So I have my navigation drawer with 5 different options. They all open a new fragment that I have created. The first one is Home, and I am trying to find a way to bring it back to the first screen that shows up under the navigation drawer. It has the id of "container", in the main_activity.xml. I do not want to use and intent to call the entire class again to load up. Also I do not want to be able to use the back button from another intent. I am confused on how to make this happen.
#Override
public void onNavigationDrawerItemSelected(int position) {
FragmentHowItWorks fragmentHow;
FragmentSettings fragmentSettings;
FragmentTransaction transaction = getFragmentManager().beginTransaction();
switch(position){
case 0:
// should I call the layout?
// this is the "Home" option
break;
case 1:
fragmentHow = new FragmentHowItWorks();
transaction.replace(R.id.container, fragmentHow);
transaction.addToBackStack(null);
transaction.commit();
break;
case 2:
fragmentSettings = new FragmentSettings();
transaction.replace(R.id.container, fragmentSettings);
transaction.addToBackStack(null);
transaction.commit();
break
case 3:
fragment = new FragmentHowItWorks();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 4:
fragment = new FragmentHowItWorks();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
break;
}
}
Use methods add,hide and show,
Step1 Prepare all your fragments
Fragment fragment1 = new FragmentOne();
Fragment fragment2 = new FragmentTwo();
Fragment fragment3 = new FragmentThree();
Fragment mCurrentFragment = null;
Step2 Show/hide your fragments
#Override
public void onNavigationDrawerItemSelected(int position) {
Fragment fragment;
switch (position) {
case 1:
fragment = fragment1;
break;
case 2:
fragment = fragment2;
break;
case 3:
fragment = fragment3;
break;
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if(mCurrentFragment == null) {
ft.add(R.id.container, fragment).commit();
mCurrentFragment = fragment;
} else if(fragment.isAdded()) {
ft.hide(mCurrentFragment).show(fragment).commit();
} else {
ft.hide(mCurrentFragment).add(R.id.container, fragment).commit();
}
mCurrentFragment = fragment;
}
You can do this ,
You can get the name of current fragment which is in the container . This will return name including the package + fragment name
String name = getFragmentManager().findFragmentById(container id ).getClass().getName();
When you click on the home index of drawer, check weather the current name id equal to the home.
If it is home, you don't need to perform any action.
I know that this was asked and answered long time ago but, I would like to show my approach on this problem, maybe it will help anyone else:
I added a Fragment Name over each Fragment that I use like:
public class MainFragment extends BaseFragment {
public static final String FRAGMENT_TAG = "main";
// ... all your fragment
}
And on the Drawer Layout:
public void methodThatSetsTheUi() {
mDrawerView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
getFragmentManager().findFragmentByTag("main");
String tag = getFragmentTag(position);
replaceFragment(getOrCreateFragment(tag), tag);
mDrawerLayout.closeDrawer(mDrawerView);
}
});
}
#NonNull
private String getFragmentTag(int position) {
String tag;
switch (position) {
case MAIN_FRAGMENT_DRAWER_POSITION:
tag = MainFragment.FRAGMENT_TAG;
break;
case FAVORITE_FRAGMENT_DRAWER_POSITION:
tag = FavoriteFragment.FRAGMENT_TAG;
break;
default:
throw new AssertionError("That selection is wrong");
}
return tag;
}
private BaseFragment getOrCreateFragment(String fragmentName) {
BaseFragment fragment = (BaseFragment) getFragmentManager().findFragmentByTag(fragmentName);
if(fragment == null) {
fragment = FragmentFactory.createFragment(fragmentName);
}
return fragment;
}
and well, the FragmentFactory is just a simple Factory:
public final class FragmentFactory {
public static BaseFragment createFragment(String fragmentName) {
switch(fragmentName) {
case MainFragment.FRAGMENT_TAG:
return MainFragment.newInstance();
case FavoriteFragment.FRAGMENT_TAG:
return FavoriteFragment.newInstance();
// ... all fragments here.
default:
return null;
}
}
Hope to help someone.
Related
My app has a navigation drawer with three items linking to three fragments A, B and C
when I click on the back button from any of the Fragments, the app exits.I solved this by declaring these constants in my base activity:
public static boolean IS_FRAGMENT_A = false;
public static boolean IS_FRAGMENT_B = false;
public static boolean IS_FRAGMENT C = false;
and then in the selectView method I did this:
private void displayView(int position) {
IS_FRAGMENT_A = false;
IS_FRAGMENT_B = false;
IS_FRAGMENT_C = false;
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new FragmentA();
IS_FRAGMENT_A = true;
break;
case 1:
fragment = new FragmentB();
IS_FRAGMENT_B = true;
break;
case 2:
fragment = new FragmentC();
IS_FRAGMENT_C = true;
break;
default:
break;
}
And in the overriden onBackPressed() method I did this
public void onBackPressed() {
if (IS_FRAGMENT_A) {
finish();
} else {
displayView(0);
}
}
This works fine when am navigating to these fragments from the navigation drawer.However, when I go to any of the fragments through an ActionBar button, the onBackPressed method does not work.
In Fragment A, I have an ActionBar button that takes me to Fragment B:
public boolean onOptionsItemSelected(MenuItem menuItem) {
int id = menuItem.getItemId();
switch (id) {
case R.id.action_new:
Fragment fragmentB = new FragmentB();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.frame_container, fragmentB);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
return true;
default:
return super.onOptionsItemSelected(menuItem);
}
}
When I press the back button from FragmentB after navigating to it via this method the app exits, unlike when I navigate to it through the navigation drawer.
I have tried adding this to the onCreate() method of FragmentB with no luck:
BaseActivity.IS_FRAGMENT_B = true;
My question is, how do I make the back button work in all fragments irrespective of how I got there?
I have three fragments and a Navigation drawer in my app viz, HomeFragment,DetailFragment and CountryFragment. Now when Iam in HomeFragment(Default fragment), I check a condition, if it returns false, I want to redirect to the CountryFragment without replacing the fragment.
Initially, in the host activity Iam doing something like this:-
HomeActivity.
private Android.Support.V4.App.Fragment mCurrentFragment = new SupportFragment();
private Stack<Android.Support.V4.App.Fragment> mStackFragments;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView (Resource.Layout.homelayout);
Android.Support.V4.App.FragmentTransaction tx = SupportFragmentManager.BeginTransaction();
tx.Add(Resource.Id.main, homeFragment);
tx.Add(Resource.Id.main, countryFragment);
tx.Hide(countryFragment);
tx.Add(Resource.Id.main, detailFragment);
tx.Hide(detailFragment);
CurrentFragment = homeFragment;
tx.Commit();
}
void MenuListView_ItemClick (object sender, AdapterView.ItemClickEventArgs e)
{
Android.Support.V4.App.Fragment fragment = null;
switch (e.Id)
{
case 0:
ShowFragment(homeFragment);
break;
case 1:
ShowFragment(countryFragment);
break;
case 2:
ShowFragment(detailFragment);
break;
}
}
public void ShowFragment(SupportFragment fragment)
{
if (fragment.IsVisible)
{
return;
}
var trans = SupportFragmentManager.BeginTransaction();
fragment.View.BringToFront();
mCurrentFragment.View.BringToFront();
trans.Hide(mCurrentFragment);
trans.Show(fragment);
trans.AddToBackStack(null);
mStackFragments.Push(mCurrentFragment);
trans.Commit();
mCurrentFragment = fragment;
}
Next in HomeFragment Iam doing something like :-
public void BtnCompleteSubmit_Click(object sender, EventArgs e)
{
dlgAlert.Dismiss();
CountryFragment countryFrag = new CountryFragment ();
// Create new fragment and transaction
var myActivity = (HomeActivity)this.Activity;
myActivity.ShowFragment(countryFrag );
}
This does go to the ShowFragment() of the HomeActivity, but the view for the fragment is null even thought the View was created initially while the NavigationDrawer was created. How do I solve this? any help is appreciated.
What you can do is create all fragment with a String Tag name associated.
Then add it your fragment transcation using fragment manager.
After if you want to shift between the fragments, then write an if else statement and find the fragment by tag method.
if (mFragManager.findFragmentByTag("FRAG_HOME") != null)
showFragment(mFragManager.findFragmentByTag("FRAG_HOME"));
else
showFragment(new homeFragment(), "FRAG_HOME");
In you show Fragment method:
public void ShowFragment(Fragment fragment, String tag)
{
mFragTransaction= mFragManager.BeginTransaction();
if (fragment.isAdded())
mFragTransaction.show(fragment);
else
mFragTransaction.add(ResId, fragment, tag).setBreadCrumbShortTitle(tag);
mFragTransaction.addToBackStack(tag);
mFragTransaction.commit();
}
I have built an Android application that uses tabs to navigate. I am using fragments for the majority of the application, however I need to display one activity. How do i display an activity in case 2. Below is the code i have at the moment, i know it returns a fragment but how do i enable the use of both?
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
System.out.println("current position = " + position);
Fragment fragment = null;
switch(position){
case 0:
return new diaryFragment();
case 1:
return new newEntryFragment();
case 2:
return new Calendarnew();
}
return null;
}
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new diaryFragment();
break;
case 1:
fragment = new newEntryFragment();
case 2:
fragment = new Calendarnew();
break;
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment).commit();
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
Hi I dont actually get what you are up to but try reading this, maybe it could somehow solve your issue. https://stackoverflow.com/a/2958586/4470313
My App starts with a AddressFragment. From the NavigationDrawer I start (amongst others) a new AddressFragment with:
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new AddressFragment())
.addToBackStack(null)
.commit();
But I would rather just go back the first instance. How could I do that?
Or more general, how can I find out, whether an instance of a fragment already exists and then start that, if yes, otherwise create one?
When creating the fragment set a tag for it, then later you can find it through the fragment manager and replace/create accordingly.
FragmentManager fManager = getFragmentManager();
FragmentTransaction fTransaction = fManager.beginTransaction();
Fragment fragment = fManager.findFragmentByTag("uniqueTag");
// If fragment doesn't exist yet, create one
if (fragment == null) {
fTransaction.add(R.id.fragment_list, new ListFrag(), "uniqueTag");
}
else { // re-use the old fragment
fTransaction.replace(R.id.fragment_list, fragment, "uniqueTag");
}
Step one:
Optimize current code to allow a Fragment to have his own "TAG"
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new AddressFragment())
.addToBackStack(**AddressFragment.class.getName()**)
.commit();
Step two:
Somewhere in your application flow you will need to determine if a fragment exists:
public static boolean isFragmentInBackstack(final FragmentManager fragmentManager, final String fragmentTagName) {
for (int entry = 0; entry < fragmentManager.getBackStackEntryCount(); entry++) {
if (fragmentTagName.equals(fragmentManager.getBackStackEntryAt(entry).getName())) {
return true;
}
}
return false;
}
Step three:
perform fragment action
if (exists) {
// Fragment exists, go back to that fragment
//// you can also use POP_BACK_STACK_INCLUSIVE flag, depending on flow
mFragmentManager.popBackStackImmediate(AddressFragment.class.getName(), 0);
} else {
// Fragment doesn't exist
// STEP 1 + additional backstack management
}
This is tested answer, Hope this will help you
First Make these field globally in MainActivity
private static final int TIME_INTERVAL = 2000;
private long mBackPressed;
private FragmentManager fm;
private FragmentTransaction ft;
private DrawerLayout drawer;
Now in onNavigationItemSelected() implement like that
#Override
public boolean onNavigationItemSelected(MenuItem item) {
Fragment fragment = null;
Class fragmentClass = null;
switch (item.getItemId()) {
case R.id.nav_home:
fragmentClass = Fragment.class;//this is MainAvctivty extends AppCompatActivity
break;
case R.id.nav_f1:
fragmentClass = FragmentOne.class;
break;
case R.id.nav_f2:
fragmentClass = FragmentTwo.class;
break;
case R.id.nav_f3:
fragmentClass = FragmentThree.class;
break;
case R.id.nav_f4:
fragmentClass = FragmentFour.class;
break;
case R.id.nav_f5:
fragmentClass = FragmentFive.class;
break;
default:
fragmentClass = Fragment.class;
}
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {e.printStackTrace();}
//Insert the fragment by replacing any existing fragment
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
ft.replace(R.id.frame_container, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
item.setChecked(true);
setTitle(item.getTitle());
drawer.closeDrawers();
return true;
}
Now handle onbackpressed like below
#Override
public void onBackPressed() {
if (drawer != null) {
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
ft.commit();
} else if (mBackPressed + TIME_INTERVAL > System.currentTimeMillis()) {
super.onBackPressed();
} else {
Toast.makeText(this,"Press again to exit the app",Toast.LENGTH_SHORT).show();
}
mBackPressed = System.currentTimeMillis();
}
}
First time you create the fragment with a tag.
When you want to replace it try to get the fragment with tag and if it return null you create a new one
I basically have a layout divided into two halves. On my left i have buttons that trigger the various fragments that are displayed in the layout on my right.
When i click on each button the respective fragment is loaded in the fragment display area. Some of the fragments for example Fragment A and Fragment D display complex data by querying a database or getting data from the internet etc. As long as the app is running this data will not change once it is loaded. My question is can i just revert the fragment to the previous state and display it. To be more clear -> i click Fragment A button, in the Fragment A class all the calculations are done and displayed, then i click Fragment B and fragment B is displayed and then C. Now when i click back on Fragment A button i just want it to load back the data, not redo calculation/connections/db queries.
Code being used :
public void onClick(View v) {
switch (position) {
case 0:
newContent = new FragmentA();
break;
case 1:
newContent = new FragmentB();
break;
case 2:
newContent = new FragmentC();
break;
case 3:
newContent = new FragmentD();
break;
case 4:
newContent = new FragmentE();
break;
default: break;
}
if (newContent != null){
mContent = newContent;
switchFragment(newContent);
}
}
public void switchFragment(Fragment fragment) {
mContent = fragment;
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.replacelayout, fragment)
.commit();
}
Fragment Code example
public class FragmentA extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragmenta, container, false);
}
#Override
public void onActivityCreated (Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
RUN ASYNTASKS TO CONNECT/QUERYDB AND DIPLAY THE DATA
}
}
Don't know how to go about it - using backStack ?? onResume() ?? because i am not sure what function is invoked when the .replace is invoked.
Thanks in Advance
Instead of using fragment.replace you can use fragment.show and fragment.hide fragmentByTagName. This will keep they're states in memory. It might look something like this.
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
//find the fragment by View or Tag
MyFrag myFrag = (MyFrag)fragmentManager.findFragmentByTag(TAG);
fragmentTransaction.hide(myOldFrag);
fragmentTransaction.show(myNewFrag);
fragmentTransaction.commit();
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Fragment newContent = null;
getSupportFragmentManager()
.beginTransaction()
.hide(mContent)
.commit();
switch (position) {
case 0:
getSupportFragmentManager()
.beginTransaction()
.show(home)
.commit();
mContent = home;
getSlidingMenu().showContent();
break;
case 1:
if(ifdownexsists == true){
getSupportFragmentManager()
.beginTransaction()
.show(download)
.commit();
mContent = download;
getSlidingMenu().showContent();}
else
{ download = new DownloadFile();
getSupportFragmentManager()
.beginTransaction()
.add(R.id.replacelayout, download)
.commit();
mContent = download;
ifdownexsists = true;
getSlidingMenu().showContent();
}
break;
case 2:
if(ifexsists == true){
getSupportFragmentManager()
.beginTransaction()
.show(oldCheckValue)
.commit();
mContent = oldCheckValue;
getSlidingMenu().showContent();}
else
{ oldCheckValue = new CheckValues();
getSupportFragmentManager()
.beginTransaction()
.add(R.id.replacelayout, oldCheckValue)
.commit();
mContent = oldCheckValue;
ifexsists = true;
getSlidingMenu().showContent();
}
break;
Works like a charm ... even keeps the progress of the progressbars in the background and shows them correctly when the fragment becomes visible again