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Android 应用程序在方向更改时重新启动

转载 作者：行者123 更新时间：2023-11-29 15:18:19 27 4
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我的应用程序包含 fragment ，它主要是 fragment 应用程序。我只有3个 Activity ，其他都是 fragment 。但是，当我在横向模式或纵向模式下旋转手机时，从应用程序的任何一点开始，应用程序都会重新启动并从应用程序的起点继续，从头开始。我把 android:configChanges="orientation|keyboardHidden|keyboard" 放在 Manifest 中，但它似乎根本没有效果。我只用一个 WebView 填充 fragment 。但我也改变了 Action 条的颜色。这就是我在应用程序中所做的一切。这是一个静态应用程序，没有用户输入。这是我的 fragment 的示例代码:

public class CLASSNAME extends Fragment {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.setRetainInstance(true);
}

@Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.LAYOUT, container, false);
    ActionBar bar = getActivity().getActionBar();
    bar.setBackgroundDrawable(new ColorDrawable(getResources().getColor(R.color.COLOR)));
    bar.setTitle("TITLE");


    final WebView wFirst = (WebView) view.findViewById(R.id.WEBVIEWID);
    wFirst.getSettings().setJavaScriptEnabled(true);
    wFirst.setBackgroundColor(0x00000000);

    wFirst.loadDataWithBaseURL(LOADING DATA);
    wFirst.setWebViewClient(new WebViewClient() {SETTING UP WEBVIEW CLIENT});

return view;
}
}

我阅读了很多通过保存实例状态和其他方法得到解答的帖子，但就我而言，我不知道要保存什么，也不知道如何在方向改变的情况下保持我的 Activity 滚动。

这是 MainActivity.class 代码:

public class MainActivity extends Activity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    private static CharSequence mTitle;
    public static Context context;

    public static Context getContext() {
        return context;
    }

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

        context = getApplicationContext();

        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        android.os.Process.killProcess(android.os.Process.myPid());
        super.onDestroy();
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
        finish();
    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getFragmentManager();

        switch (position) {
            case 1:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new AlgebraicGraphs())
                        .commit();
                break;
            case 2:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new Logarithms())
                        .commit();
                break;
            case 3:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new Polynomials())
                        .commit();
                break;
            case 4:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new Powers())
                        .commit();
                break;
            case 6:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new AreaFormulas())
                        .commit();
                break;
            case 7:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new SurfaceAreaFormulas())
                        .commit();
                break;
            case 8:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new PerimeterFormulas())
                        .commit();
                break;
            case 9:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new VolumeFormulas())
                        .commit();
                break;
            case 11:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new TrigonometryGraphsFormulas())
                        .commit();
                break;
            case 12:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new HyperbolicIdentities())
                        .commit();
                break;
            case 13:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new TrigonometricIdentities())
                        .commit();
                break;
            case 16:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new IntegralIdentities())
                        .commit();
                break;
            case 17:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new IntegralSpecialFunctions())
                        .commit();
                break;
            case 18:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new TableOfIntegrals())
                        .commit();
                break;
            case 20:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new DerivativeIdentities())
                        .commit();
                break;
            case 21:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new TableOfDerivatives())
                        .commit();
                break;
            default:
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new DefaultLayout())
                        .commit();
                break;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_about) {
            About about = new About();
            about.show(getFragmentManager(), "about");
        }
        return false;
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }
    }
}

这是日志:

02-19 06:41:24.849    9788-9788/l.pocketformulas E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.IllegalStateException: Fragment Logarithms{4132f5d0} not attached to Activity
            at android.app.Fragment.getResources(Fragment.java:828)
            at l.pocketformulas.Logarithms$1.onPageFinished(Logarithms.java:71)
            at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:444)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:155)
            at android.app.ActivityThread.main(ActivityThread.java:5520)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:796)
            at dalvik.system.NativeStart.main(Native Method)

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