Question

我正在创建一个简单的应用程序管理器来训练自己开发Android应用程序。我希望我的操作栏（actionbarcompat）有下拉导航+标题+副标题，我设法通过创建自定义适配器来实现，但我不知道如何让我的操作栏使用该微调器适配器。所以我做了一个简单的研究，我终于设法通过“setListNavigationCallbacks”实现我的目标，将我的适配器作为第一个参数传递，并将“OnNavigationListener”作为第二个参数。但我有两个问题：

我不熟悉听众及其工作方式，我想知道是否可以将适配器设置为我的操作栏（getSupportActionBar）并稍后捕获回调？
即使这段代码有效，每次切换布局时都会崩溃（即当我从纵向切换到横向，反之亦然）时，我知道问题出在setListNavigationCallbacks方法，因为当我删除它时在纵向或横向中运行没有问题，但我的样式没有得到应用。

这是我的代码（我使用片段来显示已安装的应用程序）：

MainActivity.java

public class MainActivity extends ActionBarActivity {

private FragmentTransaction fragmentTransaction = getSupportFragmentManager ( ).beginTransaction ( );

@Override
protected void onCreate ( Bundle savedInstanceState ) {

    super.onCreate ( savedInstanceState );

    setContentView ( R.layout.activity_main );

    getSupportActionBar ( ).setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
    getSupportActionBar ( ).setTitle("");

    if ( findViewById ( R.id.activity_application_manager_framelayout ) != null && savedInstanceState == null ) {

        ApplicationsListFragment applicationsListFragment = new ApplicationsListFragment ( );

        applicationsListFragment.setArguments ( getIntent ( ).getExtras ( ) );
        fragmentTransaction.add ( R.id.activity_application_manager_framelayout , applicationsListFragment ).commit ( );

    }

}

@Override
public boolean onCreateOptionsMenu ( Menu menu ) {

    getMenuInflater ( ).inflate ( R.menu.main , menu );

    return true;

}

}

ApplicationListFragment.java

public class ApplicationsListFragment extends ListFragment {

private ListView listView;
private ApplicationManager applicationManager;
private ActionBar actionBar;
private CustomAdapter customAdapter;
private CustomAdapter.ActionBarDropDownCustomAdapter actionBarDropDownCustomAdapter;
private CustomAdapter.ApplicationsListCustomAdapter applicationsListCustomAdapter;
private List < ApplicationInfo > applications = new ArrayList < ApplicationInfo > ( );
private List < String > actionBarDropDownItems = new ArrayList < String > ( );

@Override
public View onCreateView ( LayoutInflater inflater , ViewGroup container , Bundle savedInstanceState ) {

    View view = inflater.inflate ( R.layout.fragment_applications_list , container , false );
    this.listView = ( ListView ) view.findViewById ( android.R.id.list );

    this.actionBarDropDownItems.add ( "All Apps" );
    this.actionBarDropDownItems.add ( "User Apps" );
    this.actionBarDropDownItems.add ( "System Apps" );

    customAdapter = new CustomAdapter ( );
    actionBarDropDownCustomAdapter = customAdapter.new ActionBarDropDownCustomAdapter ( getActivity ( ) , R.layout.spinner_activity_main_actionbar , R.layout.list_item_activity_main_actionbar , this.actionBarDropDownItems );

    actionBar.setListNavigationCallbacks ( actionBarDropDownCustomAdapter , new OnNavigationListener( ) {

        @Override
        public boolean onNavigationItemSelected ( int arg0 , long arg1 ) {

            if ( actionBarDropDownItems.get ( arg0 ).equals ( actionBarDropDownItems.get ( 0 ) ) ) {

                refreshDisplay ( 0 );

            } else if ( actionBarDropDownItems.get ( arg0 ).equals ( actionBarDropDownItems.get ( 1 ) ) ) {

                refreshDisplay ( 1 );

            } else if ( actionBarDropDownItems.get ( arg0 ).equals ( actionBarDropDownItems.get ( 2 ) ) ) {

                refreshDisplay ( 2 );

            }

            return false;

        }

    } );

    return view;

}

@Override
public void onActivityCreated ( Bundle savedInstanceState ) {

    super.onActivityCreated ( savedInstanceState );

    this.applicationManager = new ApplicationManager ( getActivity() );

    refreshDisplay ( 0 );

}

@Override
public void onAttach ( Activity activity ) {

    super.onAttach ( activity );

    actionBar = ( ( ActionBarActivity ) activity ).getSupportActionBar ( );

}

public boolean refreshDisplay ( int flag ) {

    if ( flag == 0 ) {

        this.applications = this.applicationManager.getAllAppInfos ( );
        this.applicationsListCustomAdapter = customAdapter.new ApplicationsListCustomAdapter ( getActivity() , R.layout.list_item_fragment_applications_list , this.applications );
        this.listView.setAdapter ( applicationsListCustomAdapter );

        return true;

    } else if ( flag == 1 ) {

        this.applications = this.applicationManager.getAllUserAppInfos ( );
        this.applicationsListCustomAdapter = customAdapter.new ApplicationsListCustomAdapter ( getActivity() , R.layout.list_item_fragment_applications_list , this.applications );
        this.listView.setAdapter ( applicationsListCustomAdapter );

        return true;

    } else if ( flag == 2 ) {

        this.applications = this.applicationManager.getAllSystemAppInfos ( );
        this.applicationsListCustomAdapter = customAdapter.new ApplicationsListCustomAdapter ( getActivity() , R.layout.list_item_fragment_applications_list , this.applications );
        this.listView.setAdapter ( applicationsListCustomAdapter );

        return true;

    } else {

        return false;

    }

}

}

Answer 1

我找到了解决这两个问题的方法，所以我想我和你们分享了这些问题：

1 - 在类中实现“ActionBar.OnNavigationListener”，然后覆盖类中的“onNavigationItemSelected”方法，最后将类作为“setListNavigationCallbacks”的第二个参数传入（使用“this”关键字）当然）

2 - 你必须覆盖你的活动的“onSaveInstanceState”方法（而不是片段）并在“savedInstanceState”中放入一个整数（getSupportActionBar（）。getSelectedNavigationIndex（）），你覆盖你的“onRestoreInstanceState”方法activity并将“getSupportActionBar（）。setSelectedNavigationItem（）”设置为您在“onSaveInstanceState”中保存的值。

切换到横向后，setListNavigationCallbacks会崩溃应用程序

1 个答案: