菜单没有出现在Fragment中(menu not appearing in Fragment)

我正在尝试将菜单放入我的应用程序中的片段中。但是，当我运行它时，菜单不会出现。我对在片段中显示菜单所涉及的步骤的理解（如果我错了或缺少某些东西，请纠正我）是你做了以下事情：

在res / menu目录中创建菜单资源文件。覆盖onCreateOptionsMenu(Menu, MenuInflater)并在所述方法中，膨胀由菜单资源ID定义的布局。通过在片段的onCreate方法中调用setHasOptionsMenu(true) ，通知片段管理器该片段应该接收对onCreateOptionsMenu的调用。

我已经编写了我的代码的简化版本，只包括（我相信）应该显示菜单的最低限度。谁能告诉我这段代码中缺少什么？

这是我的菜单资源xml：

<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/menu_item_1" android:icon="@android:drawable/ic_menu_add" android:title="@string/menu_item_text" android:showAsAction="ifRoom|withText"/> </menu>

我的片段代码：

import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.View; import android.view.ViewGroup; public class MainFragment extends Fragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); } public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); inflater.inflate(R.menu.fragment_menu, menu); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.fragment_main, parent, false); return v; } }

我的活动代码：

package com.bignerdranch.android.fragmentmenuexample; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v7.app.ActionBarActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; public class MainActivity extends FragmentActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); FragmentManager fm = getSupportFragmentManager(); Fragment fragment = fm.findFragmentById(R.id.fragmentContainer); if (fragment == null) { fragment = new MainFragment(); fm.beginTransaction() .add(R.id.fragmentContainer, fragment) .commit(); } } }

我的清单：

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.bignerdranch.android.fragmentmenuexample" > <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

我在运行IceCreamSandwich的AVD Galaxy Nexus上运行它。

I'm attempting to put a menu into a fragment in my app. However, the menu isn't appearing when I run it. My understanding of the steps involved in making a menu display in a fragment (and please correct me if I'm wrong or missing something) is that you do the following:

Create a menu resource file in the res/menu directory. Override onCreateOptionsMenu(Menu, MenuInflater) and within said method, inflate the layout defined by the menu resource ID. Notify the fragment manager that this fragment should receive a call to onCreateOptionsMenu by calling setHasOptionsMenu(true) in the fragment's onCreate method.

I've written a reduced version of my code to only include the bare minimum of what (I believe) should show a menu. Can anyone tell me what's missing from this code?

Here is my menu resource xml:

<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/menu_item_1" android:icon="@android:drawable/ic_menu_add" android:title="@string/menu_item_text" android:showAsAction="ifRoom|withText"/> </menu>

My fragment code:

import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.View; import android.view.ViewGroup; public class MainFragment extends Fragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); } public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); inflater.inflate(R.menu.fragment_menu, menu); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.fragment_main, parent, false); return v; } }

And my activity code:

package com.bignerdranch.android.fragmentmenuexample; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v7.app.ActionBarActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; public class MainActivity extends FragmentActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); FragmentManager fm = getSupportFragmentManager(); Fragment fragment = fm.findFragmentById(R.id.fragmentContainer); if (fragment == null) { fragment = new MainFragment(); fm.beginTransaction() .add(R.id.fragmentContainer, fragment) .commit(); } } }

And my manifest:

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.bignerdranch.android.fragmentmenuexample" > <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

I'm running this on an AVD Galaxy Nexus running IceCreamSandwich.