android - 为什么此代码中未显示选项菜单

Question

为什么选项菜单不显示在此代码中，而选项菜单在空白片段中清除

BasicActivity.java - 这是我的第一个入口代码

public class BasicActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_basic);
        FragmentLoader.loadFragment(this, R.id.container, new BlankFragment());
    }

      @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        boolean retVal = super.onCreateOptionsMenu(menu);
        return retVal;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

activity_basic.xml 基本活动的 xml 文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BasicActivity">

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

BlankFragment.java - 当我包含工具栏选项时，它会出现，但此片段中的选项菜单不会出现

public class BlankFragment extends Fragment {

    private static final String TAG = BlankFragment.class.getName();


    // TODO: Customize parameter initialization
    @SuppressWarnings("unused")
    public static BlankFragment newInstance( ) {
        BlankFragment fragment = new BlankFragment();
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setRetainInstance(true);
        setHasOptionsMenu(true);

       
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_blank, container, false);

        return view;
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        inflater.inflate(R.menu.episodes, menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        return super.onOptionsItemSelected(item);
    }
}

片段空白.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BlankFragment" >
    <!--    tools:context=".MainActivity2">-->

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="180dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        tools:ignore="InconsistentLayout"
        android:theme="@style/Theme.Fragment.AppBarOverlay"
        android:fitsSystemWindows="true" >

        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/chat_toolbar_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            android:background="@color/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:toolbarId="@+id/toolbar">

            <ImageView
                android:id="@+id/mainAppbarImage"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:gravity="center"
                android:minHeight="?actionBarSize"
                android:padding="10dp"
                android:text="@string/app_name"
                android:textAppearance="@style/TextAppearance.Widget.AppCompat.Toolbar.Title" />

            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/Theme.Fragment.PopupOverlay" >

<!--                <include layout="@layout/layout_main_toolbar" />-->

            </androidx.appcompat.widget.Toolbar>


        </com.google.android.material.appbar.CollapsingToolbarLayout>
    </com.google.android.material.appbar.AppBarLayout>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/chat_fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@mipmap/ic_forward"
        app:backgroundTint="@color/colorPrimary"/>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

标签： android