My application structure look like:
SplashActivity -> MainActivity -> (switching between many fragments)
What I expect: finish application from main activity when fragment back stack count is zero. Here is my try:
In SplashAcitivty
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getIntent().getBooleanExtra("exit", false)) {
finish();
}
}
In MainActivity:
#Override
public void onBackPressed() {
// I need to implement this method
if( backstackCount() == 0){
Intent intent = new Intent(this, SplashActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.putExtra(SplashActivity.EXIT_KEY, true);
startActivity(intent);
}else{
super.onBackPressed();
}
}
So, please tell me how can I determine the back stack when it 's empty? Because I use SlideMenu library, all of my fragments switch many times, and they are added to back stack when switching. Look like this one:
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content_frame, fragment)
.addToBackStack(null)
.commit();
Here is my code. It works fine for me:
#Override
public void onBackPressed() {
int backStackEntryCount = getSupportFragmentManager().getBackStackEntryCount();
if (backStackEntryCount == 0) {
goBack(); // write your code to switch between fragments.
} else {
super.onBackPressed();
}
}
Related
how to implement press back again to exit in android studio, Pls. see My coding here. i'd checked all discussions here regarding this, but not working with my code. i've to make sure On back pressed, always go to home fragment before closing.
Thank you very much in advance!
/**
* On back pressed, always go to home fragment before closing
*/
#Override
public void onBackPressed() {
//if stack has items left
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
//get current fragment
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.mainFragment);
//only close if in CategoryFragment else go to CategoryFragment
if (fragment instanceof SearchFragment) {
finish();
} else {
changeFragment(new SearchFragment());
}
} else {
super.onBackPressed();
}
}
OnBackPress
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
finish()
If you wanna make onBackPressed again to exit activity you can use this
public void onBackPressed() {
count++;
if (count > 1) {
moveTaskToBack(true);
} else {
showToast("Press back again to Leave!");
// resetting the counter in 2s
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
count = 0;
}
}, 2000);
}
}
I used an activity and several pieces in my app
sometimes when I'm on the first page (activity) and back pressed not going out of app and returns to the fragment or the same page
When this happens I've done a lot of work in the program
I used this code to fix this problem but
it also applied to the fragments
#Override
public void onBackPressed() {
this.finish();
}
Why returns to the fragment or the same page
How this problem is solved
I'm using this now
boolean doubleBackToExitPressedOnce = false;
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else if (!doubleBackToExitPressedOnce) {
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Click to exit again", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 2000);
} else {
super.onBackPressed();
return;
}
}
Way is going to be a fragment
TabirFragment tabirFragment = new TabirFragment();
Bundle bundle = new Bundle();
bundle.putInt("id", id);
bundle.putString("name", name);
tabirFragment.setArguments(bundle);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction().addToBackStack(null);
transaction.replace(R.id.main_activity, tabirFragment).commit();
If you have multiple activities on the stack, then:
finish() - finishes the activity where it is called from and you see
the previous activity.
There is also system.exit but that would not work in your case:
System.exit(0) - restarts the app with one fewer activity on the
stack. So, if you called ActivityB from ActivityA, and System.exit(0)
is called in ActivityB, then the application will be killed and
started immediately with only one activity ActivityA
I recommend you use finishAffinity(). It will finish the current activity as well as all activities immediately below it. I remind you that it is supported by only API level 16+
several pieces what? fragments, getting trouble to understand, anyway if you want to manage frag and onBackPress, use this
private void setUpBackStackListener() {
getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
Fragment currentFragment = getFragmentManager().findFragmentById(R.id.am_frameLayout);
if (currentFragment != null) {
int myCount = getFragmentManager().getBackStackEntryCount();
if (LOG_DEBUG) Log.e(TAG, "backStackCount : " + myCount);
String currentFragName = currentFragment.getClass().getSimpleName();
if (currentFragName.equalsIgnoreCase(FragOne.class.getSimpleName())) {
shouldExit = true;
} else if (currentFragName.equalsIgnoreCase(FragTwo.class.getSimpleName())) {
shouldExit = false;
}
}
}
}
});
}
#Override
public void onBackPressed() {
if (shouldExit == true) {
if (LOG_DEBUG)
Log.e(TAG, " Yeah exit douche:" + shouldExit + " isLastEntry : Testing :" + isLastEntry);
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
,if this not you seeking, you might want to clear what you want in a bit subtle way
When you used multiple fragment and activity When you switch activity by using method startActivity(), always use method finish(); when you back pressed then you will never get multiple activity and fragment and use onBackPressed method on main activity.
boolean doubleBackToExitPressedOnce=false;
#Override
public void onBackPressed() {
//Checking for fragment count on backstack
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else if (!doubleBackToExitPressedOnce) {
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this,"Please click back again to exit.", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 2000);
} else {
super.onBackPressed();
return;
}
}
The easiest solution i can give you is to keep no-history for the activity in the manifest file. and then override the back method for each activity.
<activity
android:name=".example"
android:noHistory="true">
</activity>
i have activity1 takes me to activity2 that takes me to fragment. i would like from fragment to go back to activity2
public void onBackPressed() {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
}
else
super.onBackPressed();
}
While adding fragment from activity2 add it to backstack like this
getSupportFragmentManager().beginTransaction()
.replace(R.id.frame_layout, new SampleFragment())
.addToBackStack(SampleFragment.class.getSimpleName())
.commit();
And onBackPressed check if the fragment is present in backstack and pop it
#Override
public void onBackPressed() {
if(getSupportFragmentManager().getBackStackEntryCount()>0){
Fragment fragment=getSupportFragmentManager().findFragmentById(R.id.YOUR_FRAME_LAYOUT_ID);
if(fragment!=null && fragment.getClass().getSimpleName().equalsIgnoreCase(SampleFragment.class.getSimpleName())){
getSupportFragmentManager().popBackStackImmediate();
}
}else {
super.onBackPressed();
}
}
on fragments get the backpressed event and there call the
getactivity().getsupportfragmentmanager().popbackstack();
Add that fragment transaction to backstack.
Navigation drawer with fragments. I have placed one fragment on main activity. But if i back press the same fragment comes again. How can I handle this??
and secondly how to implement onBackpressed in fragments??
Can anybody help me out?
in onCreate of main activity I have
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment());
tx.commit();
and in back press of it I have
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
First you need to add the fragmnet to back stack so we could retrieve it later in onBackPressed()
Replace your fragmnet transaction with this
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment());
// HERE WE WILL ADD FRAGMENT TO BACKSTACK SO WE COULD GET BACK TO IT
tx.addToBackStack(null);
tx.commit();
Replace your onBackPressed with this
#Override
public void onBackPressed() {
// CHECKS HOW MANY FRAGMENTS ARE IN THE BACKSTACK
int count = getFragmentManager().getBackStackEntryCount();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if (count == 0) {
// IF NO FRAGMENT IN THE BACKSTACK CALL
super.onBackPressed();
} else {
// GET THE LAST OPENED FRAGMENT
getFragmentManager().popBackStack();
}
}
}
You can do this using Interface. That interface will implemented in each fragment. Here is a simple example:
public interface OnBackPressedListener {
void onBackPressed();
}
Here, if you implement this interface in your fragment then you will found this method:
#Override
public void onBackPressed() {
getActivity().finish(); // Or Do your specific task
}
Now your Activity that holds that fragment , that should use onBackPressed() callback. Write bellow code in that method
#Override
public void onBackPressed() {
if (YOUR_DRAWER.isDrawerOpen(GravityCompat.START)) {
YOUR_DRAWER.closeDrawer(Gravity.LEFT); //CLOSE Nav Drawer!
return;
}
Fragment fragment=getYourVisibleFragment();
if(fragment!=null){
((OnBackPressedListener)fragment).onBackPressed();
}else{
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
}
If you want to get Visible fragment then just use this method
public <F extends Fragment> F getVisibleFragment() {
List<Fragment> fragments = getSupportFragmentManager().getFragments();
if (fragments != null) {
for (Fragment fragment : fragments) {
if (fragment != null && fragment.isVisible()) {
return (F) fragment;
}
}
}
return null;
}
That's it :)
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment()).addToBackStack("your tag");
tx.commit();
Override onBackPress() and try following code.
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
//your other utility code if needed
} else {
getFragmentManager().popBackStack();
}
}
Hope this will work for you.
Replace ypu fragment in onCreate with fragment id , and then implement onBackpressed on the same activity and find that fragment with id and check is it visible or null and then perform operations based on it.
hope you got this.
I have an Activity with two Fragments (List & Details), in onCreate(), I start the List Fragment if savedInstance is null like so
public static final int CLIENT_LIST_FRAGMENT = 1;
public static final int CLIENT_DETAILS_FRAGMENT = 2;
private int currentFragment = 0;
if (savedInstanceState == null) {
//On first run, start the list fragment
if (currentFragment == 0) {
ClientListFragment listFrag = new ClientListFragment();
getSupportFragmentManager().beginTransaction()
.add(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
} else {
switch (currentFragment) {
case CLIENT_LIST_FRAGMENT:
addListFragment();
break;
case CLIENT_DETAILS_FRAGMENT:
addDetailsFragment(0);
break;
}
}
}
And here is the method that add the DetailsFragment and ListFragment as needed
private void addListFragment(){
ClientDetailsFragment listFrag = new ClientDetailsFragment();
getSupportFragmentManager().beginTransaction()
.replace(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.addToBackStack("details")
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
}
private void addDetailsFragment(long companyId){
ClientDetailsFragment detailsFrag = ClientDetailsFragment.newInstance(companyId);
getSupportFragmentManager().beginTransaction()
.replace(R.id.container_client, detailsFrag, Constants.CLIENT_DETAILS_TAG)
.addToBackStack(null)
.commit();
currentFragment = CLIENT_DETAILS_FRAGMENT;
}
This works as expected except that when I click the back button from the Details Fragment, instead of taking me back to the List Fragment, it actually finishes the Activity. It goes back to the List Fragment for a split second and then finishes the host Activity and goes back to the calling Activity. How can I stop this behavior, after going through a lot of onBackpress related question on SO here is my overide of the onBackPressed
#Override
public void onBackPressed() {
if (currentFragment == CLIENT_DETAILS_FRAGMENT){
getSupportFragmentManager().popBackStackImmediate();
}else {
super.onBackPressed();
}
}
Thanks
Activity onBackPressed() should be:
For android.support.v4.app.Fragment
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 1)
getSupportFragmentManager().popBackStack();
else
finish();
}
For android.app.Fragment
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 1)
getFragmentManager().popBackStack();
else
finish();
}
I usually check whether the current fragment instance belongs to the fragment that invoked onBackPressed(). This code is untested; it's just to give you an idea on how to proceed. I hope you are not calling this.finish() on this Activity.
#Override
public void onBackPressed() {
Fragment fragment = getSuportFragmentManager().findFragmentByTag(Constants.CLIENT_DETAILS_TAG);
if (fragment instanceof ClientDetailsFragment) {
getSupportFragmentManager().popBackStackImmediate();
}
else {
super.onBackPressed();
}
}
Let me know if that helps.
Good Lord, I was chasing the wrong shadow for two days. I was listening, handling and overriding the wrong event.
This SO question saved me Why is onBackPressed() not being called?
And the gist is "onBackPressed() is invoked when user clicks on a hardware back button (or on the 'up' button in the navigation bar), not the button in the action bar. For this one you need to override onOptionsItemSelected() method. Example:"
I was catching this event the fragment and calling getActivity.onBackpressed. When I stopped this, it became obvious to me that the onBackPressed is not being called. Here is my solution, may not be optimal but it works
if (item.getItemId() == android.R.id.home){
if (currentFragment == CLIENT_DETAILS_FRAGMENT){
getSupportFragmentManager().popBackStackImmediate();
currentFragment = CLIENT_LIST_FRAGMENT;
return true;
}
}
if (currentFragment == 0) {
ClientListFragment listFrag = new ClientListFragment();
getSupportFragmentManager().beginTransaction()
.add(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
}
while changing this add to addToBackStack()
and,
change onBackPressed() like,
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 1) {
MainActivity.this.finish();
}
else {
getFragmentManager().popBackStack();
}
}
Hope, this will work.