Question

目前，我的应用程序有两个（滑动）选项卡形式的碎片。在一个片段上，用户可以向数据库添加信息。在另一个片段上，ListView显示DB表的内容。如果用户添加了一个新的DB-Entry并刷到第二个选项卡，则ListView不会更新，因为我在onCreateView（）方法中完成所有加载。

我已经尝试过使用onResume（）方法并从我的FragmentActivity（在onPageSelected（）方法中）调用Fragment的“update方法”。 onResume（）永远不会被调用。我如果从我的“更新方法”（在我的片段中）调用getActivity（），它总是返回null，但我需要我的数据库连接的活动对象。

My Fragment看起来像这样：

public class ListFragment extends Fragment implements AdapterView.OnItemLongClickListener, OnRefreshListener{
private ListView listView;
private SpeedsArrayAdapter adapter = null;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View table = inflater.inflate(R.layout.fragment_list, container, false);
    listView = (ListView)table.findViewById(R.id.listViewSpeeds);

    MySQLiteHelper mSQLHelper = new MySQLiteHelper(getActivity());
    List <MichealSpeedBean> mSpeeds = mSQLHelper.getAllSpeedEntries();

    adapter = new SpeedsArrayAdapter(getActivity(),
            R.layout.list_item, mSpeeds);
    listView.setAdapter(adapter);

    listView.setOnItemLongClickListener(this);
    return table;
}

@Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int position, long id) {
    MySQLiteHelper mSQLHelper = new MySQLiteHelper(getActivity());
    MichealSpeedBean michealSpeedBean = adapter.getItem(position);
    mSQLHelper.deleteSpeedById(michealSpeedBean.getObjectId());
    adapter.remove(michealSpeedBean);

    Toast.makeText(getActivity(),
            "Entry deleted " + position, Toast.LENGTH_LONG)
            .show();
    return false;
}

@Override
public void onRefresh() {
    //getActivity Returns null here, if called form FragmentyActivity
}

我的Fragment Activity看起来像这样：

public class MainActivity extends FragmentActivity {
ViewPager viewPager;
TabPagerAdapter tabAdapter;
ActionBar actionBar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tabAdapter = new TabPagerAdapter(getSupportFragmentManager());
    viewPager = (ViewPager)findViewById(R.id.pager);
    viewPager.setOnPageChangeListener(
            new ViewPager.SimpleOnPageChangeListener() {
                @Override
                public void onPageSelected(int position) {
                    actionBar = getActionBar();
                    actionBar.setSelectedNavigationItem(position);
                    if (position == 1) {
                        //Here i tried to update my list from outside of my fragment
                        ((OnRefreshListener)tabAdapter.getItem(position)).onRefresh();
                    }
                }
            }
    );
    viewPager.setAdapter(tabAdapter);
    actionBar = getActionBar();
    //Enable Tabs on Action Bar
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    ActionBar.TabListener tabListener = new ActionBar.TabListener(){
        @Override
        public void onTabReselected(android.app.ActionBar.Tab tab,
                                    FragmentTransaction ft) {
        }
        @Override
        public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
            viewPager.setCurrentItem(tab.getPosition());
        }
        @Override
        public void onTabUnselected(android.app.ActionBar.Tab tab,
                                    FragmentTransaction ft) {
        }};
    //Add New Tab
    actionBar.addTab(actionBar.newTab().setText("General").setTabListener(tabListener));
    actionBar.addTab(actionBar.newTab().setText("Speed entries").setTabListener(tabListener));
}

所以问题是我在哪里/如何更新我的表格内容？提前谢谢！

Answer 1

您可以使用以下代码：

public class ListFragment extends Fragment
    @Override
    public void setMenuVisibility(final boolean visible) {
        super.setMenuVisibility(visible);
        if (getActivity() != null )
        {
            if (visible) {
               // update your list, your fragment is visible now
             }
         }
    }

Answer 2

你可以用这个：

listview.invalidateViews（）;

享受！

刷新片段上的ListView内容（数据库条目）

2 个答案: