自定义点击监听器:使用以下方法获取被单击的 RecyclerView 项:

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) {

    }
}

我使用addOnItemTouchListener将其添加到我的recyclerView中:

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);
            }
    }));

2
欢迎来到Stack Overflow!请重新阅读问题,使其更加清晰并删除拼写错误。此外,我们喜欢具体的问题。不要只是说“我有很多问题与[那个]”,而是描述你的问题,我们会尝试提供见解和回答你的困惑之处。 - Kyll
好的,我会编辑我的帖子。 - Anghelut Florin
5个回答

12
0.89.0及以上版本的答案

对于最新版本,您应该使用realm-android-adapters存储库中的RealmRecyclerViewAdapter

版本:

  • 使用1.5.0至2.X

  • 使用2.1.1至4.X

  • 使用3.0.0以上5.X


旧版本的旧答案:

我根据 RealmBaseAdapter 的实现制作了这个 RealmRecyclerViewAdapter

这适用于 v0.89.0 及以上版本

public abstract class RealmRecyclerViewAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
    extends RecyclerView.Adapter<VH> { //put this in `io.realm`

    protected LayoutInflater inflater;
    protected OrderedRealmCollection<T> adapterData;
    protected Context context;
    private final RealmChangeListener listener;

    public RealmRecyclerViewAdapter(Context context, OrderedRealmCollection<T> data) {
        if (context == null) {
            throw new IllegalArgumentException("Context cannot be null");
        }
        this.context = context;
        this.adapterData = data;
        this.inflater = LayoutInflater.from(context);
        this.listener = new RealmChangeListener<RealmResults<T>>() {
            @Override
            public void onChange(RealmResults<T> results) {
                notifyDataSetChanged();
            }
        };

        if (data != null) {
            addListener(data);
        }
    }

    private void addListener(OrderedRealmCollection<T> data) {
        if (data instanceof RealmResults) {
            RealmResults realmResults = (RealmResults) data;
            realmResults.addChangeListener(listener);
        } else if (data instanceof RealmList) {
            RealmList realmList = (RealmList) data;
            realmList.realm.handlerController.addChangeListenerAsWeakReference(listener);
        } else {
            throw new IllegalArgumentException("RealmCollection not supported: " + data.getClass());
        }
    }

    private void removeListener(OrderedRealmCollection<T> data) {
        if (data instanceof RealmResults) {
            RealmResults realmResults = (RealmResults) data;
            realmResults.removeChangeListener(listener);
        } else if (data instanceof RealmList) {
            RealmList realmList = (RealmList) data;
            realmList.realm.handlerController.removeWeakChangeListener(listener);
        } else {
            throw new IllegalArgumentException("RealmCollection not supported: " + data.getClass());
        }
    }

    /**
     * Returns how many items are in the data set.
     *
     * @return the number of items.
     */
    @Override
    public int getItemCount() {
        if (adapterData == null) {
            return 0;
        }
        return adapterData.size();
    }

    /**
     * Get the data item associated with the specified position in the data set.
     *
     * @param position Position of the item whose data we want within the adapter's
     * data set.
     * @return The data at the specified position.
     */
    public T getItem(int position) {
        if (adapterData == null) {
            return null;
        }
        return adapterData.get(position);
    }

    /**
     * Get the row id associated with the specified position in the list. Note that item IDs are not stable so you
     * cannot rely on the item ID being the same after {@link #notifyDataSetChanged()} or
     * {@link #updateData(OrderedRealmCollection)} has been called.
     *
     * @param position The position of the item within the adapter's data set whose row id we want.
     * @return The id of the item at the specified position.
     */
    @Override
    public long getItemId(int position) {
        // TODO: find better solution once we have unique IDs
        return position;
    }

    /**
     * Updates the data associated with the Adapter.
     *
     * Note that RealmResults and RealmLists are "live" views, so they will automatically be updated to reflect the
     * latest changes. This will also trigger {@code notifyDataSetChanged()} to be called on the adapter.
     *
     * This method is therefore only useful if you want to display data based on a new query without replacing the
     * adapter.
     *
     * @param data the new {@link OrderedRealmCollection} to display.
     */
    public void updateData(OrderedRealmCollection<T> data) {
        if (listener != null) {
            if (adapterData != null) {
                removeListener(adapterData);
            }
            if (data != null) {
                addListener(data);
            }
        }

        this.adapterData = data;
        notifyDataSetChanged();
    }
}

这是针对v0.84.0及以上版本,但早于v0.89.0的内容(已更新至v0.87.5):
public abstract class RealmRecyclerViewAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
        extends RecyclerView.Adapter<VH> { //put this in `io.realm`
    protected LayoutInflater inflater;
    protected RealmResults<T> realmResults;
    protected Context context;
    private final RealmChangeListener listener;

    public RealmRecyclerViewAdapter(Context context, RealmResults<T> realmResults, boolean automaticUpdate) {
        if (context == null) {
            throw new IllegalArgumentException("Context cannot be null");
        }
        this.context = context;
        this.realmResults = realmResults;
        this.inflater = LayoutInflater.from(context);
        this.listener = (!automaticUpdate) ? null : new RealmChangeListener() {
            @Override
            public void onChange() {
                notifyDataSetChanged();
            }
        };

        if (listener != null && realmResults != null) {
            realmResults.realm.handlerController.addChangeListenerAsWeakReference(listener);
        }
    }

    /**
     * Returns how many items are in the data set.
     *
     * @return count of items.
     */
    @Override
    public int getItemCount() {
        if (realmResults == null) {
            return 0;
        }
        return realmResults.size();
    }

    /**
     * Returns the item associated with the specified position.
     *
     * @param i index of item whose data we want.
     * @return the item at the specified position.
     */
    public T getItem(int i) {
        if (realmResults == null) {
            return null;
        }
        return realmResults.get(i);
    }

    /**
     * Returns the current ID for an item. Note that item IDs are not stable so you cannot rely on the item ID being the
     * same after {@link #notifyDataSetChanged()} or {@link #updateRealmResults(RealmResults)} has been called.
     *
     * @param i index of item in the adapter.
     * @return current item ID.
     */
    @Override
    public long getItemId(int i) {
        // TODO: find better solution once we have unique IDs
        return i;
    }

    /**
     * Updates the RealmResults associated to the Adapter. Useful when the query has been changed.
     * If the query does not change you might consider using the automaticUpdate feature.
     *
     * @param queryResults the new RealmResults coming from the new query.
     */
    public void updateRealmResults(RealmResults<T> queryResults) {
        if (listener != null) {
            // Making sure that Adapter is refreshed correctly if new RealmResults come from another Realm
            if (this.realmResults != null) {
                this.realmResults.realm.removeChangeListener(listener);
            }
            if (queryResults != null) {
                queryResults.realm.addChangeListener(listener);
            }
        }

        this.realmResults = queryResults;
        notifyDataSetChanged();
    }

    public void addChangeListenerAsWeakReference(RealmChangeListener realmChangeListener) {
        if(realmResults != null) {
            realmResults.realm.handlerController.addChangeListenerAsWeakReference(realmChangeListener);
        }
    }
}

这是针对早于0.84.0版本的:
public abstract class RealmRecyclerViewAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
        extends RecyclerView.Adapter<VH> { //put this in `io.realm`
    protected LayoutInflater inflater;
    protected RealmResults<T> realmResults;
    protected Context context;

    private final RealmChangeListener listener;

    public RealmRecyclerViewAdapter(Context context, RealmResults<T> realmResults, boolean automaticUpdate) {
        if(context == null) {
            throw new IllegalArgumentException("Context cannot be null");
        }
        this.context = context;
        this.realmResults = realmResults;
        this.inflater = LayoutInflater.from(context);
        this.listener = (!automaticUpdate) ? null : new RealmChangeListener() {
            @Override
            public void onChange() {
                notifyDataSetChanged();
            }
        };

        if(listener != null && realmResults != null) {
            realmResults.getRealm()
                    .addChangeListener(listener);
        }
    }

    @Override
    public long getItemId(int i) {
        // TODO: find better solution once we have unique IDs
        return i;
    }

    public T getItem(int i) {
        if(realmResults == null) {
            return null;
        }
        return realmResults.get(i);
    }

    public void updateRealmResults(RealmResults<T> queryResults) {
        if(listener != null) {
            // Making sure that Adapter is refreshed correctly if new RealmResults come from another Realm
            if(this.realmResults != null) {
                realmResults.getRealm().removeChangeListener(listener);
            }
            if(queryResults != null) {
                queryResults.getRealm().addChangeListener(listener);
            }
        }

        this.realmResults = queryResults;
        notifyDataSetChanged();
    }

    @Override
    public int getItemCount() {
        if(realmResults == null) {
            return 0;
        }
        return realmResults.size();
    }
}

为什么getRealm()是包保护的? - Vaibhav Gupta
1
@VaibhavGupta 我不知道,但我听说如果你将类命名为io.realm包内的,则根本不需要反射。这是“包”,而不是“私有”! - EpicPandaForce

10

以上一些答案包括反射,更不用说分组的RecyclerView会引起复杂性。它们也不支持添加和删除项目。这是我使用Realm编写的RecyclerView适配器版本,支持分组的RecyclerView,在需要时还可以在任意位置添加和删除项目。

以下是我们的AbstractRealmAdapter,它处理所有低级别的事情,显示标题、页脚、项目,在RealmResults中加载数据,管理项目类型。

import io.realm.Realm;
import io.realm.RealmObject;
import io.realm.RealmResults;

public abstract class AbstractRealmAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
        extends RecyclerView.Adapter<VH> {

    public static final int HEADER_COUNT = 1;
    public static final int FOOTER_COUNT = 1;

    //Our data source
    protected RealmResults<T> mResults;

    public AbstractRealmAdapter(Realm realm) {
        //load data from subclasses
        mResults = loadData(realm);
        notifyDataSetChanged();
    }


    public int getHeaderCount() {
        return hasHeader() ? HEADER_COUNT : 0;
    }

    public int getFooterCount() {
        return hasFooter() ? FOOTER_COUNT : 0;
    }

    public boolean isHeader(int position) {
        if (hasHeader()) {
            return position < HEADER_COUNT;
        } else {
            return false;
        }
    }

    public boolean isFooter(int position) {
        if (hasFooter()) {
            return position >= getCount() + getHeaderCount();
        } else {
            return false;
        }
    }

    @Override
    public long getItemId(int i) {
        return i;
    }


    @Override
    public final int getItemViewType(int position) {
        if (isHeader(position)) {
            return ItemType.HEADER.ordinal();
        } else if (isFooter(position)) {
            return ItemType.FOOTER.ordinal();
        } else {
            return ItemType.ITEM.ordinal();
        }
    }

    /**
     * @param position the position within our adapter inclusive of headers,items and footers
     * @return an item only if it is not a header or a footer, otherwise returns null
     */
    public T getItem(int position) {
        if (!isHeader(position) && !isFooter(position) && !mResults.isEmpty()) {
            return mResults.get(position - getHeaderCount());
        }
        return null;
    }


    @Override
    public final int getItemCount() {
        return getHeaderCount() + getCount() + getFooterCount();
    }

    public final int getCount() {
        return mResults.size();
    }

    public abstract boolean hasHeader();

    public abstract boolean hasFooter();


    public void setData(RealmResults<T> results) {
        mResults = results;
        notifyDataSetChanged();
    }

    protected abstract RealmResults<T> loadData(Realm realm);

    public enum ItemType {
        HEADER, ITEM, FOOTER;
    }
}

为了通过某种方法添加项目或通过滑动删除删除项目,我们有一个扩展程序,形式为AbstractMutableRealmAdapter,如下所示。
import android.support.v7.widget.RecyclerView;

import io.realm.Realm;
import io.realm.RealmObject;

public abstract class AbstractMutableRealmAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
        extends AbstractRealmAdapter<T, VH> implements OnSwipeListener {

    private Realm realm;

    public AbstractMutableRealmAdapter(Realm realm) {
        //call the superclass constructor to load data from subclasses into realmresults
        super(realm);
        this.realm = realm;
    }

    public void add(T item, boolean update) {
        realm.beginTransaction();
        T phraseToWrite = (update == true) ? realm.copyToRealmOrUpdate(item) : realm.copyToRealm(item);
        realm.commitTransaction();
        notifyItemRangeChanged(0, mResults.size());
    }

    @Override
    public final void onSwipe(int position) {
        if (!isHeader(position) && !isFooter(position) && !mResults.isEmpty()) {
            int itemPosition = position - getHeaderCount();
            realm.beginTransaction();
            T item = mResults.get(itemPosition);
            item.removeFromRealm();
            realm.commitTransaction();
            notifyItemRemoved(position);
        }
    }

}

请注意使用 OnSwipeListener 接口,其代码如下:
public interface OnSwipeListener {
    /**
     * @param position the position of the item that was swiped within the RecyclerView
     */
    void onSwipe(int position);
}

这个SwipeListener用于在TouchHelperCallback中执行滑动删除操作,TouchHelperCallback又直接从Realm中删除对象。具体代码如下:
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;

public class TouchHelperCallback extends ItemTouchHelper.Callback {

    private final OnSwipeListener mSwipeListener;

    public TouchHelperCallback(OnSwipeListener adapter) {
        mSwipeListener = adapter;
    }

    /**
     * @return false if you dont want to enable drag else return true
     */
    @Override
    public boolean isLongPressDragEnabled() {
        return false;
    }

    /**
     * @return true of you want to enable swipe in your RecyclerView else return false
     */
    @Override
    public boolean isItemViewSwipeEnabled() {
        return true;
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        //We want to let the person swipe to the right on devices that run LTR and let the person swipe from right to left on devices that run RTL
        int swipeFlags = ItemTouchHelper.END;
        return makeMovementFlags(0, swipeFlags);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
                          RecyclerView.ViewHolder target) {
        return false;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        mSwipeListener.onSwipe(viewHolder.getAdapterPosition());
    }
}

完整的实现演示可以在此处查看:https://github.com/slidenerd/SpamWordList/tree/spamphraser_with_realmresults_base,欢迎提出任何改进意见。
我用 notifyDataSetChanged 替换了 notifyXXX 方法,RealmResults 对象是实时对象,这意味着当数据更新时它们会自动更改。我尝试调用 notifyXXX 方法,但它们导致 RecyclerView 不一致异常。我很清楚 notifyDataSetChanged() 会影响动画效果,将为您提供一个解决不一致错误并同时提供良好适配器体验的解决方案。

非常晚才加入,但演示已经移动到:https://github.com/canadianeagle/SpamWordList - Carl Smith

4

现在,随着 Realm 0.88.2 的推出,我们可以使用比每次使用 notifyDataSetChanged() 更精确的方式更新 RecyclerView 的适配器。这可以通过使用新的能力创建自定义方法来实现。

在将要与 recycler adapter 一起使用的 realm 对象中覆盖 equals 方法就足够了。(实际上你不需要覆盖 equals...但是你可能会发现当你期望它们相等时,realm 对象并不相等。这会导致运行 diff 后不必要的 recyclerview 更新)

然后将 Google 的 java-diff-utils 添加到您的 gradle 依赖项中

    compile 'com.googlecode.java-diff-utils:diffutils:1.3.0'

使用这个RealmRecyclerViewAdapter实现时,在开始时会制作一个realmResults的副本,并在每次更改时与未来更改进行比较。检测到的更改将用于适当地更新RecyclerView。
public abstract class RealmRecyclerViewAdapter<T extends RealmObject, VH extends RecyclerView.ViewHolder>
    extends RecyclerView.Adapter<VH> {


protected RealmResults<T> realmResults;
protected List<T> lastCopyOfRealmResults;
int maxDepth = 0;

private RealmChangeListener realmResultsListener;
Realm realm;

public RealmRecyclerViewAdapter(RealmResults<T> realmResults, boolean automaticUpdate) {
    this(realmResults, automaticUpdate, 0);
}

/**
 *
 * @param realmResults
 * @param automaticUpdate
 * @param maxDepth limit of the deep copy when copying realmResults. All references after this depth will be {@code null}. Starting depth is {@code 0}.
 *                 A copy of realmResults is made at start, and on every change to compare against future changes. Detected changes are used to update
 *                 the RecyclerView as appropriate
 */
public RealmRecyclerViewAdapter(RealmResults<T> realmResults, boolean automaticUpdate, int maxDepth) {

    this.realmResultsListener = (!automaticUpdate) ? null : getRealmResultsChangeListener();

    if (realmResultsListener != null && realmResults != null) {
        realmResults.addChangeListener(realmResultsListener);
    }
    this.realmResults = realmResults;
    realm = Realm.getDefaultInstance();
    this.maxDepth = maxDepth;

    lastCopyOfRealmResults = realm.copyFromRealm(realmResults, this.maxDepth);
}



@Override
public int getItemCount() {
    return realmResults != null ? realmResults.size() : 0;
}

/**
 * Make sure this is called before a view is destroyed to avoid memory leaks do to the listeners.
 * Do this by calling setAdapter(null) on your RecyclerView
 * @param recyclerView
 */
@Override
public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
    super.onDetachedFromRecyclerView(recyclerView);
    if (realmResultsListener != null) {
        if (realmResults != null) {
            realmResults.removeChangeListener(realmResultsListener);
        }
    }
    realm.close();
}

/**
 * Update the RealmResults associated with the Adapter. Useful when the query has been changed.
 * If the query does not change you might consider using the automaticUpdate feature.
 *
 * @param queryResults the new RealmResults coming from the new query.
 * @param maxDepth limit of the deep copy when copying realmResults. All references after this depth will be {@code null}. Starting depth is {@code 0}.
 *                 A copy of realmResults is made at start, and on every change to compare against future changes. Detected changes are used to update
 *                 the RecyclerView as appropriate
 */
public void updateRealmResults(RealmResults<T> queryResults, int maxDepth) {
    if (realmResultsListener != null) {
        if (realmResults != null) {
            realmResults.removeChangeListener(realmResultsListener);
        }
    }

    realmResults = queryResults;
    if (realmResults != null && realmResultsListener !=null) {
        realmResults.addChangeListener(realmResultsListener);
    }
    this.maxDepth = maxDepth;
    lastCopyOfRealmResults = realm.copyFromRealm(realmResults,this.maxDepth);

    notifyDataSetChanged();
}

public T getItem(int position) {
    return realmResults.get(position);
}

public int getRealmResultsSize(){
    return realmResults.size();
}


private RealmChangeListener getRealmResultsChangeListener() {
    return new RealmChangeListener<RealmResults<T>>() {
        @Override
        public void onChange(RealmResults<T> element) {
            if (lastCopyOfRealmResults != null && !lastCopyOfRealmResults.isEmpty()) {
                if (realmResults.isEmpty()) {
                    // If the list is now empty, just notify the recyclerView of the change.
                    lastCopyOfRealmResults = realm.copyFromRealm(realmResults,maxDepth);
                    notifyDataSetChanged();
                    return;
                }
                Patch patch = DiffUtils.diff(lastCopyOfRealmResults, realmResults);
                List<Delta> deltas = patch.getDeltas();
                lastCopyOfRealmResults = realm.copyFromRealm(realmResults,maxDepth);
                if (!deltas.isEmpty()) {
                    List<Delta> deleteDeltas = new ArrayList<>();
                    List<Delta> insertDeltas = new ArrayList<>();
                    for (final Delta delta : deltas) {
                        switch (delta.getType()){
                            case DELETE:
                                deleteDeltas.add(delta);
                                break;
                            case INSERT:
                                insertDeltas.add(delta);
                                break;
                            case CHANGE:
                                notifyItemRangeChanged(
                                        delta.getRevised().getPosition(),
                                        delta.getRevised().size());
                                break;
                        }
                    }
                    for (final Delta delta : deleteDeltas) {
                        notifyItemRangeRemoved(
                                delta.getOriginal().getPosition(),
                                delta.getOriginal().size());
                    }
                    //item's should be removed before insertions are performed
                    for (final Delta delta : insertDeltas) {
                        notifyItemRangeInserted(
                                delta.getRevised().getPosition(),
                                delta.getRevised().size());
                    }
                }
            } else {
                notifyDataSetChanged();
                lastCopyOfRealmResults = realm.copyFromRealm(realmResults,maxDepth);
            }
        }
    };
}

}

这解决了一个非常大的问题,当在另一个线程上进行realm更改时。所解决的问题将是“对象无效,是否被另一个线程删除”的错误,使用不同的库,该问题得到了很好地解决。 - TheAnimatrix

1
你的帖子甚至没有真正的问题。
你看过这篇文章吗:http://gradlewhy.ghost.io/realm-results-with-recyclerview/
不确定为什么你不只是在适配器中使用ArrayList,并将所有元素从RealmResult添加到该列表中。有人能解释一下为什么博客文章中的解决方案会更好吗?

感谢您的博客文章。 - user1480139
8
为什么不在适配器中使用ArrayList,并将所有元素从RealmResult添加到该列表中?因为那样做会很慢,并且抛弃了使用REALM的全部意义! - EpicPandaForce
2
查询是惰性的,这意味着只有在需要时才执行RealmQuery,并逐个获取元素。这样做的原因是因为您不会一次性获取所有20000个查询结果,这非常有用。 - EpicPandaForce

0

Thorben Primke实现Realm插件是处理带有Realm数据库的Recycler View应用程序的非常方便的方法。他的github上有很好的示例可以供参考。

我将在此处包含我的示例,以便您有一个参考。首先,修改您的项目构建gradle以使用jitpack.io:

allprojects {
repositories {
    jcenter()
    maven { url "https://jitpack.io" }
}

然后将您的模块 gradle 指向库:(注意,检查最新版本)

dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.github.thorbenprimke:realm-recyclerview:0.9.20'

使用RealmRecyclerView创建一个可重复使用视图的XML布局:
    <?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"

    android:id="@+id/swipeRefreshLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <co.moonmonkeylabs.realmrecyclerview.RealmRecyclerView
        android:id="@+id/realm_recycle_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:rrvIsRefreshable="true"
        app:rrvEmptyLayoutId="@layout/empty_view"
        app:rrvLayoutType="LinearLayout"
        app:rrvSwipeToDelete="true"
        />
</RelativeLayout>

现在在你的 RealmRecycler Fragment 中获取一个 RealmObjects 查询结果,填充并定义一个 Primke RealmAdapter:

 Log.i(TAG, " Obtain Filtered List");
    final RealmResults <Session> realmResults = queryD.findAllSorted(
            "sessionId", Sort.DESCENDING);

    Log.i(TAG, " Inflate realm List");
    View view = inflater.inflate(R.layout.realm_card_recycler2, null);

    Log.i(TAG, " Define and configure SessionRealmAdapter");
    SessionRealmAdapter sessionRealmAdapter =
            new SessionRealmAdapter(getActivity(), realmResults, true,    true);`enter code here`
    RealmRecyclerView realmRecyclerView =
            (RealmRecyclerView)  view.findViewById(R.id.realm_recycle_view);
    realmRecyclerView.setAdapter(sessionRealmAdapter);

最后,为您想要的操作配置Realm适配器。我已经为点击动作设置了一些内容,并打开了滑动删除以删除Realm记录。

      public class SessionRealmAdapter
          extends RealmBasedRecyclerViewAdapter<Session, SessionRealmAdapter.ViewHolder> {

      public class ViewHolder extends RealmViewHolder {

          public TextView sessionTextView;
          public ViewHolder(FrameLayout container) {
              super(container);
              this.sessionTextView = (TextView) container.findViewById(R.id.session_text_view);
          }
      }

      public SessionRealmAdapter(
              Context context,
              RealmResults<Session> realmResults,
              boolean automaticUpdate,
              boolean animateResults) {
          super(context, realmResults, automaticUpdate, animateResults);
      }

      @Override
      public ViewHolder onCreateRealmViewHolder(ViewGroup viewGroup, int viewType) {
          View v = inflater.inflate(R.layout.session_simple_view, viewGroup, false);
          return new ViewHolder((FrameLayout) v);
      }

      @Override
      public void onBindRealmViewHolder(ViewHolder viewHolder, int position) {
          final Session singleSession = realmResults.get(position);
          viewHolder.sessionTextView.setText(singleSession.gettMethod());
          viewHolder.sessionTextView.setOnClickListener(
                  new View.OnClickListener(){

                      @Override
                      public void onClick(View v){
                          selectSession(singleSession);
                          showMessage(" Selected "+singleSession.gettMethod());
                      }
                  }
          );
          viewHolder.sessionTextView.setOnLongClickListener(
                  new View.OnLongClickListener(){

                      @Override
                      public boolean onLongClick(View v){
                            showInformationDialog(singleSession);
                            showMessage("Long click selected for "
                                    +singleSession.getSessionTitle());
                            return true;
                      }
                  }
          );
      }
  }

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