Develop Reference

android.R.id.home is not working in BottomAppbar in My Activity

I am trying to create Navigation View in Bottom App bar in Activity but android.R.id.home doesn't work . I have set the BottomAppbar object as setSupportActionBar(mBottomAppBar) but doesn't work
mBottomAppBar.setOnMenuItemClickListener(new Toolbar.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
switch (item.getItemId()){
case R.id.emp_menu_home:
setFragment(empHomeFragment);
break;
case R.id.emp_menu_notif:
setFragment(notificationsFragment);
break;
case R.id.emp_menu_Inbox:
setFragment(inboxFragment);
break;
case R.id.emp_menu_cv:
setFragment(cvFragment);
break;
case android.R.id.home:
Toast.makeText(Main2Activity.this, "Home is click", Toast.LENGTH_SHORT).show();
NaviDrawerFragment naviDrawerFragment=new NaviDrawerFragment();
naviDrawerFragment.show(getSupportFragmentManager(),naviDrawerFragment.getTag());
break;
default:
return false;
}
return true;
}
});

Try adding: setHasOptionsMenu(true); in your onCreate().
or
If you're using the new Toolbar and ActionbarDrawerToggle. You can assign clickHandler directly. For my activities that have this drawer toolbar I implemented an interface to enable drawer if at root,
#Override
public void enableDrawer(boolean enable) {
mDrawerToggle.setDrawerIndicatorEnabled(enable);
mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Pop fragment back stack or pass in a custom click handler from the fragment.
}
});
}

How to go back to previous activite(s)?

so i have Activity A,B, and C. Activity A & B both go to activity C. When i am on activity C and I press the back home button on mySupportActionBar, I want to return to the state of activity (from the state i left it in) I came from. How would i accomplish this?
Here is my onOptionsItemSelected(). So currently, it goes back to the designated parent activity i assigned in manifest to avoid my app from crashing. Because the parent activites require strings from intents.
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
int id = item.getItemId();
if(id == android.R.id.home)
{
NavUtils.navigateUpFromSameTask(this);
}
return super.onOptionsItemSelected(item);
}
I would also love to accomplish this onBackPressed().

The back arrow button is the "home" button when you're in a inner activity so you could finish the inner activity or maybe just call the back button
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
default:
return super.onOptionsItemSelected(item);
}
}

Use android.R.id.home
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}

You also can use setNavigationOnClickListener on toolbar to trigger back button.
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_filter_category);
setSupportActionBar(toolbar);
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowTitleEnabled(false);
//back button action
toolbar.setNavigationOnClickListener(view -> finish());
}
}

Fragment menu calling activity menu

I have an activity menu and on one fragment I want to replace an item inside that menu. The item when pressed launches an activity. My fragment menu item works, but it also calls the activity menu item intent. I need to remove the duplicate main activity menu item being selected too.
Main Activity menu:
public boolean onOptionsItemSelected(MenuItem item) {
else if(itemId == R.id.action_settings)
startActivity (new Intent(getApplicationContext(),
PreferencesActivity.class));
return super.onOptionsItemSelected(item);
}
Fragment menu:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_settings:
startActivity(new Intent(getActivity(),
PreferencesFragment.class));
return false;
default:
break;
}
return false;
}

It is only if the activity doesn't use the action that it is passed to the fragment. You may be able to add in the activity a boolean that causes the switch to be bypassed for that item.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (!isMyFragmentPresent()) {
switch (item.getItemId()) {
case R.id.action_settings:
startActivity(new Intent(getApplicationContext(),
PreferencesActivity.class));
return true;
default:
break;
}
}
return false;
}
public void setMyFragmentIsPresent(boolean isMyFragmentPresent) {
this.isMyFragmentPresent = isMyFragmentPresent;
}
UPDATE: I realise this doesn't work if you have more items than the one you want to change. Maybe you would be better having a default Fragment that loads in the activity that does nothing but load the R.id.action_settings settings button and what it does. This fragment would then be replaced by your new Fragment.

How to find out the String ID of an item in the Menu knowing its decimal value?

I am using android-support-v7-appcompat.
In an activity I want to show in the actionbar the back button.
I do:
public class News extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_news_screen);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(false);
}
}
And:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
System.out.println(item.getItemId()); // 16908332
System.out.println(R.id.home); // 2131034132
System.out.println(R.id.homeAsUp); // 2131034117
switch(item.getItemId())
{
case R.id.home:
onBackPressed();
break;
case R.id.homeAsUp:
onBackPressed();
break;
case 16908332:
onBackPressed(); // it's works
break;
default:
return super.onOptionsItemSelected(item);
}
return true;
}
If I use numerical filter by id works, but I think that ID is generated by R and therefore can change, is therefore used R.id. . Any idea?

The home/back icon in the actionbar has the id android.R.id.home.
You can look for that id.
The values in android.R.* will never change and are linked statically.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.home:
onBackPressed();
break;
case R.id.homeAsUp:
onBackPressed();
break;
case android.R.id.home:
onBackPressed();
break;
default:
return super.onOptionsItemSelected(item);
}
return true;
}

why it don't work when I click back arrow icon?

I set the following code in my activity:
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return super.onOptionsItemSelected(item);
}
Why it can't work, when i click back arrow icon?

You need implement it by yourself：
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
finish();
break;
default:
break;
}
return super.onOptionsItemSelected(item);
}