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我有一個應用程序項目，其中有10個片段。當用戶打開一個片段時，我想在代碼中知道這一點，並保存片段作爲最後一位Fragment用戶訪問過的片段。如何檢測片段當前正在使用
如果用戶關閉應用程序並再次打開，最後訪問的這個片段將顯示給用戶。
我讀了很多關於這個問題的答案，並沒有就解決方案達成共識，以瞭解Fragment目前對用戶可見的內容。
我在想FragmentManager的子類可能用來檢測彈出和監視隊列狀態。
或者可能會在Fragment中放入一些GestureDetector.OnGestureListener，當發生火災時，我可以保存上次訪問的Fragment用戶。
任何幫助將是爐排
，當用戶在該片段中按返回按鍵
/**
* user press back button
*/
@Override
public void onBackPressed() {
//Fragment fragment = getVisibleFragment();
//get the name from the topmost BackStackEntry which is also the fragment tag.
String fragmentTag = mFragManager.getBackStackEntryAt(mFragManager.getBackStackEntryCount()-1).getName();
Fragment currentFrag = mFragManager.findFragmentByTag(fragmentTag);
if (currentFrag == null) {
super.onBackPressed();
}
if (currentFrag != null) {
if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.CHAT_FRAGMENT.toString())) {
if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
openDrawer(false);
} else
requestBeginTransaction(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString(), true, false);
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.BILLBOARD_FRAGMENT.toString())) {
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.NEWS_FRAGMENT.toString())) {
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.INFO_FRAGMENT.toString())) {
super.onBackPressed();
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.SEARCH_FRAGMENT.toString())) {
// exit app if the search address view is visible
if (currentFrag.getView().findViewById(R.id.search_address_layout).getVisibility() == View.VISIBLE) {
exitApp();
} else if (currentFrag.getView().findViewById(R.id.show_search_result_layout).getVisibility() == View.VISIBLE) {
// show search address view if Address already exist view is visible
currentFrag.getView().findViewById(R.id.search_address_layout).setVisibility(View.VISIBLE);
currentFrag.getView().findViewById(R.id.history).setVisibility(View.VISIBLE);
currentFrag.getView().findViewById(R.id.show_search_result_layout).setVisibility(View.INVISIBLE);
((SearchFragment)currentFrag).onSearchLayoutVisible();
}
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.PREFERENCE_FRAGMENT.toString())) {
super.onBackPressed();
//requestBeginTransaction(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString(), true, false);
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.PREFERENCE_FRAGMENT_CHAT_SETTINGS.toString())) {
super.onBackPressed();
//requestBeginTransaction(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString(), true, false);
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.PREFERENCE_FRAGMENT_THEME_SETTINGS.toString())) {
super.onBackPressed();
//requestBeginTransaction(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString(), true, false);
} else if (currentFrag.getTag().equals(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString())) {
super.onBackPressed();
//requestBeginTransaction(SettingsManager.FragmentsModel.LAUNCHER_FRAGMENT.toString(), true, false);
}
} else
exitApp();
}
在上面的代碼我彈出片段和不知道片段是什麼下這是發生什麼事popt片段。
這是當我添加或顯示片段
/**
* Change the current displayed fragment by a new one.
* - if the fragment is in backstack, it will pop it
* - if the fragment is already displayed (trying to change the fragment with the same), it will not do anything
*
* @param backStateName the new fragment to display
* @param saveInBackstack if we want the fragment to be in backstack
* @param animate if we want a nice animation or not
*/
public void requestBeginTransaction(String backStateName, boolean saveInBackstack, boolean animate) {
Fragment frag = null;
if (mFragManager.findFragmentByTag(backStateName) != null) {
frag = mFragManager.findFragmentByTag(backStateName);
} else
try {
frag = (Fragment) Class.forName(backStateName).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
FragmentManager manager = getSupportFragmentManager();
boolean fragmentPopped = manager.popBackStackImmediate(backStateName, 0);
if (!fragmentPopped && manager.findFragmentByTag(backStateName) == null) {
//fragment not in back stack, create it.
FragmentTransaction transaction = manager.beginTransaction();
if (animate) {
LogManager.d(this, "Change Fragment: animate");
// transaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left, R.anim.slide_in_left, R.anim.slide_out_right);
}
transaction.add(R.id.frame, frag, backStateName);
if (saveInBackstack) {
LogManager.d(this, "Change Fragment: addToBackTack " + backStateName);
transaction.addToBackStack(backStateName);
LogManager.d(this, "Change Fragment: NO addToBackTack");
}
transaction.commit();
} else {
mFragManager.beginTransaction().show(mFragManager.findFragmentByTag(backStateName)).commit();
// custom effect if fragment is already instanciated
}
} catch (IllegalStateException exception) {
LogManager.w(this, "Unable to commit fragment, could be activity as been killed in background. " + exception.toString());
}
}
您可以檢查isAttached（）; – AnixPasBesoin