操作栏 sherlock 库中显示空指针异常

我想实现 Sherlock 操作栏的搜索视图小部件。我的问题是OnOptionItemSelected搜索视图项目的。我在库活动中遇到空指针异常。

菜单 XML：

<item android:id="@+id/menu_search"
      android:actionViewClass="com.actionbarsherlock.widget.SearchView"
      android:icon="@android:drawable/ic_menu_search"
/>

选项菜单的代码片段：

public boolean onCreateOptionsMenu(Menu menu) 
{
    MenuInflater inflater = getSupportMenuInflater();
    inflater.inflate(R.menu.tvguide_menu, menu);
    MenuItem mSearch = menu.findItem(R.id.menu_search);
    searchView = new SearchView(getSupportActionBar().getThemedContext());
    searchView.setQueryHint("Search for countries…");
    searchView.setOnQueryTextListener(this);
    mSearch.setActionView(searchView);
    mSearch.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM |
            MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);
}

我在点击搜索 android 时被迫关闭。我在下面分享了我的日志

04-17 15:10:08.508: E/AndroidRuntime(23283): FATAL EXCEPTION: main
04-17 15:10:08.508: E/AndroidRuntime(23283): java.lang.NullPointerException
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.MenuItemImpl.toString(MenuItemImpl.java:490)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at java.lang.StringBuilder.append(StringBuilder.java:202)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.actionbarsherlock.app.SherlockFragmentActivity.onMenuItemSelected(SherlockFragmentActivity.java:201)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:953)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:491)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:110)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.view.View.performClick(View.java:3511)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.view.View$PerformClick.run(View.java:14105)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.os.Handler.handleCallback(Handler.java:605)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.os.Handler.dispatchMessage(Handler.java:92)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.os.Looper.loop(Looper.java:137)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at android.app.ActivityThread.main(ActivityThread.java:4438)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at java.lang.reflect.Method.invokeNative(Native Method)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at java.lang.reflect.Method.invoke(Method.java:511)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-17 15:10:08.508: E/AndroidRuntime(23283):    at dalvik.system.NativeStart.main(Native Method)

问题是你的Menuitem 未指定标题，并且在行中：

@Override
public final boolean onMenuItemSelected(int featureId, android.view.MenuItem item) {
    if (BuildConfig.DEBUG) Log.d(TAG, "[onMenuItemSelected] featureId: " 
           + featureId + ", item: " + item);
    ...
}

item将涉及到toString()方法其中：

@Override
public String toString() {
    return mTitle.toString();
}

会抛出一个NullPointerException。在修复之前，一个简单的解决方法是使用：

android:title=""

为您MenuItem.

此外，在您的应用程序发布时也不会发生这种情况。