我有一个主要活动,该活动在带有标签的View Pagers中显示3个片段。
mainActivity.java
public class mainActivity extends AppCompatActivity {
globalVariableActivity variable = new globalVariableActivity();
private APIService mAPIService;
private TextView mResponseTv;
private RecyclerView recyclerView;
private Token token = new Token("","","");
private Gson gson = new Gson();
private Context context=mainActivity.this;
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//check if token is still active
String current_token=token.getToken(context);
MyFirebaseInstanceIDService Fcm= new MyFirebaseInstanceIDService();
Fcm.onTokenRefresh(context,current_token);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new BeritaFragment(), "Berita");
adapter.addFragment(new DiskusiFragment(), "Diskusi");
adapter.addFragment(new PesanFragment(), "Pesan");
viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
//Toast.makeText(context,"Item " + position + " shown.", Toast.LENGTH_SHORT).show();
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
Toast.makeText(context,"Position : " + position + " Title : "+ mFragmentTitleList.get(position) + " shown.", Toast.LENGTH_SHORT).show();
return mFragmentTitleList.get(position);
}
}
interface LyfecycleListener {
void onCreatedView();
}
这是第一个片段代码
beritaFragment.java
public class BeritaFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private APIService mAPIService = APIUtils.getAPIService();;
private Gson gson = new Gson();
private TextView createdAtText;
private TextView judulText;
private ImageView imageView;
private RecyclerView mRecyclerView;
private ListAdapter mListadapter;
private ArrayList<DataBerita> list_berita= new ArrayList<>();
private OnFragmentInteractionListener mListener;
public BeritaFragment() {
}
// TODO: Rename and change types and number of parameters
public static BeritaFragment newInstance(String param1, String param2) {
BeritaFragment fragment = new BeritaFragment();
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getBeritaTask getBerita= new getBeritaTask();
try {
Log.d("berita :", "On create 1");
getBerita.execute().get(10000, TimeUnit.MILLISECONDS);
Log.d("berita :", "On create 2");
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_berita, container, false);
Log.d("Berita","On create view");
Toast.makeText(getActivity() ,"Berita Fragment onCreateView", Toast.LENGTH_SHORT).show();
ArrayList<DataBerita> data_berita;
mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
judulText = (TextView)view.findViewById(R.id.summary_judul);
createdAtText = (TextView)view.findViewById(R.id.created_at);
//imageView = (ImageView)view.findViewById(R.id.gambar);
final LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(layoutManager);
//data_berita=getBeritaList();
Log.d("Berita","1");
Log.d("Berita List : ", list_berita.toString());
Log.d("Berita","3");
mListadapter = new ListAdapter(list_berita);
mRecyclerView.setAdapter(mListadapter);
//Log.d("Berita view :", view.toString());
return view;
}
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ViewHolder>
{
private ArrayList<DataBerita> dataList;
public ListAdapter(ArrayList<DataBerita> data)
{
this.dataList = data;
}
public class ViewHolder extends RecyclerView.ViewHolder
{
TextView judulText;
TextView waktuText;
ImageView gambarView;
public ViewHolder(View itemView)
{
super(itemView);
this.judulText = (TextView) itemView.findViewById(R.id.summary_judul);
this.waktuText = (TextView) itemView.findViewById(R.id.created_at);
//this.gambarView = (ImageView) itemView.findViewById(R.id.gambar);
}
}
@Override
public ListAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.berita_list_layout, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(ListAdapter.ViewHolder holder, final int position)
{
Uri ImageURI=Uri.parse(dataList.get(position).getGambar_utama());
holder.judulText.setText(dataList.get(position).getSummary_judul());
holder.waktuText.setText(dataList.get(position).getCreated_at());
//holder.gambarView.setImageURI(ImageURI);
holder.itemView.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Toast.makeText(getActivity(), "Item " + position + " is clicked.", Toast.LENGTH_SHORT).show();
}
});
}
@Override
public int getItemCount()
{
return dataList.size();
}
}
private class getBeritaTask extends AsyncTask<Void, Void, Void> {
protected void onPreExecute() {
Log.d("Berita","2.1");
}
protected Void doInBackground(Void... voids) {
mAPIService.getBeritaList().enqueue(new Callback<Berita>() {
@Override
public void onResponse(Call<Berita> call, Response<Berita> response) {
list_berita = new ArrayList<>();
DataBerita data_berita = new DataBerita("","","","");
String id_berita;
String judul;
String gambar_utama;
String created_at;
Log.d("Berita","2.2");
if(response.isSuccessful()) {
Berita body = gson.fromJson(response.body().toString(),Berita.class);
for (int i = 0; i < body.getList_berita().getData().size(); i ++) {
id_berita=body.getList_berita().getData().get(i).getId_berita();
judul=body.getList_berita().getData().get(i).getSummary_judul();
gambar_utama=body.getList_berita().getData().get(i).getGambar_utama();
created_at=body.getList_berita().getData().get(i).getCreated_at();
data_berita = new DataBerita(id_berita,judul,gambar_utama,created_at);
list_berita.add(data_berita);
}
Log.d("Berita List",list_berita.toString());
}else{
Log.d("Berita", "Fail");
}
}
@Override
public void onFailure(Call<Berita> call, Throwable t) {
Log.d("Berita Fail", t.getMessage());
}
});
return null;
}
}
这是第2和第3个片段(这2个片段仍然大部分为空,只有烤面包的代码,现在才记录)
DiskusiFragment.java
public class DiskusiFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public DiskusiFragment() {
// Required empty public constructor
}
// TODO: Rename and change types and number of parameters
public static DiskusiFragment newInstance(String param1, String param2) {
DiskusiFragment fragment = new DiskusiFragment();
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Toast.makeText(getActivity() ,"Diskusi Fragment onCreateView", Toast.LENGTH_SHORT).show();
return inflater.inflate(R.layout.fragment_diskusi, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
问题出在这里
片段onCreateView函数似乎在/的错误片段中被调用。
当我启动应用程序时,发生了什么事:
接下来会发生什么,取决于我的工作:
当我从第一个片段=>第二个片段更改时,创建视图上的第三个片段被称为
当我从第一个片段=>第三个片段更改时,创建视图上的第三个片段称为
当我从第二个片段=>第一个片段切换时,创建视图上没有片段称为
当我从第二个片段=>第三个片段切换时,在创建视图上没有片段称为
当我从第3个片段=>第2个片段切换时,在创建视图上没有调用任何片段(或者有时在创建视图上调用了第一个片段)
当我从第三个片段=>更改为第一个片段时,创建视图上的第一个片段称为
这是假设的事情吗(关于onCreateView函数在错误的片段上被调用)?
如果没有,我在哪里写错了代码?
非常感谢您
* EDIT:此行为是正常现象,我真的是android新手。非常抱歉给您带来不便
答案 0 :(得分:0)
“错误”片段是什么意思? View分页器在导航到它之前先创建下一个片段,以使过渡平滑而快速。并且当创建片段时,将相应地调用其生命周期方法,此行为没有任何问题。如果要在用户在视图分页器中滑动到特定片段时执行某些操作,则可以使用OnPageChangeListener。
答案 1 :(得分:0)
除了显示的片段以外,FragmentPagerAdapter还将其他片段保持在恢复状态。
如果要初始化片段中的内容,应在以下情况下进行
OnCreate
被调用。
与UI相关的任何事情都应正确加载
onViewCreated
此外,如果您想获得有关如何在ViewPager中处理片段的更多信息
@Shreyas Shetty在this线程上很好回答