填写列表（正确填写为我的日志显示）后，适配器不显示项目。我不知道为什么。
我读到最好使用特殊的“通知...”方法，而不是像NULL这样的adapter.notifyDataSetChanged() ...我已经完成了（我希望正确），但它仍然显示没有。我希望你能帮助我......
（从Obejcts调用并插入列表工作正常......运行应用程序后我没有收到任何错误，只是项目没有显示）
数据模型（用户）
adapter.notifyItemInserted(position)适配器
public class User {
public String name;
public String lastMessage;
public ParseObject image;
//Konstruktor
public User(String name, String lastMessage, ParseObject image) {
this.name = name;
this.lastMessage = lastMessage;
this.image = image;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLastMessage() {
return lastMessage;
}
public void setLastMessage(String lastMessage) {
this.lastMessage = lastMessage;
}
public ParseObject getImage() {
return image;
}
public void setImage(ParseObject image) {
this.image = image;
}
}
UserListActivity
public class UserListAdapter extends SwipeableUltimateViewAdapter<User> {
public UserListAdapter(List<User> items) {
super(items);
}
//iwas internes
@Override
protected int getNormalLayoutResId() {
return DVHolder.layout;
}
//UltimateRecyclerView interaktionen
@Override
protected UltimateRecyclerviewViewHolder newViewHolder(final View view) {
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(view.getContext(), "Click", Toast.LENGTH_SHORT).show();
}
});
final DVHolder dvHolder = new DVHolder(view, true);
dvHolder.swipeLayout.setOnDoubleClickListener(new SwipeLayout.DoubleClickListener() {
@Override
public void onDoubleClick(SwipeLayout layout, boolean surface) {
Toast.makeText(view.getContext(), "DoubleClick", Toast.LENGTH_SHORT).show();
}
});
dvHolder.deleteButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
removeAt(dvHolder.getPosition());
Toast.makeText(view.getContext(), "Deleted " + dvHolder.getPosition(), Toast.LENGTH_SHORT).show();
}
});
dvHolder.linearLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(view.getContext(), ""+dvHolder.getAdapterPosition(), Toast.LENGTH_SHORT).show();
}
});
return dvHolder;
}
@Override //Liste mit Daten füllen
protected void withBindHolder(UltimateRecyclerviewViewHolder holder, User user, int position) {
super.withBindHolder(holder, user, position);
((DVHolder) holder).name.setText(user.name);
((DVHolder) holder).lastMessage.setText(user.lastMessage);
//Das ParseFile (Image) wird nachher in der UserListActivity per Code geholt und zum ImageView hinzugefügt
}
//das so lassen
@Override
public DVHolder newFooterHolder(View view) {
return new DVHolder(view, false);
}
//das so lassen
@Override
public DVHolder newHeaderHolder(View view) {
return new DVHolder(view, false);
}
//Views etc. anlegen und zuweisen
public static class DVHolder extends UltimateRecyclerviewViewHolder {
public static final int layout = R.layout.user_item;
public TextView name;
public TextView lastMessage;
public ImageView userImage;
public Button deleteButton;
public LinearLayout linearLayout;
public SwipeLayout swipeLayout;
public DVHolder(View itemView, boolean bind) {
super(itemView);
if (bind) {
name = (TextView) itemView.findViewById(R.id.nameTV);
lastMessage = (TextView) itemView.findViewById(R.id.lastMessageTV);
userImage = (ImageView) itemView.findViewById(R.id.userImageIV);
deleteButton = (Button) itemView.findViewById(R.id.delete);
linearLayout = (LinearLayout) itemView.findViewById(R.id.linearLayout);
//diese standardmäßig so lassen, wenn Du swipe willst...
swipeLayout = (SwipeLayout) itemView.findViewById(R.id.recyclerview_swipe);
swipeLayout.setDragEdge(SwipeLayout.DragEdge.Right);
swipeLayout.setShowMode(SwipeLayout.ShowMode.PullOut);
}
}
}
}
编辑:(以下添加的XML文件）
content_user_list.xml
public class UserListActivity extends AppCompatActivity {
private UserListAdapter adapter;
private List<User> userList;
private ScrollSmoothLineaerLayoutManager mLayoutManager;
protected UltimateRecyclerView ultimateRecyclerView;
ParseObject image;
final private int REQUEST_CODE_ASK_PERMISSION = 123; //kann jegliche Zahl sein. Wir benutzens halt später
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
// fab.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View view) {
// Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
// .setAction("Action", null).show();
// }
// });
image = null;
ultimateRecyclerView = (UltimateRecyclerView) findViewById(R.id.userList_ultimate_recycler_view);
userList = new ArrayList<User>();
adapter = new UserListAdapter(userList);
adapter.setMode(SwipeItemManagerInterface.Mode.Single);
mLayoutManager = new ScrollSmoothLineaerLayoutManager(this, LinearLayoutManager.VERTICAL, false, 500);
ultimateRecyclerView.setLayoutManager(mLayoutManager);
ultimateRecyclerView.setAdapter(adapter);
// NICHT VERGESSEN DAS MANIFEST DIE PERMISSIONS EINZUTRAGEN !!! <----------------------------------
// wenn die Permission NICHT gegeben wurde... und was wir dann machen kommt in diesem Block
if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
if(ActivityCompat.shouldShowRequestPermissionRationale(this, android.Manifest.permission.READ_EXTERNAL_STORAGE)){
//Hier können wir eintragen, wieso wir eigentlich die Permission brauchen/verlangen
}else{
//Permission anfragen
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, REQUEST_CODE_ASK_PERMISSION);
}
}
//---------------------------------------------------------------------------------------------
ParseQuery<ParseUser> query = ParseUser.getQuery();
//Für Join <<<<---------
// query.whereMatchesKeyInQuery("Name der ID-Spalte hier", "Name der_FOREIGN_KEY-Spalte in der anderen Tabelle", query (der anderen Tabelle hier einfügen); Wir brauchen also query´s von den Tabellen und dann Matchen wir die Keys in den querys. Das kann man mit belieblig vielen Queries machen (also Joinen miteinander)!!!
if(ParseUser.getCurrentUser() != null){ //Wenn es einen User gibt, der eingeloggt ist.
query.whereNotEqualTo("username", ParseUser.getCurrentUser().getUsername()); //Query mit allen Nutzern OHNE mich selber. "username" ist hier die Spalte mit den Nutzer-Namen.
query.addAscendingOrder("username"); //Aufsteigend sortiert nach usernamen;
query.findInBackground(new FindCallback<ParseUser>() {
@Override
public void done(List<ParseUser> objects, ParseException e) {
if(e == null){
Log.i("andere User in DB", objects.size()+"");
Log.i("Liste vor befüllen", userList.size()+"");
if(objects.size() > 0){ // Wenn ich Objekte (Usernamen) habe in meiner Tabelle
/* for (int i = 0; i < objects.size(); i++) {
usernames.add(objects.get(i).getUsername());
}*/
// Alternative mit for-each-Schleife (ACHTUNG: Kann sein, dass du noch danach noch arrayadapter.notiyDataSetChanged() aufrufen musst! Teste es einfach mal ohne, ansonsten nach dem befüllen arrayadapter.notiyDataSetChanged(); aufrufen
/*for(ParseUser user: objects){
userList.add(new User(user.getUsername(), "lastMessage", image)); //TODO: Parsefile später als Image holen
}*/
for (int i = 0; i < objects.size(); i++) {
userList.add(new User(objects.get(i).getUsername(), "lastMessage", image)); //TODO: Parsefile später als Image holen
adapter.notifyItemInserted(i);
}
}
Log.i("Liste NACH befüllen", userList.size()+"");
}
}
});
}
//adapter.notifyDataSetChanged();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_user_list, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if(id == R.id.logout){
ParseUser.logOut();
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
}
return super.onOptionsItemSelected(item);
}
}
activity_user_list.xml
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/content_user_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="ibas.parse.mychat.UserListActivity"
tools:showIn="@layout/activity_user_list">
<com.marshalchen.ultimaterecyclerview.UltimateRecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="@+id/userList_ultimate_recycler_view"
app:recyclerviewEmptyView="@layout/empty_view"/>
</RelativeLayout>
user_item.xml
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_user_list" />
</android.support.design.widget.CoordinatorLayout>
非常感谢！
答案 0 :(得分：0)
添加
import tud.swt16w2.entity.TestEntity并使用 adapter.notifyDataSetChanged（）