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发现问题:

行为是由一些遗留的库项目导入引起的。特别是 ActionBarSherlock 和 SlidingMenuLibrary,它们都没有被使用。

奇怪的问题。

FragmentStatePagerAdapter 似乎正在实例化每个片段,然后在页面滑动时销毁它们。(即实例化所有 100 个片段,并销毁不需要的 97 个) 看看是否有人以前见过这些症状?

刚刚通过多次调用由布局问题引起的 getView 调试 ListView我认为这里可能有类似的东西?在我开始正确调试之前,有人有一些快速的想法吗?

谢谢

更新。附上我试图做的一个简单的工作版本......所以它表明它是可行的。现在只需要调试我的主要代码的笨拙版本:-(一定做了一些愚蠢的事情。

public class MainActivity extends FragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;

private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mPlanetTitles;

private ViewPager mViewPager;

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

    mTitle = mDrawerTitle = getTitle();
    mPlanetTitles = getResources().getStringArray(R.array.planets_array);
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.left_drawer);

    // set a custom shadow that overlays the main content when the drawer opens
    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    // set up the drawer's list view with items and click listener
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, mPlanetTitles));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

    // enable ActionBar app icon to behave as action to toggle nav drawer
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);

    // ActionBarDrawerToggle ties together the the proper interactions
    // between the sliding drawer and the action bar app icon
    mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            R.drawable.ic_drawer,  /* nav drawer image to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description for accessibility */
            R.string.drawer_close  /* "close drawer" description for accessibility */
            ) {
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }

        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mDrawerTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);

    // and now setup the viewpager
    mViewPager = (ViewPager)findViewById(R.id.view_pager);
    mViewPager.setAdapter(new ContentPagerAdapter(getSupportFragmentManager()));

    // sets up the lhs and rhs fragments
    if (savedInstanceState == null) {
        selectItem(0);
    }

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main, menu);
    return super.onCreateOptionsMenu(menu);
}

/* Called whenever we call invalidateOptionsMenu() */
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    // If the nav drawer is open, hide action items related to the content view
    boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
    menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
    return super.onPrepareOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
     // The action bar home/up action should open or close the drawer.
     // ActionBarDrawerToggle will take care of this.
    if (mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }
    // Handle action buttons
    switch(item.getItemId()) {
    case R.id.action_websearch:
        // create intent to perform web search for this planet
        Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
        intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
        // catch event that there's no activity to handle intent
        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);
        } else {
            Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
        }
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        selectItem(position);
    }
}

private void selectItem(int position) {
    // update the main content by replacing fragments
    // create the lhs and rhs fragments
    Fragment lhsFragment = new PlaceHolderFragment();
    Bundle args = new Bundle();
    args.putString(PlaceHolderFragment.FRAGMENT_TEXT_KEY, mPlanetTitles[position]);
    lhsFragment.setArguments(args);

    Fragment rhsFragment = new PlaceHolderFragment();
    args = new Bundle();
    args.putString(PlaceHolderFragment.FRAGMENT_TEXT_KEY, mPlanetTitles[position]);
    rhsFragment.setArguments(args);

    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction ft = fragmentManager.beginTransaction().replace(R.id.lhs_fragment, lhsFragment);
    ft.replace(R.id.rhs_fragment, rhsFragment);
    ft.commit();

    // update selected item and title, then close the drawer
    mDrawerList.setItemChecked(position, true);
    setTitle(mPlanetTitles[position]);
    mDrawerLayout.closeDrawer(mDrawerList);

    // and smooth scroll the viewpager
    mViewPager.setCurrentItem(position, true);
}

@Override
public void setTitle(CharSequence title) {
    mTitle = title;
    getActionBar().setTitle(mTitle);
}

/**
 * When using the ActionBarDrawerToggle, you must call it during
 * onPostCreate() and onConfigurationChanged()...
 */

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
    mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    // Pass any configuration change to the drawer toggls
    mDrawerToggle.onConfigurationChanged(newConfig);
}

/**
 * Fragment that appears in the "content_frame", shows a planet
 */
public static class PlanetFragment extends Fragment {
    public static final String ARG_PLANET_NUMBER = "planet_number";

    public PlanetFragment() {
        // Empty constructor required for fragment subclasses
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_planet, container, false);
        int i = getArguments().getInt(ARG_PLANET_NUMBER);
        String planet = getResources().getStringArray(R.array.planets_array)[i];

        int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
                        "drawable", getActivity().getPackageName());
        ((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
        getActivity().setTitle(planet);
        return rootView;
    }
}

/**
 * Simple Place Holder Fragment...
 */
public static class PlaceHolderFragment extends Fragment {
    public static final String FRAGMENT_TEXT_KEY = "text_key";

    public PlaceHolderFragment() {
    }

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

        View rootView = inflater.inflate(R.layout.place_holder_layout, container, false);
        String text = getArguments().getString(FRAGMENT_TEXT_KEY);

        ((TextView)rootView.findViewById(R.id.place_holder_text)).setText(text);

        return rootView;
    }        
}

/**
 * FragmentStatePagerAdapter for delivering up the planets for the ViewPAger
 */
private class ContentPagerAdapter extends FragmentStatePagerAdapter {       
    int mCount;

    public ContentPagerAdapter(FragmentManager fm) {
        super(fm);
        mCount = getResources().getStringArray(R.array.planets_array).length;
    }

    @Override
    public Fragment getItem(int position) {

        Log.d("ContentPagerAdapter", "getItem() position: " + position + " called.");

        Fragment fragment = new PlanetFragment();
        Bundle args = new Bundle();
        args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
        fragment.setArguments(args);

        return fragment;
    }

    @Override
    public int getCount() {         
        return mCount;
    }
}
}

主要布局

<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<!-- As the main content view, the view below consumes the entire
     space available using match_parent in both dimensions. -->
<include layout="@layout/content_frames_layout" />

<!-- android:layout_gravity="start" tells DrawerLayout to treat
     this as a sliding drawer on the left side for left-to-right
     languages and on the right side for right-to-left languages.
     The drawer is given a fixed width in dp and extends the full height of
     the container. A solid background is used for contrast
     with the content view. -->
<ListView
    android:id="@+id/left_drawer"
    android:layout_width="240dp"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:choiceMode="singleChoice"
    android:divider="@android:color/transparent"
    android:dividerHeight="0dp"
    android:background="#111"/>

</android.support.v4.widget.DrawerLayout>

和 content_frames_layout

<!-- RelativeLayout holds the various fragments / ViewPager that hold the content -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <!-- Simple left hand side fragment -->
    <FrameLayout 
        android:id="@+id/lhs_fragment"
        android:layout_height="match_parent"
        android:layout_width="0px"
        android:layout_weight="1" />

    <!-- The main view pager -->
    <android.support.v4.view.ViewPager 
        android:id="@+id/view_pager"
        android:layout_height="match_parent"
        android:layout_width="0px"
        android:layout_weight="3" >
    </android.support.v4.view.ViewPager>                

    <!-- simple rhs fragment -->
    <FrameLayout 
        android:id="@+id/rhs_fragment"
        android:layout_height="match_parent"
        android:layout_width="0px"
        android:layout_weight="1" />
</LinearLayout>
4

1 回答 1

0

我得到了这种行为,它让我发疯,直到我发现:

视图寻呼机元素必须具有固定宽度

就我而言,我有这个两个窗格的布局(左侧的菜单,右侧的 viewpager):

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:animateLayoutChanges="true">

<fragment android:name="com.vitasalutis.client.main.ParameterMenuFragment"
    android:id="@+id/parameter_menu_fragment"
    android:layout_weight="1"
    android:layout_width="0dp"
    android:layout_height="match_parent" />

<android.support.v4.view.ViewPager
    android:id="@+id/parameter_pager"
    android:layout_weight="2"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:visibility="gone"
    />

</LinearLayout>

必须将 ViewPager 的宽度更改为:

android:layout_width="600dp"

我的猜测是,如果没有固定宽度,它无法确定布局中适合多少页。我试图覆盖getPageWidth(int)以始终返回 1,但也没有工作......

我不知道是否有更好的方法来做到这一点。同时,我会坚持这个解决方案。

于 2013-10-09T16:53:25.873 回答