[英]What is the best practice for debug statements which have string operations in them?
[英]what is the best practice way to save fragment state when you have to replace many of them?
我有一個主要活動,其中有許多片段相互替換,並且狀態總是丟失我什至嘗試了public void onSaveInstanceState(@NonNull Bundle outState)
但它仍然不起作用我什至在MainActivity
做了它以保留實例但現在仍然沒有我有一個CartOrderFragment
,當單擊按鈕時,我從FoodListFragment
向其中添加項目,但是每次我轉到CartOrderFragment
並返回FoodListFragment
並嘗試通過單擊之前的同一個按鈕添加更多項目CartOrderFragment
失去它的清單。
主活動.java
public class MainActivity extends AppCompatActivity implements
SetupAccountFragment.SetupAccountListener, FoodListFragment.ListenerFoodListFragment,
SignInAccountFragment.SignInAccountListener, SignUpAccountFragment.SignUpAccountListener {
FragmentManager fm;
FoodListFragment foodListFragment;
ArrayList<Food> foodsOrdered;
CartOrdersFragment cartOrdersFragment;
Map<Integer, Integer> cartValues = new HashMap<>();
@Override
public void sendOrders(ArrayList<Food> foods) {
foodsOrdered = foods;
}
@Override
protected void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
getSupportFragmentManager().putFragment(outState, "myFragment", cartOrdersFragment);
}
// this get called when the button gets clicked in the FoodListFragment
@Override
public void cartClickListener() {
cartOrdersFragment = CartOrdersFragment.newInstance(foodsOrdered);
fm.beginTransaction()
.replace(R.id.main_container, cartOrdersFragment)
.addToBackStack(null)
.commit();
}
// for sign up fragment
@Override
public void registerNowBtnListener() {
foodListFragment = new FoodListFragment();
fm.beginTransaction()
.replace(R.id.main_container, foodListFragment)
.commit();
}
// for sign up fragment
// for sign in fragment
@Override
public void signInBtn() {
foodListFragment = new FoodListFragment();
fm.beginTransaction()
.replace(R.id.main_container, foodListFragment)
.commit();
}
// for sign in fragment
@Override
public void sendToCart(int value, int adapterPosition) {
cartValues.put(adapterPosition, value);
foodListFragment.updateCartValue(getTotalValue());
}
private int getTotalValue() {
int value = 0;
for (Integer key : cartValues.keySet()) {
value += cartValues.get(key);
}
return value;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState != null) {
cartOrdersFragment = (CartOrdersFragment) getSupportFragmentManager().getFragment(savedInstanceState,
"myFragment");
}
fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.main_container);
if (fragment == null) {
// adding fragment to main container
fm.beginTransaction()
.replace(R.id.main_container, onBoardingFragment)
.replace(R.id.id_container_menu, new FoodCategoryFragment())
.addToBackStack(null)
.commit();
}
}
}
購物車訂單片段.java
public class CartOrdersFragment extends Fragment {
private CartOrdersAdapter cartOrdersAdapter;
private ArrayList<Food> foods;
private static final String KEY_ARRAYLIST = "ArrayList";
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList(KEY_ARRAYLIST, foods);
}
public static CartOrdersFragment newInstance(ArrayList<Food> foods) {
CartOrdersFragment cartOrdersFragment = new CartOrdersFragment();
Bundle args = new Bundle();
args.putParcelableArrayList(KEY_ARRAYLIST, foods);
cartOrdersFragment.setArguments(args);
return cartOrdersFragment;
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (savedInstanceState != null) {
foods = savedInstanceState.getParcelableArrayList(KEY_ARRAYLIST);
}
if (getArguments() != null) {
foods = getArguments().getParcelableArrayList(KEY_ARRAYLIST);
}
cartOrdersAdapter = new CartOrdersAdapter(getActivity(), foods);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setAdapter(cartOrdersAdapter);
}
public class FoodListFragment extends Fragment {
private FoodListAdapter foodListAdapter;
private BadgeHolderLayout badgeHolderLayout;
private ArrayList<Food> foods;
public interface ListenerFoodListFragment {
void sendToCart(int value, int adapterPosition);
void cartClickListener();
void sendOrders(ArrayList<Food> foods);
}
private ListenerFoodListFragment listenerFoodListFragment;
@Override
public void onAttach(@NonNull Context context) {
super.onAttach(context);
try {
listenerFoodListFragment = (ListenerFoodListFragment) context;
} catch (ClassCastException e) {
Log.d("FoodListFragment", "onAttach: " + e.getMessage());
}
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
foods = new ArrayList<>();
foods.add(new Food("Chicken", "99999$", R.drawable.chicken));
foods.add(new Food("Burger", "1000$", R.drawable.burger));
badgeHolderLayout.setOnClickListener(v -> listenerFoodListFragment.cartClickListener());
foodListAdapter = new FoodListAdapter(getActivity(), foods, listenerFoodListFragment);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setAdapter(foodListAdapter);
}
public void updateCartValue(int value) {
badgeHolderLayout.setCountWithAnimation(value);
}
}
FoodListAdapter.java
public class FoodListAdapter extends RecyclerView.Adapter<FoodListAdapter.ViewHolder>
implements Filterable {
private Context context;
private List<Food> foodList;
private List<Food> foodListFiltered;
private ArrayList<Food> orderedFood = new ArrayList<>();
FoodListFragment.ListenerFoodListFragment listenerFoodListFragment;
public FoodListAdapter(Context context, List<Food> foodList,
FoodListFragment.ListenerFoodListFragment listenerFoodListFragment) {
this.context = context;
this.foodList = foodList;
this.listenerFoodListFragment = listenerFoodListFragment;
this.foodListFiltered = foodList;
}
}
public class ViewHolder extends RecyclerView.ViewHolder {
public ViewHolder(@NonNull View itemView) {
super(itemView);
// this is the button that i mentioned
tvOk.setOnClickListener(v -> {
Food food = foodList.get(getAdapterPosition());
orderedFood.add(food);
listenerFoodListFragment.sendOrders(orderedFood);
});
fc.setOnClickListener(v -> fc.toggle(false));
}
}
}
你可以使用隱藏和顯示,試試這個
protected void onCreate(Bundle savedInstanceState){
fm.beginTransaction()
.add(R.id.main_container, fragmentOne)
.add(R.id.main_container, fragmentTwo)
.hide(fragmentTwo)
.addToBackStack(null)
.commit();
}
private void onBtnTwoClick() {
fm.beginTransaction().show(fragmentTwo).hide(fragmentOne)
.addToBackStack(null).commit();
}
private void onBtnOneClick() {
fm.beginTransaction().show(fragmentOne).hide(fragmentTwo)
.addToBackStack(null).commit();
}
這是替換的方法
你需要一個 StateHelper
public class FragmentStateHelper {
private HashMap<String, Fragment.SavedState> fragmentStates;
private FragmentManager fragmentManager;
public FragmentStateHelper(FragmentManager fragmentManager) {
fragmentStates = new HashMap<>();
this.fragmentManager = fragmentManager;
}
public void restoreState(Fragment fragment, String key) {
Fragment.SavedState savedState = fragmentStates.get(key);
if (savedState != null) {
if (!fragment.isAdded()) {
fragment.setInitialSavedState(savedState);
}
}
}
public void saveState(Fragment fragment, String key) {
if (fragment.isAdded()) {
fragmentStates.put(key, fragmentManager.saveFragmentInstanceState(fragment));
}
}
}
在替換之前保存舊片段並恢復新片段。
@Override
public void signInBtn() {
//save state here
foodListFragment = new FoodListFragment();
//restore foodListFragment here
fm.beginTransaction()
.replace(R.id.main_container, foodListFragment)
.commit();
}
你需要在片段中保存和恢復
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(KEY, str);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
if (savedInstanceState != null) {
str = savedInstanceState.getString(KEY);
}
}
你可以在這里查看: https : //medium.com/@bherbst/saving-fragment-state-yourself-522c3bca78c7
希望對你有所幫助,新年快樂。
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