问题
I started creating of app which use one activity (Navigation Drawer) and many fragments.
But I unable to use toolbar back button to navigate back from fragments. Hardware back button works perfectly. I know that I need to override onOptionsItemSelected, catch android.R.id.home, check if there are something in back stack and than pop it. After changing fragment, "burger" button changes to "back arrow", but when I click on it onOptionsItemSelected never fired, just opens the NavigationDrawer menu.
Here the code from activity:
public class NavDrawerActivity extends AppCompatActivity implements ... {
NavigationView navigationView;
BottomNavigationView bottomNavigationView;
ActionBarDrawerToggle toggle;
FragmentManager fragmentManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nav_drawer);
fragmentManager = getSupportFragmentManager();
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
// Set back button
fragmentManager.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
@Override
public void onBackStackChanged() {
if (fragmentManager.getBackStackEntryCount() > 0) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
} else {
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
toggle.syncState();
}
}
});
// Load default fragment
changeFragment(new HomeFragment(), false);
navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
View headerLayout = navigationView.getHeaderView(0);
bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottom_navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(this);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
Toast.makeText(this, "Back pressed", Toast.LENGTH_SHORT)
.show();
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START))
drawer.closeDrawer(GravityCompat.START);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (fragmentManager.getBackStackEntryCount() > 0) {
fragmentManager.popBackStack();
} else {
super.onBackPressed();
}
}
private void changeFragment(Fragment fm, boolean addToBackStack)
{
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.frame_layout_content, fm);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
if (addToBackStack) ft.addToBackStack(null);
ft.commit();
}
}
And how I change (replace) fragments from HomeFragment:
IndexDetailFragment newFragment = new IndexDetailFragment();
Bundle args = new Bundle();
args.putString(IndexDetailFragment.ARG_INDEX_ID, id);
newFragment.setArguments(args);
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left);
transaction.replace(R.id.frame_layout_content, newFragment);
transaction.addToBackStack(null);
transaction.commit();
回答1:
setNavigationOnClick() on the toolbar after setSupportActionBar(toolbar) :
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
Toast.makeText(getActivity(), "Back clicked!",
Toast.LENGTH_SHORT).show();
}
});
I have made a small app for reference
FirstFragment
public class FirstFragment extends Fragment {
public FirstFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_first, container, false);
}
}
SecondFragment
public class SecondFragment extends Fragment {
public SecondFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_second, container, false);
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
private Toolbar mToolbar;
private ActionBarDrawerToggle drawerToggle;
private DrawerLayout mDrawerLayout;
private String TAG = "MainActivity";
private FragmentManager mFragmentManager;
private NavigationView mNavigationView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mToolbar = (Toolbar) findViewById(R.id.toolbar);
if (mToolbar != null) {
setSupportActionBar(mToolbar);
}
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer);
drawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.drawer_open, R.string.drawer_close) {
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
}
@Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
}
};
mDrawerLayout.addDrawerListener(drawerToggle);
mNavigationView = findViewById(R.id.navigation);
mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.first:
changeFragment(new FirstFragment(), true);
return true;
case R.id.second:
changeFragment(new SecondFragment(), true);
return true;
}
return false;
}
});
mFragmentManager = getSupportFragmentManager();
changeFragment(new FirstFragment(), true);
}
@Override
protected void onPostCreate(@Nullable Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
if (drawerToggle != null) {
drawerToggle.syncState();
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
Log.i(TAG, "onOptionsItemSelected: Home Button Clicked");
if (mDrawerLayout.isDrawerOpen(Gravity.START)) {
mDrawerLayout.closeDrawer(Gravity.START);
} else {
mDrawerLayout.openDrawer(Gravity.START);
}
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
if (mDrawerLayout.isDrawerOpen(Gravity.START)) {
mDrawerLayout.closeDrawer(Gravity.START);
}
if (mDrawerLayout.isDrawerOpen(Gravity.START)) {
mDrawerLayout.closeDrawer(Gravity.START);
} else if (mFragmentManager.getBackStackEntryCount() > 0) {
mFragmentManager.popBackStack();
} else {
super.onBackPressed();
}
}
private void changeFragment(Fragment fragment, boolean needToAddBackstack) {
FragmentTransaction mFragmentTransaction = mFragmentManager.beginTransaction();
mFragmentTransaction.replace(R.id.FRAME_CONTENT, fragment);
mFragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
if (needToAddBackstack)
mFragmentTransaction.addToBackStack(null);
mFragmentTransaction.commit();
}
}
activity_main
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="@dimen/abc_action_bar_default_height_material"
android:background="@color/colorPrimaryDark"
/>
<FrameLayout
android:id="@+id/FRAME_CONTENT"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="@dimen/abc_action_bar_default_height_material" />
</FrameLayout>
<android.support.design.widget.NavigationView
android:id="@+id/navigation"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:layout_marginTop="@dimen/abc_action_bar_default_height_material"
app:menu="@menu/drawermenu" />
</android.support.v4.widget.DrawerLayout>
回答2:
I had the same issue.
I finally solved by adding this in the onCreate method.
getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
@Override
public void onBackStackChanged() {
if(getSupportFragmentManager().getBackStackEntryCount() == 0){
drawer.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);
menuToggle.setDrawerIndicatorEnabled(true);
}else{
drawer.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);
menuToggle.setDrawerIndicatorEnabled(false);
}
}
});
Hope it helps
回答3:
Add below code in onCreate() method that's work for me
getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
@Override
public void onBackStackChanged() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, " Back Pressed ", Toast.LENGTH_SHORT).show();
}
});
} else {
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
drawerToggle = new ActionBarDrawerToggle(MainActivity.this, drawerLayout, toolbar,
R.string.app_name, R.string.app_name);
drawerLayout.addDrawerListener(drawerToggle);
drawerToggle.syncState();
}
}
});
来源：https://stackoverflow.com/questions/48185871/navigation-drawer-back-button-in-fragments