【发布时间】：2018-03-25 16:35:31
【问题描述】：
网上有很多关于这个的教程。但是，我尝试了很多，但没有一个能正确地完成我的预期。
我对 Android 和应用程序开发非常陌生，但有一些开发网站和 API 的经验。我开发了一个网站，并想创建一个简单的 Android 应用程序来为用户显示事件源。
因此，经过一些研究，有效处理来自 API 的大量 JSON 数据列表的最佳方法似乎是使用 RecyclerView，而 CardViews 会稍微提升设计。
所以我设置了一个带有底部导航栏的项目，并创建了三个选项卡（事件、配置文件和通知）。这些选项卡返回一个片段，列表应该在事件片段内。我已对其进行硬编码以显示 5 个项目，但它从不显示卡片。所以我不确定它错在哪里。其他片段正确显示
这是我的代码：
基本片段
public abstract class BaseFragment extends AppCompatActivity {
protected abstract Fragment createFragment();
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user);
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.content);
if(fragment == null){
fragment = createFragment();
fm.beginTransaction()
.add(R.id.events_fragment_container, fragment)
.commit();
}
}
}
事件片段、适配器和 ViewHolder
public class EventsRecyclerFragment extends Fragment{
public static Fragment newInstance(){
return new EventsRecyclerFragment();
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.events_recycler_view_fragment, container, false);
RecyclerView recyclerView = view.findViewById(R.id.events_recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setAdapter(new EventsRecyclerViewAdapter());
return view;
}
private class EventsRecyclerViewHolder extends RecyclerView.ViewHolder{
private CardView mCardView;
private TextView mTextView;
public EventsRecyclerViewHolder(View itemView) {
super(itemView);
}
public EventsRecyclerViewHolder(LayoutInflater inflater, ViewGroup container){
super(inflater.inflate(R.layout.events_card_view, container, false));
mCardView = itemView.findViewById(R.id.events_card_container);
}
}
private class EventsRecyclerViewAdapter extends RecyclerView.Adapter<EventsRecyclerViewHolder>{
@Override
public EventsRecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(getContext());
return new EventsRecyclerViewHolder(inflater, parent);
}
@Override
public void onBindViewHolder(EventsRecyclerViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return 5;
}
}
}
我在 Activity 上的使用情况
public class UserActivity extends AppCompatActivity {
public static final String PREFS_NAME = "Preferences";
private static final String PREF_EMAIL = "EMAIL";
private static final String PREF_PASSWORD = "PASSWORD";
private static final String PREF_TOKEN = "TOKEN";
Button btnLogout;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
switch (item.getItemId()) {
case R.id.navigation_events:
transaction.replace(R.id.content, new EventsRecyclerFragment().newInstance()).commit();
return true;
case R.id.navigation_profile:
transaction.replace(R.id.content, new UserFragment()).commit();
return true;
case R.id.navigation_notifications:
transaction.replace(R.id.content, new NotificationsFragment()).commit();
return true;
}
return false;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user);
btnLogout = (Button) findViewById(R.id.btnLogin);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}
}
谁能帮助我如何让这个基本列表显示出来？ 提前致谢
【问题讨论】：
-
从 Fragment 发布您的 xml
标签： android android-layout android-fragments android-recyclerview android-cardview