Develop Reference

Go back to fragment from activity

I have the following Activity code:-
public class legislator_info extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_legislator_info);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Legislator Info");
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Intent i = getIntent();
String bioguide = i.getExtras().getString("Person");
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// click on 'up' button in the action bar, handle it here
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
So basically I have a fragment which has a list view displayed in it. On click of a list Item I start this activity and I want to go back to the previous fragment on the back button click. I tried the above code but I am not able to travel back. Am pretty new at this any help is appreciated.
I have added my fragment in the following way:-
android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();
LegislatorFragment lf = new LegislatorFragment();
ft.replace(R.id.fragment_container,lf);
ft.addToBackStack(null);
ft.commit();

I am still not clear what you want to achieve but you can try this
#Override
public void onBackPressed() {
super.onBackPressed();
finish();
}
EDIT:
case android.R.id.home:
//call onBackPressed here
onBackPressed();
return true;

You have to override onOptionsItemSelected because you are trying with Action bar's back button.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
Then override BackPressed -
#Override
public void onBackPressed()
{
FragmentManager fm = getSupportFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
}
else {
super.onBackPressed();
}
}

Android home button with drawer navigation stops to work with rotation screen

I have a main activity with navigation drawer and a button to load fragment.
When the main ativity is launched I load the MainFragment.
In this moment all works well. The hamburger icon is showing and my Main fragment was loaded.
Next, I click a button and load a secondFragment. After I load the second fragment, I can use the backbutton and homebutton to come back to main activity without problems.
When I am with second fragment loaded and I make a rotation screen, the back button continues to work well, but the home button disappears and hamburger icon appears.
What am i doing wrong?
public class MainActivity extends AppCompatActivity {
private ActionBarDrawerToggle actionBarDrawerToggle;
private DrawerLayout drawerLayout;
private Toolbar toolbar;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String mSubTitle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
initNavigationDrawer();
if (savedInstanceState != null) {
return;
}
MainActivityFragment mainFragment = new MainActivityFragment();
firstFragment.setArguments(getIntent().getExtras());
// Add the fragment to the 'fragment_container' FrameLayout
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
//transaction.replace(R.id.fragment_container, firstFragment);
transaction.replace(R.id.fragment_container, mainFragment, "princ");
transaction.commit();
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Only handle with DrawerToggle if the drawer indicator is enabled.
if (actionBarDrawerToggle.isDrawerIndicatorEnabled() &&
actionBarDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle your other action bar items...
return super.onOptionsItemSelected(item);
}
}
public Fragment getCurrentFragment(){
FragmentManager frgmgr = getSupportFragmentManager();
return frgmgr.findFragmentById(R.id.fragment_container);
}
#Override
public void onBackPressed() {
if (drawerLayout != null) {
if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
drawerLayout.closeDrawer(GravityCompat.START);
return;
}
}
if ((getCurrentFragment() instanceof MainFragment)) {
finish();
} else if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else super.onBackPressed();
}
public void initNavigationDrawer() {
NavigationView navigationView = (NavigationView) findViewById(R.id.navigation_view);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
FragmentManager frgmgr = getSupportFragmentManager();
FragmentTransaction transaction = frgmgr.beginTransaction();
Fragment cur_frag;
// Handle navigation view item clicks here.
int id = menuItem.getItemId();
switch (id) {
case R.id.home:
cur_frag = frgmgr.findFragmentById(R.id.fragment_container);
if (!(cur_frag instanceof MainActivityFragment)) {
MainActivityFragment frag = new MainActivityFragment();
transaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_left);
transaction.replace(R.id.fragment_container, frag);
transaction.commit();
break;
}
drawerLayout.closeDrawers();
break;
case R.id.logout_drw:
finish();
}
drawerLayout.closeDrawer(GravityCompat.START);
return true;
}
});
View header = navigationView.getHeaderView(0);
TextView tv_email = (TextView) header.findViewById(R.id.tv_email);
tv_email.setText("Agendamento");
drawerLayout = (DrawerLayout) findViewById(R.id.drawer);
mTitle = mDrawerTitle = getTitle();
actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) {
#Override
public void onDrawerClosed(View v) {
super.onDrawerClosed(v);
}
#Override
public void onDrawerOpened(View v) {
super.onDrawerOpened(v);
}
};
drawerLayout.addDrawerListener(actionBarDrawerToggle);
actionBarDrawerToggle.syncState();
if (toolbar != null) {
getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
int i=getSupportFragmentManager().getBackStackEntryCount();
if ((i > 0) || (!(getCurrentFragment() instanceof MainActivityFragment))) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true); // show back button
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onBackPressed();
}
});
} else {
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
actionBarDrawerToggle.syncState();
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
drawerLayout.openDrawer(GravityCompat.START);
}
});
}
}
});
}
}
}
Main Fragment:
public class MainFragment extends Fragment {
public MainFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment_main, container, false);
Button butCons= (Button) view.findViewById(R.id.butcons);
butCons.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
SecundaryFrag frag = new SecundaryFragFrag();
// Add the fragment to the 'fragment_container' FrameLayout
FragmentTransaction transaction=getFragmentManager().beginTransaction();
transaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_left);
transaction.replace(R.id.fragment_container, frag);
transaction.addToBackStack(null);
transaction.commit();
}
});
return view;
}
}
Secondary Fragment:
public class SecundaryFrag extends Fragment{
public SecundaryFrag() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment_consulta_ag, container, false);
return view;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
((MainActivity)getActivity()).onBackPressed();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
After Rotation:
Main activty with main fragment:
Before Rotation:

I believe it is related to the fact that the view is recreated after the orientation change. I would take a closer look to the onCreate() from the MainActivity in particular when the
if (savedInstanceState != null) {
return;
}
is triggered.
One option is to retain the fragments and restoring them onCreate. Also you could turn off the recreation by catching the orientation and handle it yourself in the application, you can see here both options explained developer.android.com/guide/topics/resources/

Why not works ClickListeners for Toolbar?

I use MaterialDrawer and code MainActivity is:
public class MainActivity extends AppCompatActivity implements KitchenFragment.CallbackOne {
public static final String TAG = "myLogTag";
private Toolbar mToolbar;
private Drawer drawer;
private FragmentManager fm;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mToolbar = (Toolbar) findViewById(R.id.toolbar);
mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d(TAG, "CLICK NOCL");
}
});
setSupportActionBar(mToolbar);
// getSupportActionBar().setDisplayHomeAsUpEnabled(false);
fm = getFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.content_frame);
if (fragment == null) {
fragment = MenuFragment.newInstance();
fm.beginTransaction()
.add(R.id.content_frame, fragment)
.commit();
}
drawer = new DrawerBuilder()
.withActivity(this)
.withToolbar(mToolbar)
.withActionBarDrawerToggle(true)
.withHeader(R.layout.drawer_header)
.addDrawerItems(
new PrimaryDrawerItem().withName(R.string.menu).withIdentifier(1),
new PrimaryDrawerItem().withName(R.string.kitchen_title).withIdentifier(2),
new PrimaryDrawerItem().withName(R.string.information_title).withEnabled(false)
).withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() {
#Override
public boolean onItemClick(View view, int position, IDrawerItem drawerItem) {
Log.d(TAG, "position clicked: " + position);
Fragment fragment = MenuFragment.newInstance();
switch (position) {
case 1:
fragment = MenuFragment.newInstance();
break;
case 2:
fragment = KitchenFragment.newInstance();
break;
default:
fragment = new Fragment();
}
fm.beginTransaction().replace(R.id.content_frame, fragment).commit();
return false;
}
})
.withFireOnInitialOnClick(true)
.withSavedInstance(savedInstanceState)
.withOnDrawerNavigationListener(new Drawer.OnDrawerNavigationListener() {
#Override
public boolean onNavigationClickListener(View view) {
Log.d(TAG, "CLICK in DNL");
if (!drawer.getActionBarDrawerToggle().isDrawerIndicatorEnabled()) {
onBackPressed();
return true;
} else
return false;
}
})
.build();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
Log.d(TAG, "CLICK OIS");
switch (item.getItemId()) {
case R.id.action_settings:
return true;
case android.R.id.home:
getFragmentManager().popBackStackImmediate();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
outState = drawer.saveInstanceState(outState);
super.onSaveInstanceState(outState);
}
#Override
public void onBackPressed() {
if (drawer.isDrawerOpen())
drawer.closeDrawer();
else if (getFragmentManager().getBackStackEntryCount() == 1) {
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
drawer.getActionBarDrawerToggle().syncState();
getFragmentManager().popBackStack();
} else if (getFragmentManager().getBackStackEntryCount() > 0)
getFragmentManager().popBackStack();
else
super.onBackPressed();
}
#Override
public void setFirstSelected() {
drawer.setSelection(1);
}
}
I'm trying to trace a Click in mToolbar.setNavigationOnClickListener
and withOnDrawerNavigationListener and onOptionsItemSelected.
None of the listeners not reacted for clicking.
How you see i use Activity that launches Fragment (1), which in turn lets Fragment (2 and 3). In 2 and 3 Fragment in OnCreate i use ((AppCompatActivity)getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true); , and I need to by pressing the back button (in toolbar), returning the previous fragment, and not open Drawer

The MaterialDrawer already handles all the listeners for you. If you need to do an action after the drawer opens or closes you can provide the listener via the DrawerBuilder
For the icon you have this listener:
OnDrawerNavigationListener
https://github.com/mikepenz/MaterialDrawer/blob/develop/library/src/main/java/com/mikepenz/materialdrawer/DrawerBuilder.java#L1158
For drawer close / open this listener:
OnDrawerListener
https://github.com/mikepenz/MaterialDrawer/blob/develop/library/src/main/java/com/mikepenz/materialdrawer/DrawerBuilder.java#L1116

I suggest you to create new Activity using android studio wizard. File->New->Activity->Navigation Drawer Activity.
In that case ActionBarDrawerToaggle is used
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
This toggle contains click listener which handle open/close drawer functionality for you.
Also you can that item clicks implemented through OnNavigationItemSelectedListener.onNavigationItemSelected(MenuItem item)

MainActivity to fragment and back to MainActivity on pressing back button

I have a Mainactivity which contains a Layout which is parent of 4 sub layout. on clicking on sub layout i am going to a new fragment replacing main layout. But i cant go back to MainActivity after pressing Back button
MainActivity.java
public class MainActivity extends AppCompatActivity {
RelativeLayout aboutUs;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
aboutUs = (RelativeLayout) findViewById(R.id.aboutUs);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
//click methods goes here
public void clickAboutUs(View view){
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
FragmentAboutUs fragmentAboutUs = new FragmentAboutUs();
fragmentTransaction.replace(R.id.fragment_container,fragmentAboutUs);
fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
FragmentAboutUs.java
public class FragmentAboutUs extends Fragment
{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.about_us, container,false);
return view;
}
}
How to go back to main page again after pressing back button from fragment.

Try Like this
public boolean popFragment() {
boolean isPop = false;
Fragment currentFragment = getSupportFragmentManager()
.findFragmentById(R.id.flContent);
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
isPop = true;
getSupportFragmentManager().popBackStackImmediate();
}
return isPop;
}
#Override
public void onBackPressed() {
if (!popFragment()) {
finish();
}
}
public void replaceFragment(Fragment fragment, boolean addToBackStack) {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
if (addToBackStack) {
transaction.addToBackStack(null);
} else {
getSupportFragmentManager().popBackStack(null,
FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
transaction.replace(R.id.fragment_container, fragment);
transaction.commit();
getSupportFragmentManager().executePendingTransactions();
}
add above method is in your parent Activity
And Use like
FragmentAboutUs fragmentAboutUs = new FragmentAboutUs();
replaceFragment(fragmentAboutUs , true);

If you have one Activity and four fragments then set onBackPressed() as below in your MainActivity.
#Override
public void onBackPressed()
{
super.onBackPressed();
finish();
}
And in fragments:
#Override
public void onResume() {
super.onResume();
new PlayListFragment();
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
if(getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
}
return true;
}
return false;
}
});
}

You can Override the onBackPressed of MainActivity
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 1) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}

Here is how it can be done in Xamarin:
Load fragment (I wrote helper method for that, but it's not necessary):
public void LoadFragment(Activity activity, Fragment fragment)
{
var backStateName = fragment.GetType().Name;
var fm = activity.FragmentManager;
var ft = fm.BeginTransaction();
ft.Replace(Resource.Id.mainContainer, fragment);
ft.AddToBackStack(backStateName);
ft.Commit();
}
Back button (in MainActivity):
public override void OnBackPressed()
{
if (isNavDrawerOpen()) drawerLayout.CloseDrawers();
else
{
var backStackEntryCount = FragmentManager.BackStackEntryCount;
if (backStackEntryCount == 1) Finish();
else if (backStackEntryCount > 1) FragmentManager.PopBackStack();
else base.OnBackPressed();
}
}
isNavDrawerOpen method:
bool isNavDrawerOpen()
{
return drawerLayout != null && drawerLayout.IsDrawerOpen(Android.Support.V4.View.GravityCompat.Start);
}

How to get click event of DrawerArrowDrawable

I am using DrawerArrowDrawable to animate the hamburger icon during the opening and closing of Navigation drawer. Following is the code snippet I used for that:
DrawerArrowDrawable drawerArrow = new DrawerArrowDrawable(this);
toolbar.setNavigationIcon(drawerArrow)
mDrawerToggle.syncState();
Now when I open a fragment I use actionBar.setHomeAsUpIndicator(R.drawable.back_icon); & actionBar.setDisplayHomeAsUpEnabled(true); in that very fragment, to change the navigation icon as a back icon. The icon changes but the functionality of that button stays same i.e., it opens the navigation drawer, but I want to go back to the previous fragment (by using popBackStack).
I tried to override onOptionsItemSelected :
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
FragmentManager fm = getSupportFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
}
break;
}
}
But the control never reaches in the above block when I press the navigation icon.
If I get to know that How to intercept the click event of DrawerArrowDrawable? I would be able to run popBackStack and do what I want to do.

toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentManager fm = getSupportFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
}
}
});

Add this listener inside the Navigation Drawer Activity:
private FragmentManager.OnBackStackChangedListener mOnBackStackChangedListener = new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
setActionBarArrowDependingOnFragmentsBackStack();
}
};
Then create this method:
public void setActionBarArrowDependingOnFragmentsBackStack() {
int backStackEntryCount = getFragmentManager().getBackStackEntryCount();
mDrawerToggle.setDrawerIndicatorEnabled(backStackEntryCount == 0);
}
Now override these methods:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (mDrawerToggle.isDrawerIndicatorEnabled() && mDrawerToggle.onOptionsItemSelected(item)) {
return true;
} else if (item.getItemId() == android.R.id.home && getFragmentManager().popBackStackImmediate()) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
return super.onCreateOptionsMenu(menu);
}
#Override
public void onDestroy() {
super.onDestroy();
getFragmentManager().removeOnBackStackChangedListener(mOnBackStackChangedListener);
}
Finally add this line inside your onCreate() method:
getFragmentManager().addOnBackStackChangedListener(mOnBackStackChangedListener);