Java – Android – Interface and inner classes

I’m new to Android programming and am figuring out how to solve this problem. I have a fragment that hosts internal tabs, one of which is ListFragment. On the tabhost fragment, I have a button that calls DialogFragment. When I click “is” on that DialogFragment, I need to refresh the ListFragment (if it is currently in the Active state) to display the items added to the list.

What is the best way to fix this? I was thinking I should put an interface on the DialogFragment, implement the listener on the activity, and then call refresh in the ListFragment. I need to be able to pull the tags of a ListFragment to determine if it’s in the Active state, but I’m not sure how to do that.

I only started learning programming a few months ago and this is my first post on this site. I searched for this answer but couldn’t find anything. I apologize if my method or format is wrong. Thanks for any tips, thanks.

Label fragment :

public class Items extends Fragment implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener, View.OnClickListener {
    MyPageAdapter pageAdapter;
    private ViewPager mViewPager;
    private TabHost mTabHost;

static final String ARG_ID = "id";
    static final String name = "name";
    long id;
    String itemName;

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,  Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tab_test);
        Bundle args = getArguments();
        long id = args.getLong(ARG_ID);
        String itemName = args.getString(name);

View v = inflater.inflate(R.layout.item_tab, container, false);
        mViewPager = (ViewPager) v.findViewById(R.id.pager);

 Tab Initialization
        initialiseTabHost
        mTabHost = (TabHost) v.findViewById(android. R.id.tabhost);
        mTabHost.setup();

 TODO Put here your Tabs
        List<Fragment> fragments = getFragments();
        FragmentActivity context = getActivity();

this. AddTab(context, this.mTabHost, this.mTabHost.newTabSpec("ItemList").setIndicator("ItemList"));

mTabHost.setOnTabChangedListener(this);

 Fragments and ViewPager Initialization

pageAdapter = new MyPageAdapter(getChildFragmentManager(), fragments);
        mViewPager.setAdapter(pageAdapter);
        mViewPager.setOnPageChangeListener(this);

if (savedInstanceState == null) {

}else {
            int pos = savedInstanceState.getInt("tab");
            mTabHost.setCurrentTab(pos);
        }

Button addItemButton = (Button) v.findViewById(R.id.addItem);
        addItemButton.setOnClickListener(this);

return v;
    }

public void onClick(View view) {
        switch (view.getId()) {
            case R.id.addItem:
                DialogFragment addItem = new AddItemDialogFragment();
                Bundle itemArgs = getArguments();
                addItem.setArguments(itemArgs);
                addItem.show(getChildFragmentManager(), "addItem");
                Toast.makeText(getActivity(), "Adding Item", Toast.LENGTH_LONG).show();
                break;
        }
    }

 Method to add a TabHost
    private static void AddTab(FragmentActivity activity, TabHost tabHost, FragmentTabHost.TabSpec tabSpec) {

tabSpec.setContent(new MyTabFactory(activity));
        tabHost.addTab(tabSpec);
    }

 Manages the Tab changes, synchronizing it with Pages
    public void onTabChanged(String tag) {
        int pos = this.mTabHost.getCurrentTab();
        this.mViewPager.setCurrentItem(pos);
    }

@Override
    public void onPageScrollStateChanged(int arg0) {
    }

 Manages the Page changes, synchronizing it with Tabs
    @Override
    public void onPageScrolled(int arg0, float arg1, int arg2) {
        int pos = this.mViewPager.getCurrentItem();
        this.mTabHost.setCurrentTab(pos);
    }

@Override
    public void onPageSelected(int arg0) {
    }

private List<Fragment> getFragments(){
        List<Fragment> fList = new ArrayList<Fragment>();

 TODO Put here your Fragments

Bundle args = getArguments();
        long id = args.getLong("val");

ItemList f1 = ItemList.newinstance(id);
        fList.add(f1);

return fList;
    }

public class MyPageAdapter extends FragmentStatePagerAdapter {
        private List<Fragment> fragments;

public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
            super(fm);
            this.fragments = fragments;
        }

@Override
        public Fragment getItem(int position) {
            return this.fragments.get(position);
        }

@Override
        public int getCount() {
            return this.fragments.size();
        }

}

}

ListFragment

:

public class ItemList extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {

String DATABASE_TABLE;
    String Query;
    String Order;
    String name;
    MainActivity home;

View view;
    public static MyListAdapter mAdapter;
    private static Cursor c;

static ItemList newinstance(long rowId) {
        ItemList itemList = new ItemList();
         Supply val input as an argument.
        Bundle args = new Bundle();
        args.putLong("val", rowId);
        args.putString("name", itemName);
        itemList.setArguments(args);
        return itemList;
    }

public void onActivityCreated(Bundle savedInstanceState) {

super.onActivityCreated(savedInstanceState);
        Bundle args = getArguments();
        int itemId= (int) args.getLong("val");

mAdapter = new MyListAdapter(getActivity(), R.layout.list_row, c, from, to);

setListAdapter(mAdapter);
        setListShown(false);

getLoaderManager().initLoader(itemId, null, this);
    }

public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
        }

public Loader<Cursor> onCreateLoader(int id, Bundle args) {

 View progressBar = getView().findViewById(R.id.progressbar_loading);
             progressBar.setVisibility(View.VISIBLE);

return new RawCursorLoader(getActivity(), Query + Order);
        }

 Called when a previously created loader has finished loading
        public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
            View progressBar = getView().findViewById(R.id.progressbar_loading);
             progressBar.setVisibility(View.GONE);
             Swap the new cursor in.  (The framework will take care of closing the
             old cursor once we return.)
            mAdapter.swapCursor(data);

if (isResumed()) {
                setListShown(true);
            } else {
                setListShownNoAnimation(true);
            }
        }

 Called when a previously created loader is reset, making the data unavailable
        public void onLoaderReset(Loader<Cursor> loader) {
             This is called when the last Cursor provided to onLoadFinished()
             above is about to be closed.  We need to make sure we are no
             longer using it.
            mAdapter.swapCursor(null);
        }

}

Dialog box:

public class AddItemDialogFragment extends DialogFragment {   

UpdateItemListener mListener;

public interface UpdateItemsListener {
    public void onItemAdded();
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);

 This makes sure that the container activity has implemented
     the callback interface. If not, it throws an exception
    try {
        mListener = (UpdateItemListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement UpdateItemListener");
    }
}

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {

 Use the Builder class for convenient dialog construction
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setMessage("Add " + itemName + "?")
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    postItem(ItemId);
                    mListener.onItemAdded();
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                     User cancelled the dialog
                }

});
     Create the AlertDialog object and return it
    return builder.create();
}
}

I was able to figure out that my brain was only temporarily stuck.

The first problem is that the FragmentStatePagerAdapter I use does not set tags when instantiating a fragment. I set it to this because there was a problem with the FragmentPagerAdapter and another thread suggested extending the class instead. I was able to get it to work with the FragmentPagerAdapter that sets the label. Then I call getTag() during the onAttach() method of the ItemList fragment and set the variable on the activity. Then, when adding items, I have an interface on the AddItemDialogFragment and a listener on the activity. Then the listener calls:

    ItemList itemList= (ItemList)
            getSupportFragmentManager().findFragmentByTag("Items")
            .getChildFragmentManager().findFragmentByTag("itemListTag");
if(itemList != null) {
    itemList.listChange();
}