片段中的已保存实例状态 null android

Question

我正在实施滑动菜单概念。对于片段，我在保存的实例中得到了空值。当我单击任何片段时，它不是没有打开该特定页面。它直接转到 (savedInstanceState == null) 值。请给出任何更好的解决方案。提前致谢。

注意：mDrawerList 值 ::: null

SlideMenuClickListener 的 OnItemClick 不起作用..

 public  class SlidingActivity  extends Activity implements OnClickListener {
private static final String TAG = null;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
 private ActionBarDrawerToggle mDrawerToggle;
Button b_project,b_info,b_activity,b_contact;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sliding_menu);

    navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
    navMenuIcons = getResources()
            .obtainTypedArray(R.array.nav_drawer_icons);

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.list_slidermenu);

    navDrawerItems = new ArrayList<NavDrawerItem>();
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1)));
    navDrawerItems.add(new NavDrawerItem(navMenuTitles[6], navMenuIcons.getResourceId(6, -1)));
    navMenuIcons.recycle();
    mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
    adapter = new NavDrawerListAdapter(getApplicationContext(),
            navDrawerItems);
    mDrawerList.setAdapter(adapter);
    Log.d(TAG, "mDrawerList:)  ::: " + mDrawerList);
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);

    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
            R.drawable.ic_drawer,
            R.string.app_name, 
            R.string.app_name 
    ){
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
            // calling onPrepareOptionsMenu() to show action bar icons
            invalidateOptionsMenu();
        }

        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mDrawerTitle);
            // calling onPrepareOptionsMenu() to hide action bar icons
            invalidateOptionsMenu();
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);
     if (savedInstanceState == null) {
        // on first time display view for first nav item
        displayView(0);
    }
}

/**
 * Slide menu item click listener
 * */
private class SlideMenuClickListener implements
        ListView.OnItemClickListener {
    private final String TAG = null;

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        // display view for selected nav drawer item
        displayView(position);
        Log.d(TAG, "value:)  ::: " + position);
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // toggle nav drawer on selecting action bar app icon/title
    if (mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }
    // Handle action bar actions click
    switch (item.getItemId()) {
    case R.id.action_settings:
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

/***
 * Called when invalidateOptionsMenu() is triggered
 */
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    // if nav drawer is opened, hide the action items
    boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
    menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
    return super.onPrepareOptionsMenu(menu);
}

private void displayView(int position) {
    // update the main content by replacing fragments
    Fragment fragment = null;
    switch (position) {
    case 0:
     fragment = new ProjTypeFragment();
     break;
    case 1:
        fragment = new VideoFragment();
        break;
    case 2:
        fragment = new FloorPlanFragment();
        break;
    case 3:
        fragment = new AmenetiesFragment();
        break;
    case 4:
        fragment = new LocationFragment();
        break;
    case 5:
        fragment = new SiteVisitFragment();
        break;
    case 6:
        fragment = new GeneralFragment();
        break;

    default:
        break;
    }

    if (fragment != null) {
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.frame_container, fragment).commit();
         mDrawerList.setItemChecked(position, true);
        mDrawerList.setSelection(position);
        setTitle(navMenuTitles[position]);
        mDrawerLayout.closeDrawer(mDrawerList);
    } else {
         Log.e("SlidingActivity", "Error in creating fragment");
    }
}


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

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    mDrawerToggle.onConfigurationChanged(newConfig);
}
}

Answer 1

要从包中获取数据，您应该使用以下代码：

if(getArguments()!=null) {
int myInt = getArguments().getInt(key, defaultValue);
}

Answer 2

我认为您的代码没有任何问题。它实际上与 Android 网站上的示例非常相似：http://developer.android.com/training/implementing-navigation/nav-drawer.html。我也使用了类似的代码，效果很好。

我认为问题出在您显示的其他片段中。