我开始创建一个使用一个活动(Navigation Drawer)和多个片段的应用程序。
但是我无法使用工具栏返回按钮从片段中导航回来。硬件返回按钮完美地工作。我知道我需要覆盖onOptionsItemSelected
,捕获android.R.id.home
,检查后退堆栈是否有内容,然后弹出它。更改片段后,“汉堡包”按钮会变成“返回箭头”,但当我单击它时,onOptionsItemSelected
从未触发,只打开 NavigationDrawer 菜单。
这里是活动页面的代码:
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();
}
}
我如何替换来自HomeFragment
的片段:
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();
onCreateOptionsMenu()
。 - terencey