In my application i have a FragmentPager. Now each Fragment has a next button with which i navigate to the next fragment. Via the next button i know that the user is navigation away from the view. But how do i know if the user has clicked on the tabs. Will the
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(KEY_CONTENT, mContent);
}
function be called when a user presses a different tab ? Can i save the state and restore it on the
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if ((savedInstanceState != null)
&& savedInstanceState.containsKey(KEY_CONTENT)) {
mContent = savedInstanceState.getString(KEY_CONTENT);
}
}
will this work ? What other way can i know that the user has clicked on the different tab ?
Kind Regards
First of all, are you using ActionBarSherlock for you actionbar/tabs? I recommend that you do since you'll get a cross-version way of working with the actionbar.
In any case, you should add a listener to each tab before adding it to the actionbar. With the listener implemented you know when a tab has been selected, reselected and unselected
I'm not sure about when the onSaveInstanceState is called (try it using the debugger!), but with the listener implemented you'll get a fool-proof way of knowing what goes on with your tabs.
Related
I have two Fragments in my ViewPager as Tabs. These share a toolbar. You get to the SettingsActivity by clicking an Icon on the toolbar.
So you can access the SettingsActivity while either Fragment A is the visible one, or Fragment B is the visible one.
When I navigate back from the SettingsActivity to the fragments, by clicking the Up Button in the toolbar (actionBar.setDisplayHomeAsUpEnabled(true);), I want to have the fragment visible, that I had visible when I accessed SettingsActivity.
Without any special code (= current state) it seems to always return to the first Fragment in the ViewPager (i.e. the most left one).
Parent Activity for the Up Navigation is MainActivity, where I have the ViewPager with the 2 Fragments as Tabs.
Use the state saving callback to save the state of your MainActivity:
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("SELETED_TAB_INDEX", mSelectedTabIndex);
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null) { // so the activity is being restarted
pager.setCurrentItem(savedInstanceState.getInt("SELETED_TAB_INDEX"));
}
}
save your fragment to backstack. This way, back button for fragments would work same as it runs for activities.
Here: http://developer.android.com/training/implementing-navigation/temporal.html
I'm having some problems with navigation and the up button of the activity. I have two tabs implemented with Viewpager in one activity and then another activity which is loaded from the previous one. When the user clicks the phone's back button or the activity's up button, I want to go back to the previously selected tab and fragment of the first activity.
So far I've been able to do it for the back button, with onSaveInstanceState and the following code:
#Override
protected void onSaveInstanceState(Bundle bundle) {
super.onSaveInstanceState(bundle);
bundle.putInt("currentPage", mViewPager.getCurrentItem());
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null) {
int page = savedInstanceState.getInt("currentPage", 0);
mViewPager.setCurrentItem(page);
getSupportActionBar().setSelectedNavigationItem(page);
}
}
Why is this not working for the up button? What do I have to do?
Any help is appreciated and sorry if this is an issue easy to solve, but I'm rather new to the Android programming.
I finally found the solution at Returning from an activity using navigateUpFromSameTask(). savedInstanceState was null when the activity was recreated. To avoid so, the launch mode of the activity has to be declared as singleTop in the Android manifest.
When the action bar has tabs, I've noticed that onTabSelected is called when the activity loads on screen. It also is being called whenever an orientation change occurs. My code queries the database depending on the tab being selected, and displays the query results to the loaded layout.
My problem is when saving tab state, and the current selected tab is 1 or higher, on restore state, since onTabSelected is called by default on the 0 tab, it will be called again when restored state tab is 1 or higher. This makes database query on tab 0 useless.
How to configure android that onTabSelected isn't called on tab creation or at least detect that this call is default and not user triggered?
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
int tabPos = tab.getPosition();
switch(tabPos) {
case 0:
// query database and display result
break;
case 1:
// a different query and display result
break;
case 2: ...
}
}
#Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
if(savedInstanceState.containsKey(STATE_SELECTED_TAB)) {
getActionBar().setSelectedNavigationItem(savedInstanceState.getInt(STATE_SELECTED_TAB));
}
super.onRestoreInstanceState(savedInstanceState);
}
#Override
public void onSaveInstanceState(Bundle outState) {
outState.putInt(STATE_SELECTED_TAB, getActionBar().getSelectedNavigationIndex());
super.onSaveInstanceState(outState);
}
Added complication:
When the current selected tab is 0, and the orientation changes, onTabSelected is still called twice! Once when the tabs are initially created, and 2nd time when onRestoreState restores the saved tab selected state, even though it is 0.
What I originally supposed was that onTabSelected was called twice, but I was mistaken. It was my fragment onCreateView being called twice, some errors in fragment transaction that added the same fragment twice on orientation change. onTabSelected is called once, and restore state calls onTabReselected is called too when the restored tab is also 0.
After scouring SO and google, I've found this question to have similar cause of problem.
Creating ActionBar tab also calling its selectTab functions
So after reviewing the reference docs on ActionBar from Google's Android site, addTab method is the one responsible for calling onTabSelected by default.
public abstract void addTab (ActionBar.Tab tab)
Add a tab for use in tabbed navigation mode. The tab will be added at the end of the list. If this is the first tab to be added it will become the selected tab.
Parameters
tab Tab to add
Incidentally, other overloaded methods exist that do not call onTabSelected.
public abstract void addTab (ActionBar.Tab tab, boolean setSelected)
So I used these alternative methods instead and it fixed the problem.
However, once the tabs are displayed, the first tab may appear selected even though it's not. Clicking on it will call onTabSelected and not onTabReselected.
I solved it in this way:
Call setupWithViewPager before tabLayout.addOnTabSelectedListener
tabLayout.setupWithViewPager(viewPager)
tabLayout.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
override fun onTabSelected(tab: TabLayout.Tab?) {....}
.....
}
because when you call setupWithViewPager, this will internally call
setOnTabSelectedListener(new
ViewPagerOnTabSelectedListener(viewPager));
so you better call it before adding tabSelect Listener to tabLayout
i think you can do this (and ignore any typo please :-)) :
public class MainActivity extends FragmentActivity {
boolean isConfigChanged;
int savedTabIndex;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState != null){
if(savedInstanceState.containsKey(STATE_SELECTED_TAB)) {
savedTabIndex = savedInstanceState.getInt(STATE_SELECTED_TAB);
//getActionBar().setSelectedNavigationItem(savedTabIndex); actually you do not need this
}
isConfigChanged = true;
}
// here add actionbar tabs
//...}
and in :
below code checks that if configuration changes and the user selected tab is not zero so this is default call and ignore but if isConfigChanged == true and the user selected tab is 0 you must query DB or if isConfigChanged == false you must query DB because it is first time that app is loading. a quick play may fit it to what you want.
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if(isConfigChanged && savedTabIndex != 0){
isConfigChanged = false;
return;
}
isConfigChanged = false;
int tabPos = tab.getPosition();
switch(tabPos) {
case 0:
// query database and display result
break;
case 1:
// a different query and display result
break;
case 2: ...
}
}
remove onRestore
#Override
public void onSaveInstanceState(Bundle outState) {
outState.putInt(STATE_SELECTED_TAB, getActionBar().getSelectedNavigationIndex());
super.onSaveInstanceState(outState);
}
I am new to fragments and have a lot of problems understanding and working with them. I will try to describe my problem step by step:
I start with a list
after selecting an item i start an activity with a dynamic url in a webview
If portrait, only the webview is showed, if landscape the list is presented next to it
In landscape when i select another item, it is showd in the webview (check the code)
Problem: When i turn back now to portrait the first selected item is showd instead of the last one.
How can i update the activity so it will keep the last opened url after orientation change?
if (fragment==null || ! fragment.isInLayout()) {
Intent intent = new Intent(this.getActivity(), DetailViewActivity.class);
intent.putExtra("link", urlforwebview);
startActivity(intent);
} else {
DetailView detailFragment =
(DetailView)
getFragmentManager().findFragmentById(R.id.detailfragment);
detailFragment.changeWebviewURL(urlforwebview);
}
FIX:
Added this to my detailfragment:
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("currentUrl", url);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (savedInstanceState != null) {
// Restore last state for checked position.
url = savedInstanceState.getString("currentUrl", "");
changeWebviewURL(url);
}
}
Have a look at : onSaveInstanceState.
http://developer.android.com/reference/android/app/Activity.html#onSaveInstanceState(android.os.Bundle)
This answer here can help you: android fragment- How to save states of views in a fragment when another fragment is pushed on top of it
I'm using action bar tab navigation and when I rotate screen I get IndexOutOfBoundsException
According to logcat problem is in getSupportActionBar().setSelectedNavigationItem(
savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
#Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
// Restore the previously serialized current tab position.
if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
getSupportActionBar().setSelectedNavigationItem(
savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
}
}
#Override
public void onSaveInstanceState(Bundle outState) {
// Serialize the current tab position.
outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getSupportActionBar()
.getSelectedNavigationIndex());
}
EDIT
I found the problem. I use AsyncTask to gather all info that will be showed in tabs and I add tabs in onPostExecute.
onRestoreInstanceState is called before onPostExecute so the tab count is still 0.
Try
if (savedInstanceState!= null && savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM) >= 0)
instead if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM))
I'm not sure if onSaveInstanceState is called when the screen is rotated.
Due to this documentation "the method onSaveInstanceState(Bundle) is called before placing the activity in such a background state".
Did you check, whether the function is called when the screen is rotated?