[英]how can i refresh fragment when back button is pressed?
當按下后退按鈕時,如何刷新片段的視圖?
我已經在片段的onResume方法中嘗試過此方法,但是它不起作用。
好,這是代碼
@SuppressWarnings("unused")
public class RestaurantMenuFragment extends Fragment {
private static final String TAG = "MenuItemsFragment";
private static final String CATEGORIES_KEY = "categories";
private static final String SELECTED_CATEGORY_ID_KEY = "category";
private static final String RESTAURANT_KEY = "restaurant123";
private static final String RESTAURANT_KCITY = "city";
private Spinner mCategoriesSpinner;
private ArrayAdapter<CategoriesResponse.Category> mCategoriesAdapter;
private ListView mListView;
private List<MenuItem> mItems;
private MenuItemsAdapter mItemsAdapter;
private EmptyLayout mEmptyLayout;
private Restaurant mRestaurant;
private int mCategoryId;
private List<CategoriesResponse.Category> mCategories;
private RestaurantActivity mActivity;
private MainApplication mApplication;
private CategoriesResponse mCategoriesResponse;
private ActionBar mActionBar;
private Gson mGson;
int categ;
private ObjectGetter mObjectGetter;
public static RestaurantMenuFragment newInstance(Restaurant restaurant) {
RestaurantMenuFragment fragment = new RestaurantMenuFragment();
Bundle args = new Bundle();
args.putString(RESTAURANT_KEY, new Gson().toJson(restaurant));
String dd=restaurant.city;
Log.i("dd12", dd);
fragment.setArguments(args);
return fragment;
}
public RestaurantMenuFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mActivity = (RestaurantActivity) getActivity();
mApplication = (MainApplication) mActivity.getApplication();
mActionBar = mActivity.getSupportActionBar();
mGson = new Gson();
mObjectGetter = new ObjectGetter();
mCategories = new ArrayList<CategoriesResponse.Category>();
Log.i("mCategories",""+mCategories);
mItems = new ArrayList<MenuItem>();
Log.i("12345",""+mItems);
mItemsAdapter = new MenuItemsAdapter(getActivity(), mItems);
Bundle args = getArguments();
if (args != null) {
mRestaurant = mGson.fromJson(args.getString(RESTAURANT_KEY),
Restaurant.class);
}
if (savedInstanceState != null) {
mRestaurant = mGson.fromJson(
savedInstanceState.getString(RESTAURANT_KEY),
Restaurant.class);
mCategoryId = savedInstanceState.getInt(SELECTED_CATEGORY_ID_KEY);
mCategoriesResponse = mGson.fromJson(
savedInstanceState.getString(CATEGORIES_KEY),
CategoriesResponse.class);
}
assert mRestaurant != null;
updateCart();
}
public void updateCart() {
View view = mActionBar.getCustomView();
Button cartButton = (Button) view.findViewById(R.id.cartButton);
int nOfItems = 0;
if (mApplication.isCartCreated()) {
nOfItems = mApplication.getCart().getNOfAllItems();
}
cartButton.setText(String.format("%d", nOfItems));
if (nOfItems > 0) {
cartButton.setEnabled(true);
} else {
cartButton.setEnabled(false);
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
Gson gson = new Gson();
outState.putString(RESTAURANT_KEY, gson.toJson(mRestaurant));
outState.putInt(SELECTED_CATEGORY_ID_KEY, mCategoryId);
outState.putString(CATEGORIES_KEY, gson.toJson(mCategoriesResponse));
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onViewCreated(view, savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.spinner_list, container, false);
RestaurantActivity activity = (RestaurantActivity) getActivity();
String myDataFromActivity = activity.getMyData();
String myDataFromActivity1 = activity.getMyData1();
Log.i("myDataFromActivity",myDataFromActivity);
Log.i("myDataFromActivity1",myDataFromActivity1);
categ=Integer.parseInt(myDataFromActivity1);
mListView = (ListView) view.findViewById(R.id.list122334);
mListView.setAdapter(mItemsAdapter);
Log.d(TAG,"Querying items url "
+ Urls.menuItemsQuery(mRestaurant.id,categ));
mEmptyLayout = EmptyLayout.with(getActivity()).to(mListView)
.setEmptyMessage(R.string.categories_empty_message)
.showLoading();
loadItems();
return view;
}
private void loadItems() {
mEmptyLayout.showLoading();
mItems.clear();
mObjectGetter.getJsonObjectOrDialog(mActivity,
Urls.menuItemsQuery(mRestaurant.id, categ),
ItemsResponse.class,
new ObjectGetter.OnFinishedListener<ItemsResponse>() {
@Override
public void onFinishedLoadingObject(
ItemsResponse itemsResponse) {
mEmptyLayout.showEmpty();
if (itemsResponse != null
&& itemsResponse.items != null) {
mItems.addAll(itemsResponse.items);
}
mItemsAdapter.notifyDataSetChanged();
}
});
}
private class MenuItemsAdapter extends ArrayAdapter<MenuItem> {
private static final String TAG = "MenuItemsAdapter";
public MenuItemsAdapter(Context context, List<MenuItem> menuItems) {
super(context, 0, menuItems);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
final MenuItem menuItem = getItem(position);
View view = convertView;
final ViewHolder viewHolder;
LayoutInflater inflater;
if (convertView == null) {
inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.menu_item, parent, false);
viewHolder = new ViewHolder();
viewHolder.name = (TextView) view.findViewById(R.id.name);
viewHolder.description = (TextView) view.findViewById(R.id.description);
viewHolder.price = (TextView) view.findViewById(R.id.price);
viewHolder.add = (Button) view.findViewById(R.id.add);
viewHolder.selectedView = view.findViewById(R.id.selectedView);
viewHolder.remove = (Button) view.findViewById(R.id.remove);
viewHolder.total = (TextView) view.findViewById(R.id.itemTotal);
viewHolder.quantity = (TextView) view.findViewById(R.id.quantity);
view.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
try
{
viewHolder.name.setText(menuItem.name);
viewHolder.description.setText(menuItem.description);
viewHolder.price.setText(String.valueOf(menuItem.price));
}catch(NullPointerException e){
e.printStackTrace();
}
viewHolder.add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mApplication.createNewCartIfPossibleAndAskIfNot(
getActivity(), mRestaurant,
new MainApplication.OnCreateCartListener() {
@Override
public void onCreateCart(Cart cart) {
cart.addOne(menuItem);
updateItemFromCart(menuItem, viewHolder);
updateCart();
}
});
}
});
viewHolder.remove.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!mApplication.isCartCreated()) {
return;
}
mApplication.getCart().removeOne(menuItem);
updateItemFromCart(menuItem, viewHolder);
updateCart();
}
});
return view;
}
private void updateItemFromCart(MenuItem menuItem, ViewHolder viewHolder) {
if (!mApplication.isCartCreated()) {
return;
}
int quantity = mApplication.getCart().getNOfItemsOfType(menuItem);
if (quantity > 0) {
viewHolder.selectedView.setVisibility(View.VISIBLE);
} else {
viewHolder.selectedView.setVisibility(View.GONE);
}
viewHolder.quantity.setText(String.valueOf(quantity));
viewHolder.total.setText(String.valueOf(quantity
* menuItem.price));
}
class ViewHolder {
TextView name;
TextView description;
TextView price;
Button add;
View selectedView;
Button remove;
TextView total;
TextView quantity;
}
}
@Override
public void onResume() {
super.onResume();
updateCart();
mItems.clear();
if (mItemsAdapter != null) {
mItemsAdapter.notifyDataSetChanged();
}
}
@Override
public void onDestroy() {
if (mObjectGetter != null) {
mObjectGetter.stopRequests();
}
super.onDestroy();
}
}
現在,我想在用戶按下后退按鈕時更新listvieww數據。 我在片段的onResume()方法中設置了新的loadItems()方法。 調用此方法,但出現舊的列表視圖數據,也出現新的數據...
后退按鈕應從活動中處理。 您可以覆蓋Activity中的onBackPressed,並在相應的片段上調用一個函數來reloadItems()。
這是我能想到的3種選擇。
獲取對Fragment的引用,並調用reLoadItems函數,並更好地為該片段實現的通信定義接口。
比第一個更好的解決方案。 添加一個LocalBroadcast,由Activity廣播,您的片段在接收廣播時監聽和更新數據。
例如: http : //luboganev.github.io/blog/messaging-with-localbroadcastmanager/
例如: http : //www.vogella.com/tutorials/JavaLibrary-EventBusOtto/article.html
如ramesh所述,后退按鈕處理發生在保存片段的活動類中。 這是一個簡單的示例,說明如何處理片段的這些后退按鈕事件。
活動代碼:
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
boolean returnSuperKeyDown = true;
if(keyCode == KeyEvent.KEYCODE_BACK){
Fragment fragment = getYourCurrentFragment();
if (fragment instanceof YourFragment) {
returnSuperKeyDown = ((YourFragment) fragment).onFragmentKeyDown();
}
}
if (returnSuperKeyDown) {
return super.onKeyDown(keyCode, event);
} else {
return true;
}
}
YourFragment方法:
public boolean onFragmentKeyDown() {
updateYourFragment();
return false;
}
@Rithe,@sunder夏爾馬
根據我的看法,從其他片段回來時,刷新片段很簡單,
我們只需要重寫onActivityCreated方法即可獲得刷新片段。
像
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
//your code which you want to refresh
loadItems();
}
您也可以使用onStart()方法更新/刷新片段。
public void onStart(){
super.onStart();
//update your fragment
}
這對我來說很好。
調用您的loadItem()方法onHiddenChanged(布爾隱藏)方法.onHiddenChanged被重寫的方法
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