Add list/RoomUserAdapter.java

app/src/main/java/chat/rocket/android/layouthelper/chatroom/list/RoomUserAdapter.java

+package chat.rocket.android.layouthelper.chatroom.list;
+
+import android.content.Context;
+import android.support.v7.widget.RecyclerView;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.List;
+import chat.rocket.android.R;
+import chat.rocket.android.helper.TextUtils;
+import chat.rocket.android.widget.AbsoluteUrl;
+import chat.rocket.core.models.User;
+import chat.rocket.persistence.realm.models.ddp.RealmUser;
+import chat.rocket.persistence.realm.RealmHelper;
+import chat.rocket.android.renderer.UserRenderer;
+
+/**
+ * RecyclerView adapter for UsersOfRooms.
+ */
+public class RoomUserAdapter extends RecyclerView.Adapter<RoomUserViewHolder> {
+
+  private final Context context;
+  private final LayoutInflater inflater;
+  private final RealmHelper realmHelper;
+  private final AbsoluteUrl absoluteUrl;
+  private final String hostname;
+  private List<String> usernames;
+
+  /**
+   * Constructor with required parameters.
+   */
+  public RoomUserAdapter(Context context, RealmHelper realmHelper, AbsoluteUrl absoluteUrl, String hostname) {
+    this.context = context;
+    this.inflater = LayoutInflater.from(context);
+    this.realmHelper = realmHelper;
+    this.absoluteUrl = absoluteUrl;
+    this.hostname = hostname;
+  }
+
+  @Override
+  public RoomUserViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+    View itemView = inflater.inflate(R.layout.listitem_room_user, parent, false);
+    return new RoomUserViewHolder(itemView);
+  }
+
+  @Override
+  public void onBindViewHolder(RoomUserViewHolder holder, int position) {
+    String username = usernames.get(position);
+    if (TextUtils.isEmpty(username)) {
+      return;
+    }
+
+    RealmUser realmUser = realmHelper.executeTransactionForRead(realm ->
+        realm.where(RealmUser.class).equalTo(RealmUser.USERNAME, username).findFirst());
+    if (realmUser == null) {
+      User user = User.builder()
+          .setId("some-local-is")
+          .setUsername(username)
+          .setUtcOffset(0)
+          .build();
+
+      UserRenderer userRenderer = new UserRenderer(user);
+      userRenderer.showAvatar(holder.avatar, hostname);
+      userRenderer.showUsername(holder.username);
+    } else {
+      UserRenderer userRenderer = new UserRenderer(realmUser.asUser());
+      userRenderer.showAvatar(holder.avatar, hostname);
+      userRenderer.showUsername(holder.username);
+      userRenderer.showStatusColor(holder.status);
+    }
+  }
+
+  @Override
+  public int getItemCount() {
+    return usernames != null ? usernames.size() : 0;
+  }
+
+  public void setUsernames(List<String> usernames) {
+    this.usernames = usernames;
+    notifyDataSetChanged();
+  }
+}