I am developing an android app using fragments. I have five fragments. Those are A,B,C,D,E . My first fragment A is the main fragment. First I traverse from A to B then from B to C. In C when I press back button I want it to go back to A. I have used the below code for calling B fragment from A. This same method is used for calling another fragments.
FragmentB fragment = new FragmentB();
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction().addToBackStack("tag");
transaction.replace(R.id.content_frame, fragment);
transaction.commit();
The back button code in the activity is as following
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
How to solve this issue please help me.
You can try this:
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} FragmentManager fragmentManager = getSupportFragmentManager();
int backCount = fragmentManager.getBackStackEntryCount();
System.out.println("back count " + backCount);
if(backCount==0)
{
actionBar.setTitle("Home");
//Here you can show alert dialog for exit the app?
}
/* else if(backCount==1)
{
}*/
else if(backCount==1)
{
fragmentManager.popBackStack();
// setTitle("Home");
navigationView.getMenu().getItem(0).setChecked(true);
actionBar.setTitle("Home");
}
else if(backCount>1)
{
for(int i=fragmentManager.getBackStackEntryCount();i>=1;i--)
{
fragmentManager.popBackStack();
System.out.println("back count loop" + fragmentManager.getBackStackEntryCount());
}
actionBar.setTitle("Home");
}
}
Try this:
#Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawers();
return;
}
// This code loads home fragment when back key is pressed
// when user is in other fragment than home
if (shouldLoadHomeFragOnBackPress) {
// checking if user is on other navigation menu
// rather than home
if (navItemIndex != 0) {
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
loadHomeFragment();
return;
}
}
super.onBackPressed();
}
Refer this reference : https://www.androidhive.info/2013/11/android-sliding-menu-using-navigation-drawer/
Related
I have two fragments namely FoodFragment and WishlistFragment these two are opened when i press their respective item clicks through the NavigationView
The problem I'm facing is when I press on the navigation items the fragments corresponding to them opens and everything works fine but when i press the back button, the MainActivity's onBackPressed() method is called and it only works for the first condition on the fragment that I've written.
Here's my code:
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
int id = item.getItemId();
mFragmentTransaction = getSupportFragmentManager().beginTransaction();
if (id == R.id.food) {
if(newFragment == null) {
newFragment = FoodFragment.newInstance("food", "fragment");
mFragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
mFragmentTransaction.replace(R.id.appBar, newFragment, "FoodFragment").addToBackStack("FoodFragment").commit();
}
}else if(id == R.id.wishlist){
if(wishFragment == null){
wishFragment = WishlistFragment.newInstance("wish", "fragment");
mFragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
mFragmentTransaction.replace(R.id.appBar, wishFragment, "WishFragment").addToBackStack("WishFragment").commit();
}
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
Here's the onBackPressed() method:
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
try {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if(getSupportFragmentManager().findFragmentByTag("WishFragment").isVisible()){
getSupportFragmentManager().popBackStack();
wishFragment = null;
}else if (getSupportFragmentManager().findFragmentByTag("FoodFragment").isVisible()) {
getSupportFragmentManager().popBackStack();
newFragment = null;
}else {
super.onBackPressed();
}
}catch (NullPointerException npe){
super.onBackPressed();
}
}
I've added tags to each fragment as you can see in the code and handling them through the onBackPressed() method. Here, when I open the WishFragment and press back button everything is cleared and so i can open the WishFragment again by pressing the Navigation Item corresponding to it. But, this seems to be getting wrong in case of FoodFragment when I open the fragment and press back button, the condition corresponding to it is not executed and So, I'm unable to open the FoodFragment again.
But, if I change the ordering of conditions in onBackPressed() like this:
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
try {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
}else if (getSupportFragmentManager().findFragmentByTag("FoodFragment").isVisible()) {
getSupportFragmentManager().popBackStack();
newFragment = null;
} else if(getSupportFragmentManager().findFragmentByTag("WishFragment").isVisible()){
getSupportFragmentManager().popBackStack();
wishFragment = null;
}else {
super.onBackPressed();
}
}catch (NullPointerException npe){
super.onBackPressed();
}
}
It seems to work now with FoodFragment but not with WishFragment, as a result I was able to open the FoodFragment again but not the WishFragment. I've searched for this problem on many websites but, I cannot get the right answer.
I've resolved it by adding view.setOnKeyListener(//calling the MainActivity by KeyEvents) for the fragment but, this doesn't seem to be a good way to do things as it reloads my entire MainActivity again.
I don't know where I'm doing wrong. Please suggest me a better way to do this.
Thank you.
When the WishFragment is open and you press the back button
getSupportFragmentManager().findFragmentByTag("FoodFragment").isVisible()
This throws a NullPointerException.
So it will always do super.onBackPressed()since you are catching all the NullPointerException
To solve this change your if else statement to
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (getSupportFragmentManager().findFragmentByTag("FoodFragment") != null && getSupportFragmentManager().findFragmentByTag("FoodFragment").isVisible()) {
getSupportFragmentManager().popBackStack();
newFragment = null;
} else if(getSupportFragmentManager().findFragmentByTag("WishFragment") != null && getSupportFragmentManager().findFragmentByTag("WishFragment").isVisible()){
getSupportFragmentManager().popBackStack();
wishFragment = null;
} else {
super.onBackPressed();
}
I am trying to close the fragment and wants to resume the main activity by using the addToBackStack in my fragment implimentation but it is not working. Back button is closing the application.
The fragment implimentation method that I am using is,
private void dispaySelectedScreen(int id) {
Fragment fragment = null;
switch (id) {
case R.id.facebook_login:
fragment = new FacebookLogin();
break;
case R.id.memes:
fragment = new Memes();
break;
case R.id.submit_image:
fragment = new SubmitImage();
break;
case R.id.discussion:
fragment = new Discussions();
break;
case R.id.invite:
fragment = new Invite();
break;
case R.id.connect_fb:
fragment = new FacebookConnect();
break;
case R.id.connect_twitter:
fragment = new TwitterConnect();
break;
case R.id.connect_instagram:
fragment = new InstaConnect();
break;
}
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_main, fragment);
ft.addToBackStack(null);
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
I have also declared one onBackPressed method for the drawer,
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
Please suggest..
fragment.addToBackStack(null) is enough to open the previous activity but if you want to handle some action on back pressed apart from removing the fragment then we override onBackPressed(), so this is my tested approach, kindly have a look:-
Below is my implementation:-
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_holder, new MyFragment(), "MY_FRAG")
.addToBackStack(null).commit();
}
#Override
public void onBackPressed() {
MyFragment fragment = (MyFragment) getSupportFragmentManager().findFragmentByTag("MY_FRAG");
if (fragment != null) {
if (fragment.isVisible()) {
//todo perform any action if you want when fragment is removed
}
} else {
super.onBackPressed();
}
}
I see you are using replace on transaction in that way your fragment will pop up from stack but it will reload i.e onCreateView() of that fragment will be called . Just replace
ft.replace(R.id.content_main, fragment);
to
ft.add(R.id.content_main, fragment);
For handling back button use following code .
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
//that means your stack is empty and you want to close activity
finish();
} else {
// pop the backstack here
getSupportFragmentManager().popBackStackImmediate();
}
}
}
Hi I have created fragments in app drawer and now when I am pressing the back button on a fragment, it is closing the application.
There is already one existing onKeyDown in the webView of Main activity.
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
if (myWebView.canGoBack()) {
myWebView.goBack();
} else {
finish();
}
return true;
}
}
return super.onKeyDown(keyCode, event);
For the onBackPressed method
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
Fragment Impementation method,
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_main, fragment);
ft.addToBackStack("close");
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
When you add a fragment to some container or inflate it using xml, it is not added to the backstack and so, when 'onBackPressed' occurs it throws the last activity from the backstack- which is the activity hosting the fragment and thus exiting the application.
I think this post:
Android: Fragments backStack
can help you, it explains how to add the fragment transaction to the backstack:
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(..............);
fragmentTransaction.addToBackStack("fragment transaction name, not required");
fragmentTransaction.commit();
You need to do this in following way
#Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
//that means your stack is empty and you want to close activity
finish();
} else {
// pop the backstack here
getSupportFragmentManager().popBackStackImmediate();
}
}
}
I think you dont add the fragments to the backstack.
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
//your code
fragmentTransaction.addToBackStack("your_tag");
When you evoke a fragment add it to stack like this
fragmentTransaction.addToBackStack("fragment");
and then in onBackPress pop it from stack like this
FragmentManager fm = getActivity()
.getSupportFragmentManager();
fm.popBackStack ("fragment", FragmentManager.POP_BACK_STACK_INCLUSIVE);
I'm new to Android development and developing an application using Android's default Navigation drawer layout.
I'm using fragment in the application.
I want to get back to previous fragment when back button is pressed on next fragment.
The onBackPress must implement following functions
Get back to previous fragment when on next fragment
Close drawer when navigation drawer is open
Exit app on double back press when in fragment1
This is what my code is in MainActivity
while creating new fragment
// replacing the fragment
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.commit();
}
onBackPress
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (getFragmentManager().getBackStackEntryCount() > 0) {
FragmentManager fm = getSupportFragmentManager();
fm.popBackStack();
} else {
super.onBackPressed();
}
}
But this is not working and on pressing back exits the application except when Navigation drawer is open it is closed.
You are not adding the fragment to the backstack. You just have to do
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
.replace(R.id.content_frame, fragment);
.addToBackStack(null);
.commit();
And since the Backstack is actually handled by the back button, you do not need to handle this scenario in onBackPressed(), so you can change it to just:
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
You have to add the Fragment in your FragmentTransaction to the backstack.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment).addtoBackStack(null).commit();
By giving the tag null they all get grouped by that tag. So if you need to close them all together you can do so or navigate to a certain one.
I also would not use replace(), because that one is incredibly buggy with the backstack.
Try to use remove() and then add().
You should add your fragment to the back stack and modify your code this way:
// this variable is needed to know how many times the back key has been pressed.
// It is incremented and reset accordingly to the logic you described
int mBackPressCount = 0;
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if (getFragmentManager().getBackStackEntryCount() == 0) {
// if there are no fragments in your back stack check the mBackPressCount
if (mBackPressCount++ > 0) {
// if you pressed back for the second time this line will terminate the activity
super.onBackPressed();
}
} else {
// this line will pop the fragment from the back stack,
// no need to pop it manually
super.onBackPressed();
}
}
}
Add the fragment to the back stack:
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(null);
ft.commit();
// when you add a fragment you should reset the back press count
mBackPressCount = 0;
}
Reset mBackPressCount when open and close the drawer. If you have pressed the back key once and you open the drawer the counter has to be set to 0 again.
DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerLayout.addDrawerListener(new DrawerLayout.DrawerListener() {
#Override
public void onDrawerSlide(View drawerView, float slideOffset) {
}
#Override
public void onDrawerOpened(View drawerView) {
mBackPressCount = 0;
}
#Override
public void onDrawerClosed(View drawerView) {
mBackPressCount = 0;
}
#Override
public void onDrawerStateChanged(int newState) {
}
});
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.