我正在尝试处理 NavigationView点击侦听器的后退按钮，但它无法正常工作。
DispatchQueue.global(qos: .default).async {
// ...
}
可能已经足够，但可能是由于其他原因导致为什么要添加全班
MainActivity.class
navigationView.setOnClickListenerMike M发现的答案评论：
删除public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private ActionBarDrawerToggle toggle;
private DrawerLayout drawerLayout;
private NavigationView navigationView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
resetActionBar();
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
toggle = new ActionBarDrawerToggle(
this, drawerLayout, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawerLayout.addDrawerListener(toggle);
toggle.syncState();
navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
navigationView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (getSupportFragmentManager().getBackStackEntryCount() > 0)
onBackPressed();
}
});
getSupportFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE).replace(R.id.content_fragment, new CameraFragment()).commit();
}
@Override
public void onBackPressed() {
//super.onBackPressed();
if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
drawerLayout.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if(id == android.R.id.home)
{
if (getSupportFragmentManager().getBackStackEntryCount() > 0)
onBackPressed();
else
drawerLayout.openDrawer(navigationView);
return true;
}else if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
Fragment fragment = null;
if (id == R.id.nav_camera) {
// Handle the camera action
fragment = new CameraFragment();
} else if (id == R.id.nav_gallery) {
fragment = new GalleryFragment();
} else if (id == R.id.nav_slideshow) {
fragment = new SlideShowFragment();
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if(fragment!=null){
if(item.isChecked())
{
if(getSupportFragmentManager().getBackStackEntryCount()==0){
drawer.closeDrawers();
}else{
removeAllFragments();
getSupportFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE).replace(R.id.content_fragment, fragment).commit();
drawer.closeDrawer(GravityCompat.START);
}
}else{
removeAllFragments();
getSupportFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE).replace(R.id.content_fragment, fragment).commit();
drawer.closeDrawer(GravityCompat.START);
}
}
drawer.closeDrawer(GravityCompat.START);
return true;
}
public void removeAllFragments(){
getSupportFragmentManager().popBackStackImmediate(null,
FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
public void replaceFragment(final Fragment fragment) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.replace(R.id.content_fragment, fragment).addToBackStack("")
.commit();
}
public void updateDrawerIcon() {
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
try {
Log.i("", "BackStackCount: " + getSupportFragmentManager().getBackStackEntryCount());
if (getSupportFragmentManager().getBackStackEntryCount() > 0)
toggle.setDrawerIndicatorEnabled(false);
else
toggle.setDrawerIndicatorEnabled(true);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}, 50);
}
public void resetActionBar()
{
//display home
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
}
public void setActionBarTitle(String title) {
getSupportActionBar().setTitle(title);
}
}
并将其替换为
navigation.setOnClickListener