我正在使用ActionbarSherlock和一个实现LoaderManager.LoaderCallbacks的SherlockListFragment.
在我正在使用的ApplicationActivity onCreate方法中
setContentView(R.layout.application);
设置布局 – 效果很好.
我正在初始化动作栏
ActionBar bar = getSupportActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
bar.setDisplayHomeAsUpEnabled(false);
bar.setDisplayShowTitleEnabled(true);
// users event list
bar.addTab(bar.newTab()
.setTag("event_list")
.setText(getString(R.string.list_events_header))
.setTabListener(new TabListener<EventListFragment>(
this, getString(R.string.list_events_header), EventListFragment.class, null)));
在ApplicationActivity中,我有一个AsyncTask,在初始打开时加载需要几秒钟,并且在手动刷新API时 – 这意味着我需要确保更新上面实例化的片段上的ListView,我在onPostExecute方法,我就是这样做的:
// update the events fragment
EventListFragment fragment = (EventListFragment) getSupportFragmentManager().findFragmentById(R.string.list_events_header);
if(fragment != null) {
// restart the loader for this fragment, refreshing the listview
getSupportLoaderManager().restartLoader(0, null, fragment);
}
这一切都有效
现在,我想放入一个TabsAdapter来获取花哨的滑动选项卡,我已经完成了它的工作,但我提到的关于onPostExecute的最后一部分,不起作用:(
这是我的TabsAdapter:
package com.lateral.app.ui;
import java.util.ArrayList;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import com.actionbarsherlock.app.ActionBar;
import com.actionbarsherlock.app.ActionBar.Tab;
public class APPTabsAdapter extends FragmentPagerAdapter implements
ActionBar.TabListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final ActionBar mActionBar;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
static final class TabInfo {
private final Class<?> clss;
private final Bundle args;
TabInfo(Class<?> _class, Bundle _args) {
clss = _class;
args = _args;
}
}
public APPTabsAdapter(ApplicationActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = activity.getSupportActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public APPTabsAdapter(EventActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = activity.getSupportActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
mActionBar.addTab(tab);
notifyDataSetChanged();
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
}
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
public void onPageScrollStateChanged(int state) {
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
Object tag = tab.getTag();
for (int i = 0; i < mTabs.size(); i++) {
if (mTabs.get(i) == tag) {
mViewPager.setCurrentItem(i);
}
}
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
}
这是我从ApplicationActivity更新的onCreate方法
mViewPager = new ViewPager(this);
mViewPager.setId(R.id.pager);
setContentView(mViewPager);
ActionBar bar = getSupportActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
bar.setDisplayHomeAsUpEnabled(false);
bar.setDisplayShowTitleEnabled(true);
mTabsAdapter = new APPTabsAdapter(this, mViewPager);
// users event list
mTabsAdapter.addTab(bar.newTab()
.setTag("event_list")
.setText(getString(R.string.list_events_header))
.setTabListener(new TabListener<EventListFragment>(
this, getString(R.string.list_events_header), EventListFragment.class, null)), EventListFragment.class, null);
这是我对ApplicationActivity中的onPostExecute方法所做的更新
// update the events fragment
EventListFragment fragment = (EventListFragment) mTabsAdapter.getItem(0);
if(fragment != null) {
// restart the loader for this fragment, refreshing the listview
getSupportLoaderManager().restartLoader(0, null, fragment);
}
基本上,当它试图运行我的onPostExecute代码时
我从片段中的cursorAdapter得到一个NullPointerException但它找到了片段..
编辑 – 请求的代码
public Loader<Cursor> onCreateLoader(int loaderId, Bundle args) {
Log.d(TAG, "onCreateLoader");
return new EventCursorLoader(getActivity());
}
public static final class EventCursorLoader extends SimpleCursorLoader {
Context mContext;
public EventCursorLoader(Context context) {
super(context);
Log.d("EventCursorLoader", "Constructor");
mContext = context;
}
@Override
public Cursor loadInBackground() {
Log.d("EventCursorLoader", "loadInBackground");
EventsDataSource datasource = new EventsDataSource(mContext, ((ApplicationActivity)mContext).getDbHelper());
SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(mContext);
long userId = app_preferences.getLong("authenticated_user_id", 0);
return datasource.getAllEvents(userId);
}
}
最佳答案 试图在这里检索加载器只是错误的想法,因为目的是刷新数据.在做了一些挖掘之后,我发现我可以在我的提供商中使用通知超过1组内容
getContext().getContentResolver().notifyChange(uri, null);
通知它更改和刷新,所有这些代码都可以删除并替换为一行.