我有一个列出人员的片段。它在一个（Main）Activity中调用，它在PeopleListFragment之前启动。按下后退按钮，整个应用程序完成。我需要转到主活动而不是关闭.I很困惑，是否使用PopBackStack（），PopBackStackimmediate（）或OnBackPressed（）。有人可以帮我这个..？
PeopleListFragment
public class PeopleListFragment extends Fragment implements PeopleController.PeopleListView, SearchView.OnQueryTextListener {
private static final String TAG = "PeopleListFragment";
public static final boolean DEBUG = Constant.DEBUG;
private static final String EXTRA_EMPLOYEE_ID = "employeeId";
private static final String EXTRA_FIRST_NAME = "firstName";
private static final String EXTRA_LAST_NAME = "lastName";
private ProgressDialog progressDialog;
private ArrayList<People> contactList = new ArrayList<>();
private ListView mContactlistView;
Parcelable state;
private Intent intent;
private PeopleAdapter adapter;
/**
* Passes the value to another activity/fragment
*
* @param employeeId
* @param firstName
* @param lastName
* @return
*/
public static PeopleListFragment newInstance(String employeeId, String firstName, String lastName) {
PeopleListFragment fragment = new PeopleListFragment();
Bundle args = new Bundle();
args.putString(EXTRA_EMPLOYEE_ID, employeeId);
args.putString(EXTRA_FIRST_NAME, firstName);
args.putString(EXTRA_LAST_NAME, lastName);
fragment.setArguments(args);
return fragment;
}
public PeopleListFragment() {
// Required empty public constructor
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
contactList = new ArrayList<>();
//Initializing the People controller
PeopleController.getInstance(getActivity()).addPeopleListCallback(this);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflating the layout for people list fragment
return inflater.inflate(R.layout.fragment_people_list, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mContactlistView = (ListView) view.findViewById(R.id.people_list);
mContactlistView.setAdapter(adapter);
if (state != null) {
Log.d(TAG, "Restoring list view state");
mContactlistView.requestFocus();
mContactlistView.onRestoreInstanceState(state);
}
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
adapter = new PeopleAdapter(getActivity().getApplicationContext(),
R.layout.people_list_item, contactList);
mContactlistView.setAdapter(adapter);
mContactlistView.setTextFilterEnabled(false);
mContactlistView.setFastScrollEnabled(true);
mContactlistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String empId = String.valueOf(adapter.getItem(position).getEmployeeId());
String fname = String.valueOf(adapter.getItem(position).getFirstName());
String lname = String.valueOf(adapter.getItem(position).getLastName());
intent = new Intent(getActivity(),
PeopleDetailsActivity.class);
intent.putExtra("EmployeeId", empId);
intent.putExtra("fName", fname);
intent.putExtra("lName", lname);
startActivity(intent);
}
});
}
public void updateListView(ArrayList<People> peopleList) {
contactList = peopleList;
adapter.updateItems(contactList);
if (contactList.size() == 0) {
if (DEBUG) {
Log.i(TAG, "Contact List is Empty");
}
if (progressDialog.isShowing()) {
progressDialog.dismiss();
}
} else {
mContactlistView.setVisibility(View.VISIBLE);
}
}
@Override
public void showProgress() {
if (progressDialog != null) {
progressDialog.show();
mContactlistView.setVisibility(View.GONE);
}
}
@Override
public void hideProgress() {
if (progressDialog != null) {
progressDialog.dismiss();
}
}
@Override
public void displayPeopleList(ArrayList<People> peoples) {
updateListView(peoples);
}
@Override
public void updatePeopleList(ArrayList<People> peoples) {
updateListView(peoples);
}
@Override
public void onStart() {
super.onStart();
PeopleController.getInstance(getActivity()).getPeople();
}
@Override
public void onResume() {
super.onResume();
PeopleController.getInstance(getActivity()).onResume();
}
@Override
public void onPause() {
super.onPause();
PeopleController.getInstance(getActivity()).onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
PeopleController.getInstance(getActivity()).removePeopleListCallback();
}
@Override
public void showError(int errorCode) {
if (errorCode == NetworkClient.HTTP_UNAUTHORIZED_SESSION) {
logout();
} else if (errorCode == NetworkClient.FAILURE) {
if (contactList.size() == 0) {
Toast.makeText(getActivity().getApplicationContext(), "Empty Contact List",
Toast.LENGTH_LONG).show();
} else {
//show sync warning
Snackbar.make(mContactlistView, R.string.info_no_event,
Snackbar.LENGTH_SHORT)
.show();
}
} else if (errorCode == NetworkClient.NO_INTERNET_CONNECTION) {
if (contactList.size() == 0) {
Toast.makeText(getActivity().getApplicationContext(), "No Internet Connection",
Toast.LENGTH_LONG).show();
}
}
}
protected void logout() {
if (getActivity() != null && getActivity() instanceof BaseActivity) {
((BaseActivity) getActivity()).logout();
}
}
public void search(String searchText) {
adapter.getFilter().filter(searchText);
}
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
search(newText);
return true;
}
/**
* In this method the search interface is setup for searching a particular employee
*
* @param menu
* @return
*/
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
super.onCreateOptionsMenu(menu, inflater);
inflater = getActivity().getMenuInflater();
inflater.inflate(R.menu.options_menu, menu);
SearchManager searchManager = (SearchManager) getActivity().getSystemService(Context.SEARCH_SERVICE);
SearchView searchView = (SearchView) menu.findItem(R.id.search).getActionView();
searchView.setSearchableInfo(searchManager.getSearchableInfo(getActivity().getComponentName()));
searchView.setIconifiedByDefault(false);
searchView.setOnQueryTextListener(this);
}
}
MainActivity
public class MainActivity extends BaseActivity {
protected static final int NAVDRAWER_ITEM_HOME = 0;
protected static final int NAVDRAWER_ITEM_PEOPLE = 1;
protected static final int NAVDRAWER_ITEM_CALENDAR = 2;
protected static final int NAVDRAWER_ITEM_TRAINING = 3;
protected static final int NAVDRAWER_ITEM_ANNOUNCEMENT = 4;
protected static final int NAVDRAWER_ITEM_INVALID = -1;
private DrawerLayout mDrawerLayout;
Intent intent;
/**
* List of Title for each {@link NavigationView} item
*/
private static final int[] NAVDRAWER_TITLE_RES_ID = {
R.string.app_name,
R.string.people,
R.string.calendar,
R.string.training,
R.string.announcement
};
/**
* Primary color list for each {@link NavigationView} item
*/
private static final int[] NAVDRAWER_PRIMARY_COLOR_RES_ID = {
R.color.trainingPrimaryColor,
R.color.peoplePrimaryColor,
R.color.calendarPrimaryColor,
R.color.trainingPrimaryColor,
R.color.announcementPrimaryColor
};
/**
* Status bar color list for each {@link NavigationView} item
*/
private static final int[] NAVDRAWER_PRIMARY_DARK_COLOR_RES_ID = {
R.color.trainingPrimaryDarkColor,
R.color.peoplePrimaryDarkColor,
R.color.calendarPrimaryDarkColor,
R.color.trainingPrimaryDarkColor,
R.color.announcementPrimaryDarkColor
};
FragmentManager fragmentManager;
private PeopleListFragment mPeopleListFragment;
private AnnouncementListFragment mAnnouncementListFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getSelfNavDrawerItem() > 0) {
setTitle(NAVDRAWER_TITLE_RES_ID[getSelfNavDrawerItem()]);
setToolbarBackgroundColor(NAVDRAWER_PRIMARY_COLOR_RES_ID[getSelfNavDrawerItem()]);
setStatusBarColor(NAVDRAWER_PRIMARY_DARK_COLOR_RES_ID[getSelfNavDrawerItem()]);
// sendScreenName(getString(NAVDRAWER_TITLE_RES_ID[getSelfNavDrawerItem()]));
}
initNavDrawer();
}
/**
* Initialize {@link NavigationView} and set Listener for the View
*/
private void initNavDrawer() {
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
if (mDrawerLayout == null) {
return;
}
//To display Menu
NavigationView mNavigationView = (NavigationView) findViewById(R.id.navigation_view);
// To preserve original icon color in NavigationView
mNavigationView.setItemIconTintList(null);
ActionBarDrawerToggle mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
getToolbar(), R.string.open, R.string.close) {
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
}
@Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
}
};
mDrawerLayout.addDrawerListener(mDrawerToggle);
mDrawerToggle.syncState();
mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem item) {
mDrawerLayout.closeDrawers();
int itemId = NAVDRAWER_ITEM_INVALID;
switch (item.getItemId()) {
case R.id.home:
itemId = NAVDRAWER_ITEM_HOME;
break;
case R.id.people:
itemId = NAVDRAWER_ITEM_PEOPLE;
break;
case R.id.calendar:
itemId = NAVDRAWER_ITEM_CALENDAR;
break;
case R.id.training:
itemId = NAVDRAWER_ITEM_TRAINING;
break;
case R.id.announcement:
itemId = NAVDRAWER_ITEM_ANNOUNCEMENT;
break;
}
onNavDrawerItemClicked(itemId);
return false;
}
});
NavigationMenuView navigationMenuView = (NavigationMenuView) mNavigationView.getChildAt(0);
//Add a Divider between Menu Items in NavigationView
navigationMenuView.addItemDecoration(new LineDividerItemDecoration(this, R.drawable.line_divider,
1));
}
/**
* It return which Navigation view item it displaying/active, if activity does not
* contain {@link NavigationView} it'll return {@link #NAVDRAWER_ITEM_INVALID}
*
* @return Navigation Item ID
*/
protected int getSelfNavDrawerItem() {
return NAVDRAWER_ITEM_INVALID;
}
/**
* When {@link NavigationView} item click it'll be called
*
* @param itemId Id of clicked item
*/
private void onNavDrawerItemClicked(final int itemId) {
if (itemId == getSelfNavDrawerItem()) {
//if current Navigation Item is clicked again don't do anything simply close the
// Drawerlayout
mDrawerLayout.closeDrawer(GravityCompat.START);
return;
}
goToNavDrawerItem(itemId);
mDrawerLayout.closeDrawer(GravityCompat.START);
/*mHandler.postDelayed(new Runnable() {
@Override
public void run() {
goToNavDrawerItem(itemId);
}
}, NAVDRAWER_LANUCH_DELAY);
View mainContent = findViewById(R.id.main_content);
if (mainContent != null) {
mainContent.animate().alpha(0).setDuration(MAIN_CONTENT_FADEOUT_DURATION).start();
}*/
}
/**
* Start New Activity for clicked item
*
* @param itemId Id of clicked item
*/
private void goToNavDrawerItem(int itemId) {
Fragment fragment = null;
Class fragmentClass = null;
Intent intent = null;
switch (itemId) {
case NAVDRAWER_ITEM_HOME:
intent = new Intent(this, HomeActivity.class);
fragmentClass = HomeFragment.class;
//to clear the activity stack to avoid showing previous activity by pressing back key
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
break;
case NAVDRAWER_ITEM_PEOPLE:
setTitle("People");
setStatusBarColor(R.color.peoplePrimaryDarkColor);
setToolbarBackgroundColor(R.color.peoplePrimaryColor);
fragmentClass = PeopleListFragment.class;
break;
case NAVDRAWER_ITEM_CALENDAR:
//Calendar fragment
break;
case NAVDRAWER_ITEM_TRAINING:
//Training fragment
break;
case NAVDRAWER_ITEM_ANNOUNCEMENT:
setTitle("Announcement");
setStatusBarColor(R.color.announcementPrimaryDarkColor);
setToolbarBackgroundColor(R.color.announcementPrimaryColor);
fragmentClass = AnnouncementListFragment.class;
break;
}
try {
fragment = (Fragment) (fragmentClass != null ? fragmentClass.newInstance() : null);
} catch (Exception e) {
e.printStackTrace();
}
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.display_frame_container, fragment).commit();
mDrawerLayout.closeDrawers();
if (intent != null) {
startActivity(intent);
}
//To cancel the transition animation
overridePendingTransition(0, 0);
}
@Override
protected int getLayoutResourceId() {
return R.layout.activity_main;
}
}
基本活动
public abstract class BaseActivity extends AppCompatActivity
implements TrainingListFragment.TrainingCallback {
/**
* Drawer Layout for creating {@link NavigationView}
*/
private Handler mHandler;
/**
* Toolbar
*/
private Toolbar mToolbar;
/**
* Google Analytical Tracker
*/
private Tracker mTracker;
/*private static final int NAVDRAWER_LANUCH_DELAY = 250;
private static final int MAIN_CONTENT_FADEOUT_DURATION = 250;*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getLayoutResourceId());
String session = PreferenceUtil.getInstance(this).getSession();
if (TextUtils.isEmpty(session)) {
logout();
}
mToolbar = (Toolbar) findViewById(R.id.main_toolbar);
setSupportActionBar(mToolbar);
//Initialize the Google Analytical Tracker
mTracker = ((INetApplication) getApplication()).getDefaultTracker();
mHandler = new Handler();
}
/**
* Send Current Activity Name to Google Analytics
*
* @param screenName Name of the Current Screen
*/
protected void sendScreenName(String screenName) {
mTracker.setScreenName("Activity~" + screenName);
mTracker.send(new HitBuilders.ScreenViewBuilder().build());
}
/**
* Send Calendar Event to Google Analytics
*
* @param value Selected Date
*/
protected void sendCalendarEventToAnalytics(String value) {
String CATEGORY_CALENDAR = "Calendar";
String ACTION_SELECT_DATE = "Select Date";
mTracker.send(new HitBuilders.EventBuilder()
.setCategory(CATEGORY_CALENDAR)
.setAction(ACTION_SELECT_DATE)
.setLabel(value).build());
}
/**
* To clear the User session and display the Login screen
*/
public void logout() {
//clear the session and employee id value from preference
PreferenceUtil.getInstance(this).setSession("");
PreferenceUtil.getInstance(this).setEmpId("");
Intent loginIntent = new Intent(this, LoginActivity.class);
//to clear the activity stack to avoid showing previous activity by pressing back key
loginIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(loginIntent);
finish();
}
/**
* It will give the Layout Resource ID
*
* @return int value of Layout Resource
*/
protected abstract
@LayoutRes
int getLayoutResourceId();
@Override
protected void onPause() {
super.onPause();
//To cancel the transition animation
overridePendingTransition(0, 0);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
/*View mainContent = findViewById(R.id.main_content);
if (mainContent != null) {
mainContent.setAlpha(0);
mainContent.animate().alpha(1).setDuration(MAIN_CONTENT_FADEOUT_DURATION).start();
}*/
}
/**
* To enable/disable HomeUp option in {@link Toolbar}
*
* @param isHomeDisplay boolean to change the HomeUp option
*/
public void setHomeUpEnable(boolean isHomeDisplay) {
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(isHomeDisplay);
getSupportActionBar().setHomeButtonEnabled(isHomeDisplay);
Drawable backArrowDrawable = ContextCompat.getDrawable(this,
android.support.design.R.drawable.abc_ic_ab_back_material);
backArrowDrawable.setColorFilter(Color.WHITE, PorterDuff.Mode.SRC_ATOP);
getSupportActionBar().setHomeAsUpIndicator(backArrowDrawable);
}
}
/**
* To change the background color of {@link Toolbar}
*
* @param colorValue color value
*/
public void setToolbarBackgroundColor(@ColorRes int colorValue) {
mToolbar.setBackgroundColor(ContextCompat.getColor(this, colorValue));
}
/**
* To change the statusbarcolor
*
* @param colorValue color value
*/
public void setStatusBarColor(@ColorRes int colorValue) {
UIUtil.getInstance(this).setStatusBarColor(ContextCompat.getColor(this, colorValue));
}
/**
* Set the title of this {@link #mToolbar}.
*
* @param title title value in string
*/
public void setTitle(String title) {
mToolbar.setTitle(title);
}
/**
* Set the title of this {@link #mToolbar}.
*
* @param title a string resource
*/
public void setTitle(@StringRes int title) {
mToolbar.setTitle(title);
}
public Toolbar getToolbar() {
return mToolbar;
}
@Override
public void onTrainingItemClick(String trainingId, String trainingTitle, boolean joinStatus,
String trainingTime) {
Intent intent = new Intent(this, TrainingDetailActivity.class);
intent.putExtra(TrainingDetailFragment.EXTRA_ID, trainingId);
intent.putExtra(TrainingDetailFragment.EXTRA_TITLE, trainingTitle);
intent.putExtra(TrainingDetailFragment.EXTRA_JOINED_STATUS, joinStatus);
intent.putExtra(TrainingDetailFragment.EXTRA_TRAINING_TIME, trainingTime);
startActivity(intent);
}
@Override
public void displayInfoView(int displayCode) {
}
}
答案 0 :(得分：0)
如果您使用堆栈来维护您的片段，那么使用堆栈弹出片段，直到您的堆栈大小变为1
while(getParent().stackSize() >2) {
getParent().popFragments();
}
答案 1 :(得分：0)
要替换片段，请使用以下代码
@Override
public void replaceFragment(Fragment fragment, String title) {
String backStateName = fragment.getClass().getName();
FragmentManager manager = getSupportFragmentManager();
boolean fragmentPopped = manager.popBackStackImmediate(backStateName, 0);
if (!fragmentPopped) { //fragment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.container_body, fragment);
ft.addToBackStack(backStateName);
ft.commit();
// getSupportActionBar().setDisplayShowTitleEnabled(false);
getSupportActionBar().setTitle("");
}
}
使用此代码添加片段
在Fragment onCreateView
中添加以下行 setHasOptionsMenu(true);
使用以下代码返回上一个片段。
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
if (getActivity().getSupportFragmentManager().getBackStackEntryCount() > 1) {
getFragmentManager().popBackStack();
return true;
}
return true;
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public void onDetach() {
super.onDetach();
if (getActivity().getSupportFragmentManager().getBackStackEntryCount() > 1) {
getFragmentManager().popBackStack();
}
}
答案 2 :(得分：0)
您需要将事务添加到backstack，然后才会将片段加载。
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.display_frame_container, fragment).commit();
这个
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.display_frame_container, fragment).addToBackStack("").commit();
当您按下后退按钮时，它将自动转到MainActivity