菜单未显示在应用程序中

由于某种原因，我的操作菜单在我的 Android Studio 应用程序中消失了。我正在按照教程学习如何创建 Android 应用程序，但最终遇到了这个问题。

我正在使用 atm 的教程：http://www.raywenderlich.com/56109/make-first-android-app-part-2 http://www.raywenderlich.com/56109/make-first-android-app-part-2

这是我的 main.xml 的样子：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- Share item -->
    <item
        android:id="@+id/menu_item_share"
        android:showAsAction="ifRoom"
        android:title="Share"
        android:actionProviderClass= "android.widget.ShareActionProvider" />
</menu>

菜单_main.xml：

<!-- Defines the menu item that will appear on the Action Bar in MainActivity -->
<menu xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- Share item -->
    <item
        android:id="@+id/menu_item_share"
        android:showAsAction="ifRoom"
        android:title="Share"
        android:actionProviderClass= "android.widget.ShareActionProvider"
        tools:ignore="AppCompatResource" />
</menu>

我在这段代码中做错了什么？我没有收到任何错误。我几乎是从教程中复制粘贴的。

我不认为这是我的java代码，但仍然在这里，以防有人认为问题出在该代码中。 MainActivity.java：

package android.stefan.testappnieuw;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;


public class MainActivity extends Activity implements View.OnClickListener, AdapterView.OnItemClickListener {

    TextView mainTextView;
    Button mainButton;
    EditText mainEditText;
    ListView mainListView;
    ArrayAdapter mArrayAdapter;
    ArrayList mNameList = new ArrayList();
    android.widget.ShareActionProvider mShareActionProvider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 1. Access the TextView defined in layout XML
        // and then set its text
        mainTextView = (TextView) findViewById(R.id.main_textview);
        mainTextView.setText("Set in Java!");
        // 2. Access the Button defined in layout XML
        // and listen for it here
        mainButton = (Button) findViewById(R.id.main_button);
        mainButton.setOnClickListener(this);
        // 3. Access the EditText defined in layout XML
        mainEditText = (EditText) findViewById(R.id.main_edittext);
        // 4. Access the ListView
        mainListView = (ListView) findViewById(R.id.main_listview);
        // 5. Set this activity to react to list items being pressed
        mainListView.setOnItemClickListener(this);

        // Create an ArrayAdapter for the ListView
        mArrayAdapter = new ArrayAdapter(this,
                android.R.layout.simple_list_item_1,
                mNameList);

        // Set the ListView to use the ArrayAdapter
        mainListView.setAdapter(mArrayAdapter);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu.
        // Adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);

        // Access the Share Item defined in menu XML
        MenuItem shareItem = menu.findItem(R.id.menu_item_share);

        // Access the object responsible for
        // putting together the sharing submenu
        if (shareItem != null) {
            mShareActionProvider = (android.widget.ShareActionProvider)shareItem.getActionProvider();
        }

        // Create an Intent to share your content
        setShareIntent();

        return true;
    }

    private void setShareIntent() {

        if (mShareActionProvider != null) {

            // create an Intent with the contents of the TextView
            Intent shareIntent = new Intent(Intent.ACTION_SEND);
            shareIntent.setType("text/plain");
            shareIntent.putExtra(Intent.EXTRA_SUBJECT, "Android Development");
            shareIntent.putExtra(Intent.EXTRA_TEXT, mainTextView.getText());

            // Make sure the provider knows
            // it should work with that Intent
            mShareActionProvider.setShareIntent(shareIntent);
        }
    }

    @Override
    public void onClick(View v) {
        // Take what was typed into the EditText
        // and use in TextView
        mainTextView.setText(mainEditText.getText().toString()
                + " Hallo");
        // Also add that value to the list shown in the ListView
        mNameList.add(mainEditText.getText().toString());
        mArrayAdapter.notifyDataSetChanged();
        // 6. The text you'd like to share has changed,
        // and you need to update
        setShareIntent();
    }

    @Override
    public void onItemClick(AdapterView parent, View view, int position, long id) {
        // Log the item's position and contents
        // to the console in Debug
        Log.d("omg android", position + ": " + mNameList.get(position));
    }
}

我真的不知道出了什么问题，我是 java/android 新手，由于某种原因，菜单栏显示在教程中，但不适合我。

感谢您的阅读/帮助！

转到您的清单文件并添加或更改此应用程序属性，如果不可用，请查找类似的内容，还有更多使用操作栏

android:theme="@style/ThemeOverlay.AppCompat.ActionBar" >