我正在开发一个项目，我必须从json中动态添加标签和数据。
以下是我添加标签
的活动中的代码private void getShopDetails() {
coordinatorLayout.setVisibility(View.GONE);
new ProgressDialog(this);
ProgressDialog.show();
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(shopDetailsJsonUrl, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
SharedPreferences sharedPreferences = getSharedPreferences("ShopDetailsJson", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("sdresponse", response.toString());
editor.apply();
ProgressDialog.dismiss();
coordinatorLayout.setVisibility(View.VISIBLE);
try {
JSONArray shopDetailsArray = response.getJSONArray("shop_details");
JSONObject shopDetailsObj = shopDetailsArray.getJSONObject(0);
shopName = shopDetailsObj.getString("shop_name");
phone = shopDetailsObj.getString("tel");
shopNum = shopDetailsObj.getString("shop_no");
shopAddress = shopDetailsObj.getString("shop_address");
shopImage = shopDetailsObj.getString("featured_image");
Glide.with(getApplicationContext()).load("http://allmartapp.com/appapi/uploads/" + shopImage).diskCacheStrategy(DiskCacheStrategy.SOURCE).into(backdrop);
colLayout.setTitle(shopName);
address.setText("Address - " + shopAddress);
JSONArray tabsArray = response.getJSONArray("category");
if (tabsArray != null) {
categoryId = new int[tabsArray.length()];
for (int i = 0; i < tabsArray.length(); i++) {
JSONObject tabsObj = tabsArray.getJSONObject(i);
tabLayout.addTab(tabLayout.newTab().setText(tabsObj.getString("category_name")));
categoryId[i] = tabsObj.getInt("category_id");
}
tabLayout.setTabGravity(TabLayout.GRAVITY_CENTER);
PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
pager.setAdapter(pagerAdapter);
pager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
pager.setOffscreenPageLimit(tabLayout.getTabCount());
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
pager.setCurrentItem(tab.getPosition());
ShopDetailsTabsFragment.sgetid(categoryId[tab.getPosition()]);
Log.d("CATIID", categoryId[tab.getPosition()] + "");
pager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
ProgressDialog.dismissWithError();
}
});
int socketTimeout = 30000;//30 seconds - change to what you want
RetryPolicy policy = new DefaultRetryPolicy(socketTimeout, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
jsonObjectRequest.setRetryPolicy(policy);
AppController.getInstance().addToRequestQueue(jsonObjectRequest);
}
以下是片段
的代码public class ShopDetailsTabsFragment extends Fragment {
RecyclerView recyclerView;
boolean isViewShown = true;
CategoryListItemsAdapter shopListRvAdapters;
private String shopDetailsJsonUrl = "http://allmartapp.com/appapi/json/get_shop_details_by_shop_id/";
private String baseshopDetailsJsonUrl = "http://allmartapp.com/appapi/json/get_shop_details_by_shop_id/";
ArrayList<CategoryItemsListModel> arrayList = new ArrayList<>();
static int catid = 0;
int shopId;
Boolean isdataloaded = false;
ProgressBar progressBar;
private boolean fragmentResume = false;
private boolean fragmentVisible = true;
private boolean fragmentOnCreated = false;
public ShopDetailsTabsFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_shop_details_tabs, container, false);
recyclerView = (RecyclerView) v.findViewById(R.id.rv);
recyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 2));
progressBar = (ProgressBar) v.findViewById(R.id.progressBarTabs);
SharedPreferences sharedPreferences = getActivity().getSharedPreferences("SHOPID", Context.MODE_PRIVATE);
shopId = sharedPreferences.getInt("shopid", 0);
if (!fragmentResume && fragmentVisible) { //only when first time fragment is created
makeJsonRequest();
}
shopListRvAdapters = new CategoryListItemsAdapter(arrayList, getActivity());
recyclerView.setAdapter(shopListRvAdapters);
return v;
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser && isResumed()) { // only at fragment screen is resumed
fragmentResume = true;
fragmentVisible = false;
fragmentOnCreated = true;
makeJsonRequest();
} else if (isVisibleToUser) { // only at fragment onCreated
fragmentResume = false;
fragmentVisible = true;
fragmentOnCreated = true;
} else if (!isVisibleToUser && fragmentOnCreated) {// only when you go out of fragment screen
fragmentVisible = false;
fragmentResume = false;
}
// if (getView() != null) {
// isViewShown = true;
// makeJsonRequest();
//
//
// // fetchdata() contains logic to show data when page is selected mostly asynctask to fill the data
// } else {
// isViewShown = false;
// }
}
public static void sgetid(int cat) {
catid = cat;
}
private void getShopCat() {
recyclerView.setAdapter(null);
shopDetailsJsonUrl += shopId;
arrayList.clear();
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(shopDetailsJsonUrl, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
isdataloaded = true;
Log.d("JSON", response.toString());
try {
JSONArray categoryArray = response.getJSONArray("category");
if (arrayList != null) {
if (arrayList.size() > 0)
arrayList.clear();
}
for (int i = 0; i < categoryArray.length(); i++) {
JSONObject catObj = categoryArray.getJSONObject(i);
int category_id = catObj.getInt("category_id");
if (category_id == catid) {
JSONArray productArray = catObj.getJSONArray("product");
for (int j = 0; j < productArray.length(); j++) {
JSONObject productObj = productArray.getJSONObject(j);
String name = productObj.getString("product_name");
String image = "http://allmartapp.com/appapi/uploads/" + productObj.getString("image_name");
int id = productObj.getInt("product_id");
int price = productObj.getInt("price");
arrayList.add(new CategoryItemsListModel(id, image, name, price));
}
shopListRvAdapters = new CategoryListItemsAdapter(arrayList, getActivity());
recyclerView.setAdapter(shopListRvAdapters);
shopListRvAdapters.notifyDataSetChanged();
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
int socketTimeout = 30000;//30 seconds - change to what you want
RetryPolicy policy = new DefaultRetryPolicy(socketTimeout, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
jsonObjectRequest.setRetryPolicy(policy);
AppController.getInstance().addToRequestQueue(jsonObjectRequest);
shopDetailsJsonUrl = baseshopDetailsJsonUrl;
}
void makeJsonRequest() {
SharedPreferences sharedPreferences = getActivity().getSharedPreferences("ShopDetailsJson", Context.MODE_PRIVATE);
String response = sharedPreferences.getString("sdresponse", null);
try {
JSONArray jsonArray = new JSONObject(response).getJSONArray("category");
Log.d("TBASARRAY", jsonArray + "");
progressBar.setVisibility(View.GONE);
if (arrayList != null) {
if (arrayList.size() > 0)
arrayList.clear();
}
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject catObj = jsonArray.getJSONObject(i);
int category_id = catObj.getInt("category_id");
if (category_id == catid) {
JSONArray productArray = catObj.getJSONArray("product");
for (int j = 0; j < productArray.length(); j++) {
JSONObject productObj = productArray.getJSONObject(j);
String name = productObj.getString("product_name");
String image = "http://allmartapp.com/appapi/uploads/" + productObj.getString("image_name");
int id = productObj.getInt("product_id");
int price = productObj.getInt("price");
arrayList.add(new CategoryItemsListModel(id, image, name, price));
}
shopListRvAdapters = new CategoryListItemsAdapter(arrayList, getActivity());
recyclerView.setAdapter(shopListRvAdapters);
shopListRvAdapters.notifyDataSetChanged();
}
}
} catch (JSONException e) {
e.printStackTrace();
}
recyclerView.addOnItemTouchListener(new CategoryListActivity.RecyclerTouchListener(getActivity(), recyclerView, new CategoryListActivity.OnClickListener() {
@Override
public void onClick(View v, int position) {
int id = arrayList.get(position).getId();
SharedPreferences sharedPreferences = getActivity().getSharedPreferences("CATITEMID", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt("catitemid", id);
editor.apply();
startActivity(new Intent(getActivity(), ItemDetailView.class));
}
@Override
public void onLongClick(View v, int position) {
}
}));
// shopDetailsJsonUrl = baseshopDetailsJsonUrl;
}
我的问题是只在我滑动选项卡时调用函数makeJsonRequest（）。实际上，除非我滑动标签，否则不会调用onCreateview方法。
此外，当我按下并返回该活动时，按下时留下的该选项卡的数据将显示在第一个选项卡中。
任何帮助/指导都将不胜感激。
答案 0 :(得分：0)
我建议您查看ViewPager's setOffscreenPageLimit(int)方法。
它控制在显示之前必须预先初始化/删除多少个选项卡。
至于“后退”问题。可能第一个片段被“添加”到活动Backstack，而其他片段被“替换”。因此，调用onBackPressed的{{1}}只会回到Backstack中。