问题
I am using navigation drawer in my app,I have fragments like F1,F2 and so on..and in every fragment I am parsing data and display in listview,everything is works fine if I go through my app like F1>F2>F3 and so on..but the issue is if I go from F3 to F2,the data which I had in my F2 fragments is not showing,and display only blank page,what is the issue?Can any one help?
My F1
public class Categriesdrawers extends Fragment{
private ImageView drwr;
private SlidingDrawer sldrwr;
private ProgressDialog pDialog;
JSONArray categorylist=null;
private ListView listview;
private ArrayList<HashMap<String,String>> aList;
private static String INTEREST_ACCEPT_URL = "http:.ashx?action=category";
private static final String INTEREST_ACCEPT="categorylist";
private static final String INTERESTACCEPT_USER_ID="Id";
private static final String INTEREST_ACCEPT_NAME="categoryname";
private CustomAdapterCatagory adapter;
private TextView noacpt;
private ListView catlist;
@SuppressWarnings("deprecation")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v=inflater.inflate(R.layout.tests, container, false);
drwr=(ImageView)v.findViewById(R.id.handle);
sldrwr=(SlidingDrawer)v.findViewById(R.id.bottom);
sldrwr.open();
new LoadAlbums().execute();
sldrwr.setOnDrawerOpenListener(new OnDrawerOpenListener() {
@Override
public void onDrawerOpened() {
new LoadAlbums().execute();
}
});
catlist=(ListView)v.findViewById(R.id.substitute_list);
catlist.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Organization tf = new Organization();
Bundle bundle = new Bundle();
tf.setArguments(bundle);
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.mainContent, tf);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(null);
ft.commit();
}
});
return v;
}
class LoadAlbums extends AsyncTask<String, String, ArrayList<HashMap<String,String>>> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Categriesdrawers.this.getActivity());
pDialog.setMessage("Loading...");
pDialog.setIndeterminate(true);
pDialog.setIndeterminateDrawable(getResources().getDrawable(R.drawable.custom_progress));
pDialog.setCancelable(false);
pDialog.show();
}
protected ArrayList<HashMap<String,String>> doInBackground(String... args) {
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
ArrayList<HashMap<String,String>> data = new ArrayList<HashMap<String, String>>();
String jsonStr = sh.makeServiceCall(INTEREST_ACCEPT_URL, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
categorylist = jsonObj.getJSONArray(INTEREST_ACCEPT);
for (int i = 0; i < categorylist.length(); i++) {
JSONObject c = categorylist.getJSONObject(i);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(INTERESTACCEPT_USER_ID, c.getString(INTERESTACCEPT_USER_ID));
map.put(INTEREST_ACCEPT_NAME,c.getString(INTEREST_ACCEPT_NAME));
// adding HashList to ArrayList
data.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return data;
}
protected void onPostExecute(ArrayList<HashMap<String,String>> result) {
super.onPostExecute(result);
// dismiss the dialog after getting all albums
if (pDialog.isShowing())
pDialog.dismiss();
// updating UI from Background Thread
if(aList == null){
aList = new ArrayList<HashMap<String, String>>();
aList.addAll(result);
adapter = new CustomAdapterCatagory(getActivity(),result);
catlist.setAdapter(adapter);
}else{
aList.addAll(result);
adapter.notifyDataSetChanged();
}
}
}
MainActivity
public class MainActivity extends Activity {
ListView mDrawerList;
RelativeLayout mDrawerPane;
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private CharSequence mTitle;
ArrayList<NavItem> mNavItems = new ArrayList<NavItem>();
private CharSequence mDrawerTitle;
ActionBar actionBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
actionBar=getActionBar();
actionBar.setBackgroundDrawable(new ColorDrawable(Color.argb(255, 235, 139, 36)));
mTitle = mDrawerTitle = getTitle();
mNavItems.add(new NavItem("All Post", R.drawable.allpost));
mNavItems.add(new NavItem("Categories", R.drawable.allpost));
mNavItems.add(new NavItem("All Bloggers", R.drawable.allpost));
mNavItems.add(new NavItem("About Us", R.drawable.about));
mNavItems.add(new NavItem("Rate US", R.drawable.rates));
// DrawerLayout
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
// Populate the Navigtion Drawer with options
mDrawerPane = (RelativeLayout) findViewById(R.id.drawerPane);
mDrawerList = (ListView) findViewById(R.id.navList);
DrawerListAdapter adapter = new DrawerListAdapter(this, mNavItems);
mDrawerList.setAdapter(adapter);
mDrawerList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position,
long arg3) {
selectItemFromDrawer(position);
}
});
getActionBar().setDisplayHomeAsUpEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_view, //nav menu toggle icon
R.string.app_name, // nav drawer open - description for accessibility
R.string.app_name // nav drawer close - description for accessibility
) {
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)
{
selectItemFromDrawer(0);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
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);
}
}
private void selectItemFromDrawer(int position) {
Fragment fragment=null;
switch (position) {
case 0:
fragment=new AllPost();
break;
case 1:
fragment=new Categriesdrawers();
break;
case 2:
fragment=new AllBloggerList();
break;
/*case 3:
fragment=new Aboutus();
break;
*/
default:
break;
}
if(fragment!=null)
{
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.mainContent, fragment)
.commit();
mDrawerList.setItemChecked(position, true);
setTitle(mNavItems.get(position).mTitle);
mDrawerLayout.closeDrawer(mDrawerPane);
}
/*Fragment fragment = new PreferencesFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.mainContent, fragment)
.commit();
mDrawerList.setItemChecked(position, true);
setTitle(mNavItems.get(position).mTitle);
// Close the drawer
mDrawerLayout.closeDrawer(mDrawerPane);*/
}
class NavItem {
String mTitle;
String mSubtitle;
int mIcon;
public NavItem(String title, int icon) {
mTitle = title;
mIcon = icon;
}
}
class DrawerListAdapter extends BaseAdapter {
Context mContext;
ArrayList<NavItem> mNavItems;
public DrawerListAdapter(Context context, ArrayList<NavItem> navItems) {
mContext = context;
mNavItems = navItems;
}
@Override
public int getCount() {
return mNavItems.size();
}
@Override
public Object getItem(int position) {
return mNavItems.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.drawer_item, null);
}
else {
view = convertView;
}
TextView titleView = (TextView) view.findViewById(R.id.title);
ImageView iconView = (ImageView) view.findViewById(R.id.icon);
titleView.setText( mNavItems.get(position).mTitle );
iconView.setImageResource(mNavItems.get(position).mIcon);
return view;
}
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
// TODO Auto-generated method stub
super.onConfigurationChanged(newConfig);
mDrawerToggle.onConfigurationChanged(newConfig);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
@Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
}
回答1:
Please call addToBackStack(null) when you perform fragment transaction.
fragmentManager.beginTransaction()
.replace(R.id.mainContent, fragment)
.addToBackStack(null)
.commit();
回答2:
Please update your OnCreateView() as below:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (view != null) {
if (view.getParent() != null) {
((ViewGroup)view.getParent()).removeView(view);
}
return view;
}
View v=inflater.inflate(R.layout.tests, container, false);
I hope this helps
来源：https://stackoverflow.com/questions/32132623/onback-pressed-data-not-showing-in-fragments