Android适配器父级宽度=0
Android适配器父级宽度=0
提问于 2017-05-05 08:31:09
也许我累了，但我错过了代码中发生的事情。我有一个碎片的活动。
我的活动HomeActivity调用一个webservice来填充一个列表(我的业务对象)，它执行这个onResume()。
我的片段WalletFragment有一个mehtod refreshCardListView()，它使用适配器来显示列表。它执行这个onResume()。
我所做的直到现在都在起作用：
- HomeActivity.onCreate()显示WalletFragment，WalletFragment.onResume()调用this.refreshCardList()，但此时cardList为空，因此适配器不显示任何内容
- HomeActivity.onResume()调用webservice，在成功调用walletFragment.refreshCardList()时，cardList被webservice填充，因此tid正确显示列表。
现在，我发现调用refreshList两次是愚蠢的，所以我尝试将displayWalletFragment从HomeActivity.onCreate()移到was服务的成功回调，并从HomeActivity中删除对refreshCardList的调用，只将其保留在WalletFragment.onResume()中，这样就会这样：
- HomeActivity.onResume()调用webservice，在成功显示WalletFragment时，WalletFragment.onResume()调用this.refreshCardList()，cardList已被webservice填充。
但是此时我的适配器崩溃了，因为parent.getWidth() == 0(而且我需要父级宽度来显示卡片图像)。
我不明白为什么，通过移动这段代码，父视图现在不会被初始化，您有什么想法吗？
这就是我使用的代码，我唯一改变的是从onCreate中删除onCreate(False)，并在refreshCardList的成功返回中将它移动，并从那里删除walletFragment.refreshCardListView()。
HomeActivity.java
public class HomeActivity extends Activity {
CardService cardService = new CardService(this);
UserService userService = new UserService(this);
User user = null;
Set<WegaCard> userCards = null;
ProfileFragment profileFragment;
WalletFragment walletFragment;
/*
* Saving card images for performance concerns.
*/
Map<String, Bitmap> cardsImageBitmaps = new HashMap<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
initializeComponents();
styleCompnents();
displayWalletFragment(false);
}
@Override
protected void onResume() {
Log.d(this, "fired HomeActivity.onResume()");
super.onResume();
user = null;
userCards = null;
refreshUser(
new SingleResultCallback<User>() {
@Override
public void onResponse(User cards) {
Log.d(this, "user: " + user.toString());
HomeActivity.this.user = user;
profileFragment.refreshUser();
}
},
new ErrorCallback() {
@Override
public void onResponse(Throwable error) {
Log.e(this, "error: " + error.toString());
}
});
refreshCardList(
new SingleResultCallback<Set<WegaCard>>() {
@Override
public void onResponse(Set<WegaCard> cards) {
Log.d(this, "cards: " + cards.toString());
userCards = cards;
walletFragment.refreshCardListView();
}
},
new ErrorCallback() {
@Override
public void onResponse(Throwable error) {
Log.e(this, "error: " + error.toString());
}
});
}
private void refreshCardList(SingleResultCallback<Set<WegaCard>> successCallback, ErrorCallback errorCallback) {
Log.d(this, "fired HomeActivity.refreshCardList()");
// First empty list...
userCards = new LinkedHashSet<>();
// ...then fill it back
cardService.getCards(false, true, successCallback, errorCallback);
}
private void refreshUser(SingleResultCallback<User> successCallback, ErrorCallback errorCallback) {
Log.d(this, "fired HomeActivity.refreshUser()");
// First empty user...
userCards = new LinkedHashSet<>();
// ...then recreate it
userService.getUser(successCallback, errorCallback);
}
public void displayWalletFragment(boolean addToBackStack) {
displayFragment(WalletFragment.newInstance(), addToBackStack);
}
public void displayCardFragment(String cardNumber, boolean addToBackStack) {
displayFragment(CardFragment.newInstance(cardNumber), addToBackStack);
}
public void displayProfileFragment(boolean addToBackStack) {
displayFragment(ProfileFragment.newInstance(), addToBackStack);
}
private void displayFragment(HomeFragment fragment, boolean addToBackStack) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.home_fragment, fragment);
if (addToBackStack) {
fragmentTransaction.addToBackStack(null);
}
fragmentTransaction.commit();
}
public void profileEdit(View view) {
ActivityLauncher.getInstance().startProfileActivityForResult(this, ProfileActivity.ProfileEditMode.EDIT_PROFILE, user);
}
public Map<String, Bitmap> getCardsImageBitmaps() {
return cardsImageBitmaps;
}
}WalletFragment.java
public class WalletFragment extends HomeFragment {
List<WegaCard> cardList;
ListView cardListView;
WegaCardAdapter adapter;
public static WalletFragment newInstance() {
WalletFragment fragment = new WalletFragment();
// Bundle args = new Bundle();
// fragment.setArguments(args);
return fragment;
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
activity.walletFragment = this;
cardListView = (ListView) getView().findViewById(R.id.fragment_home_wallet_list);
cardListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
activity.displayCardFragment(cardList.get(position).getCardNumber(), true);
}
});
}
@Override
public void onResume() {
Log.d(this, "fired WalletFragment.onResume()");
super.onResume();
refreshCardListView();
}
void refreshCardListView() {
Log.d(this, "fired WalletFragment.refreshCardListView()");
// First empty list...
cardList = new ArrayList<>();
cardList.addAll(activity.userCards);
adapter = new WegaCardAdapter(activity, R.layout.adapter_card_item, cardList);
cardListView.setAdapter(adapter);
getView().findViewById(R.id.fragment_home_wallet_empty).setVisibility(cardList.isEmpty() ? View.VISIBLE : View.GONE);
}
}WegaCardAdapter.java
public class WegaCardAdapter extends ArrayAdapter<WegaCard> {
public WegaCardAdapter(@NonNull Context context, @LayoutRes int resource, @NonNull List<WegaCard> objects) {
super(context, resource, objects);
}
/**
* Data that should appear in the view should be added here
*/
private class ViewHolder {
ImageView imageView;
}
/*
* Note: using layout_height="match_parent" on the ListView helps Android calculate faster
* the elements that are displayed on screen, and prevent the array adapter for calling
* getView() too many times, thus improving the display speed
*/
public View getView(int position, View convertView, ViewGroup parent) {
Log.d(this, "fired WegaCardAdapter.getView(" + position + ")");
ViewHolder holder = null;
WegaCard card = getItem(position);
LayoutInflater mInflater = (LayoutInflater) getContext().getSystemService(android.app.Activity.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = mInflater.inflate(R.layout.adapter_card_item, null);
holder = new ViewHolder();
holder.imageView = (ImageView) convertView.findViewById(R.id.adapter_card_image);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
Bitmap cardImage = null;
if (getContext() instanceof HomeActivity) {
Log.d(this, "In home activity \\o/");
Map<String, Bitmap> savedBitmaps = ((HomeActivity) getContext()).getCardsImageBitmaps();
if (savedBitmaps.containsKey(card.getCardNumber())) {
Log.d(this, "Found saved image, using it ^^");
cardImage = savedBitmaps.get(card.getCardNumber());
}
else {
Log.d(this, "Didn't found saved image éè building and saving it for later!");
cardImage = card.getRoundedScaledBitmap(getContext(), parent.getWidth());
savedBitmaps.put(card.getCardNumber(), cardImage);
}
}
else {
Log.d(this, "Not in home activity?");
cardImage = card.getRoundedScaledBitmap(getContext(), parent.getWidth());
}
holder.imageView.setImageBitmap(cardImage);
return convertView;
}
}activity_home.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:auto="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<!-- Fragment will be displayed here -->
<LinearLayout
android:id="@+id/home_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
</LinearLayout>
</ScrollView>
</RelativeLayout>fragment_home_wallet.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/fragment_home_wallet_root"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center">
<LinearLayout
android:id="@+id/fragment_home_wallet_empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
android:visibility="gone">
<ImageView
android:src="@drawable/icon_card_white"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<com.gaetanl.aspa.ui.component.StaticTextView
android:id="@+id/fragment_home_wallet_empty_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/defaultSpacing"
android:text="@string/dashboard_text_nocard" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/defaultSpacing"
android:gravity="center_vertical"
android:orientation="horizontal">
<com.gaetanl.aspa.ui.component.StaticTextView
android:id="@+id/fragment_home_wallet_empty_text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/dashboard_text_tap1" />
<ImageView
android:src="@drawable/icon_plus_white"
android:layout_width="@dimen/inlineIcon"
android:layout_height="@dimen/inlineIcon"
android:layout_marginLeft="@dimen/wordSpacing"
android:layout_marginRight="@dimen/wordSpacing" />
<com.gaetanl.aspa.ui.component.StaticTextView
android:id="@+id/fragment_home_wallet_empty_text2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/dashboard_text_tap2" />
</LinearLayout>
</LinearLayout>
<!-- Note: using layout_height="match_parent" on the ListView helps Android calculate faster
the elements that are displayed on screen, and prevent the array adapter for calling
getView() too many times, thus improving the display speed -->
<ListView
android:id="@+id/fragment_home_wallet_list"
android:layout_width="match_parent"
android:layout_height="match_parent">
</ListView>
</LinearLayout>
</LinearLayout>Stack Overflow用户
回答已采纳
发布于 2017-05-05 21:01:44
我在这里找到了解决方案：When should I get Width View in Fragment。
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
view.post(new Runnable() {
@Override
public void run() {
// do operations or methods involved
// View.getWidth(); or View.getHeight();
// here
}
});
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/43800148
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