我正在尝试使用android-support-v7:21库创建简单的应用程序。代码fragment:MainActivity.javapublicclassMainActivityextendsActionBarActivity{ToolbarmActionBarToolbar;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mActionBarToolbar=(Toolba

我正在尝试使用android-support-v7:21库创建简单的应用程序。代码fragment:MainActivity.javapublicclassMainActivityextendsActionBarActivity{ToolbarmActionBarToolbar;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mActionBarToolbar=(Toolba