如何訪問菜單項？

Question

因此，我試圖從ActionBar中抓取菜單項，並將其設置為一些變量以備后用。 下面是一些基本的測試代碼，它們試圖在創建選項菜單的過程中設置變量。 當它啟動時，它崩潰並顯示錯誤：

02-18 12:10:08.109: E/AndroidRuntime(30931): FATAL EXCEPTION: main
02-18 12:10:08.109: E/AndroidRuntime(30931): Process: com.example.slider2, PID: 30931
02-18 12:10:08.109: E/AndroidRuntime(30931): java.lang.IndexOutOfBoundsException: Invalid index 2131230720, size is 1
02-18 12:10:08.109: E/AndroidRuntime(30931):    at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at java.util.ArrayList.get(ArrayList.java:308)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.view.menu.MenuBuilder.getItem(MenuBuilder.java:656)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.example.slider2.MainActivity.onCreateOptionsMenu(MainActivity.java:22)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.app.Activity.onCreatePanelMenu(Activity.java:2538)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:436)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.policy.impl.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:800)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.policy.impl.PhoneWindow$1.run(PhoneWindow.java:221)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.view.Choreographer.doCallbacks(Choreographer.java:574)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.view.Choreographer.doFrame(Choreographer.java:543)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.os.Handler.handleCallback(Handler.java:733)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.os.Handler.dispatchMessage(Handler.java:95)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.os.Looper.loop(Looper.java:136)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at android.app.ActivityThread.main(ActivityThread.java:5017)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at java.lang.reflect.Method.invokeNative(Native Method)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at java.lang.reflect.Method.invoke(Method.java:515)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:126)
02-18 12:10:08.109: E/AndroidRuntime(30931):    at dalvik.system.NativeStart.main(Native Method)

MainActivity.java

public class MainActivity extends Activity {

    private MenuItem mRefresh;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        mRefresh = menu.getItem(R.id.refresh);
        return super.onCreateOptionsMenu(menu);
    }
}

main_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:id="@+id/refresh"
        android:icon="@drawable/ic_action_refresh"
        android:showAsAction="ifRoom"
        android:title="@string/refresh"/>
</menu>

對我在這里做錯的任何想法嗎？ 我需要能夠操縱菜單項，而不僅僅是在點擊菜單項時。

Answer 1

MenuItem.getItem（index）采用菜單項的索引而不是菜單項的ID，因此請使用MenuItem.findItem ，其將菜單項ID作為：

 mRefresh = menu.findItem(R.id.refresh); //item id
  OR
 mRefresh = menu.getItem(0); //item index

Answer 2

getItem(int)返回特定索引處的MenuItem，而findItem(int)返回與給定資源ID對應的MenuItem。 調用findItem而不是getItem 。

http://developer.android.com/reference/android/view/Menu.html#findItem(int）