Question

我有一个带有三个标签的TabLayout，每个标签都包含一个ListFragment。这些由SectionsPagerAdapter处理。当旋转屏幕时，似乎他们已经丢失了ListAdapter，因为它们正在加载但没有任何反应： example image

实际上我有很多关于碎片的生命周期的东西，但是我无法为我的问题实现它。

当旋转屏幕时，活动被破坏并再次调用onCreate（）。所以我把以下内容放在那里：

创建ListFragment的新实例
创建CursorAdapter的新实例
设置适配器

那么我的谬误在哪里？

编辑：我现在解决了问题，覆盖了onSaveInstanceState方法。但到底是什么导致了所描述的问题呢？

MainActivity.java：

public class MainActivity extends AppCompatActivity {

    private SectionsPagerAdapter mSectionsPagerAdapter;
    private ViewPager mViewPager;
    FragmentManager mFragmentManager;

    private ProgressDialog pDialog;

    // Fragments for the three Tabs
    public Contact fragment_all;
    public Contact fragment_official;
    public Contact fragment_alumni;

    // Handler for SQLite DB Access
    public DBHandler dbhandler;

    private MemberListAdapter ca_all;
    private MemberListAdapter ca_alu;
    private MemberListAdapter ca_off;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        mFragmentManager = getSupportFragmentManager();
        mSectionsPagerAdapter = new SectionsPagerAdapter(mFragmentManager);

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        fragment_all = new Contact();
        fragment_alumni = new Contact();
        fragment_official = new Contact();

        dbhandler = new DBHandler(this);
        ca_all = new MemberListAdapter(this);
        ca_alu = new MemberListAdapter(this);
        ca_off = new MemberListAdapter(this);

        ca_all.ID = 1;
        ca_alu.ID = 3;
        ca_off.ID = 2;

        fragment_all.setListAdapter(ca_all);
        fragment_alumni.setListAdapter(ca_alu);
        fragment_official.setListAdapter(ca_off);

        updateAdapters();            
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        dbhandler.close();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_activity_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // ...unimportant code
    }


    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {

            if (position == 0){
                return fragment_all;
            }else if (position == 1){
                return fragment_official;
            }else{
                return fragment_alumni;
            }
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return getResources().getString(R.string.title_section1);

                case 1:
                    return getResources().getString(R.string.title_section2);
                case 2:
                    return getResources().getString(R.string.title_section3);
            }
            return null;
        }
    }

    private void updateAdapters() {
        ca_all.changeCursor(dbhandler.query());
        ca_alu.changeCursor(dbhandler.query());
        ca_off.changeCursor(dbhandler.query());
    }
}

layout_main：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    android:background="@color/colorSecond">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/colorContrast"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay">

        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            app:tabMaxWidth="0dp"
            app:tabGravity="fill"
            app:tabMode="fixed"
            android:background="@color/colorContrast"
            android:fillViewport="false"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/container"
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/updatedb" />

</android.support.design.widget.CoordinatorLayout>

ListFragment Contact.java：

public class Contact extends ListFragment {
    private CursorAdapter ca;
    private MemberListAdapter mla;

    @Override
    public void onListItemClick(ListView l, View v, int position, long id){
        mla = (MemberListAdapter) getListAdapter();
        String myid = Integer.toString(mla.ID);

        Log.i("Position: ", Integer.toString(position));
        Log.i("ID: ", myid);
    }

    public Contact(){
        super();

    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
    }
}

CursorAdapter MemberListAdapter.java：

public class MemberListAdapter extends CursorAdapter {
    private LayoutInflater inflator;
    public int ID;

    public MemberListAdapter(Context context) {
        super(context, null, 0);
        inflator = LayoutInflater.from(context);
    }

    @Override
    public int getViewTypeCount() {
        return 3;
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {

        int ciName = cursor.getColumnIndex(DBHandler.USERS_NAME);
        int ciSurname = cursor.getColumnIndex(DBHandler.USERS_SURNAME);
        int ciMail = cursor.getColumnIndex(DBHandler.USERS_MAIL);

        String mail = cursor.getString(ciMail);
        String name = cursor.getString(ciName);
        String surname = cursor.getString(ciSurname);

        ImageView image = (ImageView) view.findViewById(R.id.icon);
        TextView textview1 = (TextView) view.findViewById(R.id.text1);
        TextView textview2 = (TextView) view.findViewById(R.id.text2);

        image.setImageResource(R.drawable.ksatlogo);
        textview1.setText(name + ", " + surname);
        textview2.setText(mail);
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return inflator.inflate(R.layout.icon_text_text, null);
    }
}

Answer 1

尝试添加android：configChanges =＆＃34; orientation＆＃34;在你的清单活动中。

旋转屏幕时ListFragment会崩溃 - Android

1 个答案: