Develop Reference

Back Button in ActionBar of App

Generally switching from one activity to another activity hamburger icon is replaced with back arrow. I want to control the functionality of that arrow. I have seen many contents here but most of them were related to hardware's back button. How can I control that?
I am trying the functionality in case of fragments. Also I have Navigation drawer attached with the hamburger icon.
I tried this-
if(id == android.R.id.home){
getSupportFragmentManager().beginTransaction().replace(R.id.main_container, new AmbulanceMap()).commit();
getSupportActionBar().setTitle("Book A Ride");
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
}
but doesnt work as I hoped.
I want my back button to change the fragmentto previous fragment.

I had the same problem once. Just like you, things like checking if Android.R.id.home is clicked didn't work.
But I solved it using that:
Set navigation listener to toolbar:
toolbar.setToolbarNavigationClickListener(v -> onBackPressed());
If it should be within fragment:
Create an public method in activity.
In fragment's onAttach (or later) cast getActivity() to your activity and call method you was defined previously.
Example:
// YourActivity
public void setHomeListener(OnLickListener listener){
toolbar.setToolbarNavigationClickListener(listener);
}
//Fragment's onCreate
((YourActivity)getActivity()).setHomeListener(v -> onBackPressed());
//Fragment's onDestroy
((YourActivity)getActivity()).setHomeListener(null);
And, of course, set home us up enabled to show back arrow.
EDIT
if you don't use labmdas u should use:
(YourActivity)getActivity()).setHomeListener(new OnClickListener() {
#Override
public void onClick(View v) {
YourFragment.this.onBackPressed();
}
});

The back button of the ActionBar is a menuItem so you need to override onOptionsItemSelected like this:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()){
case android.R.id.home:
//Your back button logic here
break;
}
return true;
}
Also don´t forget to add getSupportActionBar().setDisplayHomeAsUpEnabled(true); after setting the Toolbar

Back navigation in title bar - fragment

There are many questions like this asked but everything I have tried seems to not work.
Essentially I have a main activity that calls different fragments depending on what the user clicks with the home fragment being default.
I would like to have a back button on the title bar, to go back to the previous fragment.
My fragment is called from the main activity like so:
Fragment fragment = null;
fragment = new nextFragment();
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.frame_container, fragment).addToBackStack(null);
fragmentTransaction.commit();
fragmentTransaction.addToBackStack(null);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
But since ActionBarActivity activity is deprecated I need to extend AppCompatActivity instead of FragmentActivity so I can use actionbar (I'm assuming this is what I need).
However then I am unable to switch to my fragment. So does anyone know how I could implement a back button in my fragment or how to use AppCompatActivity in this situation.
Thanks for any help.

Please try this if you extend AppCompatActivity:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Include these 2 lines ONLY if need to use Toolbar from layout xml as Action Bar
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//Add back navigation in the title bar
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
//
//Other works to be done in onCreate.....
//
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
//Title bar back press triggers onBackPressed()
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
//Both navigation bar back press and title bar back press will trigger this method
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0 ) {
getFragmentManager().popBackStack();
}
else {
super.onBackPressed();
}
}
}

To add Back Button in title bar, you must add the following code to your Fragment.
Toolbar toolbar = (Toolbar)view.findViewById(R.id.app_bar);
AppCompatActivity AppCompatActivity = (AppCompatActivity)getActivity();
AppCompatActivity.setSupportActionBar(toolbar);
AppCompatActivity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
return view;
}
Don't forget to extend your MainActivity to AppCompatActivity.
You must then use this Java code in my Fragment class to react to the user tapping the back/up icon in the action bar.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
getActivity().onBackPressed();
return true;
default:
return super.onOptionsItemSelected(item);
}
}

You've saved the last fragment used by calling
addToBacktack(null).commit()
So the next step forward to call it is by overriding onBackPressed() in the activity hosting the fragment.
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0 ){
getFragmentManager().popBackStack();
}
else {
super.onBackPressed();
}
}
So whenever you call the activity's onBackPressed() from the fragment, the fragment would go back to the last saved fragment.

Different toolbar behavior in different fragments... how?

I have an activity (MyActivity) with two fragments (MyFirstFragment and MySecondFragment). I want the screens correspondent to the two fragments to display the same exact toolbar: just the 'home' button ('🡠') and the top right corner menu, with only one item (let's call it Foo).
The only difference among them should be the behavior when clicking on Foo. (Just to make an example, when I'm on MyFirstFragment and I press Foo I want it to display a Toast, while whem I'm on MySecondFragment I want it to open an AlertDialog).
What do you think could be the best implementation for this?
Can I define the toolbar inside MainActivity.java but then set two different behaviours in each fragment java file? How?
I'll add some code, here's how I'm defining the toolbar inside my MyActivity.java for the moment:
#Override
protected void onCreate(Bundle savedInstanceState) {
// [...]
Toolbar tb = (Toolbar) findViewById(R.id.toolbar_my);
setSupportActionBar(tb);
if (getSupportActionBar() != null)
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
tb.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
onBackPressed(); //goes to the previous fragment
}
});
// [...]
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.foo:
// do something
return true;
default:
return false;
}
}

Yep, just define your Toolbar inside MyActivity.java and then in each fragment constructor set this flag to true. Then override onOptionsItemSelected(MenuItem item) with different behavior in each fragment.

How to up navigate from fragment activity?

Hi I am having trouble while going back to parent activity from fragment activity. I want back arrow at top left corner inside the action bar.
I am able to show it in action bar activity using this code
getSupportActionBar().setDisplayShowHomeEnabled(true);
But I am not able to do it in tabbed activity's fragment.
((AppCompatActivity)getActivity()).getSupportActionBar().setDisplayShowHomeEnabled(true);
Please Help me!!

Add this inside onCreate() of your tabbed activity,
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
And for navigating back, you need to override following method in your tabbed activity.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
onBackPressed();
}
return super.onOptionsItemSelected(item);
}
Happy coding.

Add this method to your activity to navigate back.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();// or the action you want to do eg. Removing fragment
break;
}
return super.onOptionsItemSelected(item);
}

Prevent NavigationDrawer from opening on Home Button Click

I have a NavigationDrawer for my main activity, in one instance I show a fragment and the "Hamburger menu" changes into an arrow.
I disabled the ability to open the drawer via swipe when that fragment is shown by using this
mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);
and it works fine but now the problem is the user can still open the drawer by clicking the home button "Arrow". I want the arrow to act as the back button and not open the drawer so how can I stop the drawer from opening?

I guess you need to use setNavigationOnClickListener() on toolbar to override drawer behavior.
Like -
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// logic to decide if drawer open/close, or pop fragment etc
}
});
This does prevents drawer from opening by clicking on icon. But it does open by swiping. But that you already taken care of. So this should work.
Note This works only after you set ActionBarDrawerToggle by calling
mDrawerToggle = new ActionBarDrawerToggle(getActivity(), mDrawerLayout, toolbar, R.string.openDrawer, R.string.closeDrawer){ ...

Put this on your Activity:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getId() == android.R.id.home){
doSomething(); //can be a finish()
}
}
Or, from this answer
mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
popStackIfNeeded();
mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);
mActionBar.setDisplayHomeAsUpEnabled(false);
mDrawerToggle.setDrawerIndicatorEnabled(true);
}
});

You could try overriding onOptionsItemSelected check for the id android.R.id.home and call finish() to go back to your previous activity.

try to override on options item select.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home :
// do what you want
return true;
}
return true;
}