Android 将底部导航视图实现为一个片段
在我的Android Studio项目中,我想在MainActivity中实现一个带有片段的NavigationDrawer,在每个片段上实现一个底部导航视图 这是一个片段的代码:Android 将底部导航视图实现为一个片段,android,android-layout,android-fragments,Android,Android Layout,Android Fragments,在我的Android Studio项目中,我想在MainActivity中实现一个带有片段的NavigationDrawer,在每个片段上实现一个底部导航视图 这是一个片段的代码: public class U16 extends Fragment{ @Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { super.onViewCreated(view, savedIn
public class U16 extends Fragment{
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
getActivity().setTitle("TITOLO U16");
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
switch (item.getItemId()) {
case R.id.navigation_home:
fragmentTransaction.replace(R.id.content, new Calendario()).commit();
return true;
case R.id.navigation_dashboard:
fragmentTransaction.replace(R.id.content, new Palestre()).commit();
return true;
case R.id.navigation_notifications:
fragmentTransaction.replace(R.id.content, new Squadra()).commit();
return true;
}
return false;
}
};
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
BottomNavigationView navigation = (BottomNavigationView) getActivity().findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.content, new Calendario()).commit();
return inflater.inflate(R.layout.u16_layout, container, false);
}
}
我得到这个错误:
FATAL EXCEPTION: main
Process: app.navigationdrawerfragment, PID: 21499
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.BottomNavigationView.setOnNavigationItemSelectedListener(android.support.design.widget.BottomNavigationView$OnNavigationItemSelectedListener)' on a null object reference at app.navigationdrawerfragment.U16.onCreateView(U16.java:52)
我知道,这个错误在“OnCreateView”执行“navigation.setOnNavigationItemSelectedListener”过程中出现了
这是u16_layout.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="simone.biliato.navigationdrawerfragment.MainActivity">
<FrameLayout
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="?android:attr/windowBackground"
app:menu="@menu/navigation" />
</LinearLayout>
那么,有人也尝试过这样做吗?您正在尝试设置一个尚未创建的人。 因此,将代码移动到事件onViewCreated中,如下所示:
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
getActivity().setTitle("Titolo");
BottomNavigationView navigation = (BottomNavigationView) getActivity().findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.content, new Calendario()).commit();
return inflater.inflate(R.layout.u16_layout, container, false);
}
这将起作用:)你能在这里发布与此
片段相关的活动的布局吗。我用布局编辑了第一个问题有人能帮我吗?请:(