Develop Reference

problem with removing previous view in a fragment

i have created a fragment in android that contain 2 functions, the startview() is called at the beginning when the fragment is called, then when user click a button childfragment() is called. and at that point it should have remove the view from the startview() and then replacing it with the newview from childfragment(), and thats what i thought it would do. But instead it did not remove the old view and place the newview on top of the old view. even thought i already place mContainer.removeAllViews(); it did not remove the old view. what am i missing? please help.
here is the code
#SuppressLint("ValidFragment")
public class FragmentSideContent extends android.app.Fragment {
//private OnFragmentInteractionListener mListener;
Context context;
View view,trueview;
ListView listView;
ListAdapter listAdapter;
private LayoutInflater mInflater;
private ViewGroup mContainer;
int[] image = {1,2,3};
String[] titleText = {"one","two","three","one","two","three","one","two","three","one","two","three"};
String[] subTitleText = {"one","two","three","one","two","three","one","two","three","one","two","three"};
public FragmentSideContent(Context context) {
this.context = context;
}
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container,#Nullable Bundle savedInstanceState) {
mInflater = inflater;
mContainer = container;
startview();
return trueview;
}
public void startview(){
view = mInflater.inflate(R.layout.fragment_sidecontent,mContainer,false);
listView = (ListView) view.findViewById(R.id.noteList);
listAdapter = new ListAdapter(context,image,titleText,subTitleText);
listView.setAdapter(listAdapter);
trueview = view;
}
public void childfragment(){
mContainer.removeAllViews();
View newview = mInflater.inflate(R.layout.fragment_sidecontent,mContainer,false);
Fragment childFragment = new FragmentList(context);
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.replace(R.id.child_fragment_container, childFragment).commit();
mContainer.addView(newview);
mContainer.addView(trueview);
trueview = newview;
}
}

I recommend you put in your fragment layout some GroupView for do this.
fragment_layout.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
in yout Fragment.java
View view;
Framelayout fContainer;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_layout, container, false);
return startView();
}
public View startview(){
fContainer = (Framelayout) view.findViewById(R.id.container);
listView = (ListView) view.findViewById(R.id.noteList);
listAdapter = new ListAdapter(context,image,titleText,subTitleText);
listView.setAdapter(listAdapter);
return view;
}
public void childfragment(){
fContainer.removeAllViews();
Fragment childFragment = new FragmentList(context);
FragmentTransaction transaction =
getChildFragmentManager().beginTransaction();
transaction.replace(R.id.container, childFragment).commit();
}
Now in your oncreateview of the other fragment (FragmentList) put the view that you want inflate.
FragmentList.java
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View newview = mInflater.inflate(R.layout.fragment_sidecontent,mContainer,false);
return newview;
}

Send data from Activity to Fragment when fragment is onCreateView

Sorry for my english. I have one activity and in this activity in FragmentPagerAdapter exist 5 fragments. All fragments use one object model for inforation(product name, product image ...).
My activity get data from data base. And then it data send to all fragments. My example Activity:
#BindView(R.id.tabs_sep_prod) TabLayout tabs_sep_prod;
#BindView(R.id.viewpager_sep_prod) ViewPager viewpager_sep_prod;
PrepBaseProdFragment prepBaseProdFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sep_product);
ButterKnife.bind(this);
prepBaseProdFragment = new PrepBaseProdFragment();
// there i have another fragments
// ...
setupViewPager(viewpager_sep_prod);
tabs_sep_prod.setupWithViewPager(viewpager_sep_prod);
}
private void setupViewPager(ViewPager viewPager) {
SepProductActivity.ViewPagerAdapter adapter = new SepProductActivity.ViewPagerAdapter(
adapter.addFrag(prepBaseProdFragment, getString(R.string.sep_prep_base));
// there i have another addFrag
// ...
viewPager.setOffscreenPageLimit(5);
viewPager.setAdapter(adapter);
}
#Override
public void onResume() {
super.onResume();
// this i call method from presenter, it return data in method setData
if(idCat != null && idProd != null)
sepProductPresenter.getSepProd(idCat, idProd);
}
#Override
public void setData(SepProductModel sepProductModel) {
// there i send data to fragment
prepBaseProdFragment.setDataInf(sepProductModel);
// ...
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
my fragment
public class PrepBaseProdFragment extends BaseFragment {
#BindView(R.id.text) TextView text;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_about_prod_prepare_base, parent, false);
ButterKnife.bind(this, view);
Log.e("PrepBaseProdFragment", "PrepBaseProdFragment");
return view;
}
public void setDataInf(SepProductModel sepProductModel) {
text.setText(sepProductModel.getPROPERTY_PR_SUBSTRPREP_UA_VALUE().getTEXT());
}
}
My question: when i send data from activity to fragment, my view do not have time to initialize. In fragment line text.setText(sepProductModel.getPROPERTY_PR_SUBSTRPREP_UA_VALUE().getTEXT()); error
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.widget.TextView.setText(java.lang.CharSequence)' on a null
object reference
Please, help me solve my problem. I spend many times for this

You can check if the text view is null save the data in a variable inside the fragment and in onCreateView use the data variable if it is filled and set the textview text.
Something like this:
// Inside the Fragment body
private SepProductModel sepProductModel;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_about_prod_prepare_base, parent, false);
ButterKnife.bind(this, view);
Log.e("PrepBaseProdFragment", "PrepBaseProdFragment");
if(this.sepProductModel != null)
text.setText(this.sepProductModel.getPROPERTY_PR_SUBSTRPREP_UA_VALUE().getTEXT());
return view;
}
public void setDataInf(SepProductModel sepProductModel) {
if(text != null){
// use text
}
else this.sepProductModel=sepProductModel;
}

I can advise you to wait for your data and then show fragments to adapter, moreover all of them use the same model. While you dont have data, you can show progress bar.
When you have needed model, you can create instances of your fragments and set bundle arguments for them. You can use method like this:
public static MyFragment newInstance(MyModel model){
MyFragment fragment = new MyFragment();
Bundle args = new Bundle();
args.putSerializable(KEY, model);//or args.putParcelable(KEY, model);
fragment.setArguments(args);
return fragment;
}
Notice: your model need to implement Serializable or Parcelable to be putted in bundle. You may read about difference here.
Then in your set data method, when you already have your model you can setup your adapter and set it to view pager, but with this approach:
adapter.addFrag(MyFragment.newInstance(model), getString(R.string.sep_prep_base));
It have to help you, ask me if you have some questions.

How To Set Default Layout in Android

I have a two layouts that scroll back and forth in an Activity. When I press the home button, it returns to the first layout. What I want to do is set the "home" layout to be the second layout i.e. when i press the home button I want it to return to the second screen and not the first. I am having trouble doing this, if anyone could help me I would be very grateful. I didn't include the XML files they have nothing important.
Launcher.java
public class Launcher extends FragmentActivity {
ViewPager viewpager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_launcher)
viewpager = (ViewPager) findViewById(R.id.pager);
PagerAdapter adapter = new PagerAdapter(getSupportFragmentManager());
viewpager.setAdapter(adapter);
}
}
PagerAdapter.java
public class PagerAdapter extends FragmentPagerAdapter {
public PagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int arg0) {
switch (arg0) {
case 0:
return new Fragment1();
case 1:
return new Fragment2();
default:
break;
}
return null;
}
#Override
public int getCount() {
return 2;
}
}
Fragment1.java
public class Fragment1 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_apps,container,false);
}
}
Fragment2.java
public class Fragment2 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_homescreen,container,false);
}
}

If you are using PagerAdapter then use this line to set your default layoutmViewPager.setCurrentItem(1); this will set your 2nd layout as default, layout number starts from 0,1,2,...
Hope this thing help you out.

In this link Set default page for ViewPager in Android, i feel it is the same problem. Maybe it can help you.

Working with fragment class

Hello i want to working with fragment class.
in this code what to write???
in the myDbHelper = new DataBaseHelper(???????);
public class Tozihat extends Fragment{
DataBaseHelper myDbHelper;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_tozihat, container, false);
myDbHelper = new DataBaseHelper();
return view;
}
}

Use getActivity(); as Context if it is Fragment
myDbHelper = new DataBaseHelper(getActivity());

You need Activity's Context. So in Fragment you have to get is using getActivity().
So pass it as follows
myDbHelper = new DataBaseHelper(getActivity());

How can I change the fragment's content on slide in ViewPager?

I have implemented THIS in my activity and it works perfectly fine, but I would like to change the content of my fragment every time when the user slides a finger on the screen. Now it shows the same text not considering the slide(left to right or right to left). How can I handle it? I know that I'm missing an extremely small part here, but I'm not able to understand what is going on. Where should I add the listener and handle the actions?
Here is what I have so far:
public class ViewrerAct extends FragmentActivity {
private static final int NUM_PAGES = 5;
private ViewPager mPager;
private PagerAdapter mPagerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_screen_slide);
// Instantiate a ViewPager and a PagerAdapter.
mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.bulgarian_sayings, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(
R.layout.fragment_viewer, container, false);
return rootView;
}
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
System.out.println("inside!");
return new ScreenSlidePageFragment();
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
AND
public class ScreenSlidePageFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ViewGroup rootView = (ViewGroup) inflater.inflate(
R.layout.fragment_viewer, container, false);
return rootView;
}
}

You should post the code for ScreenSlidPagerAdapter.
Nevertheless, you need to override setPrimaryItem method of pager adapter that gets called every time you slid the pager and change the displayed page.
for ex:
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
super.setPrimaryItem(container, position, object);
currentPage = position;
}
You can store your Strings in array and pass it to adapter and inside adapter you can change the content of the fragment with respect to the selected position.
Post pager adapter as well if want more appropriate example.
In your case, you can simply pass string array, assuming you just want different test to be displayed, to adapter for ex:
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
String[] displayText;
public ScreenSlidePagerAdapter(FragmentManager fm,String[] displayText) {
super(fm);
this.displayText=displayText;
}
#Override
public Fragment getItem(int position) {
System.out.println("inside!");
ScreenSlidePageFragment fragment = new ScreenSlidePageFragment();
fragment.setText(displayTest[position]);
return fragment;
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
And your Fragment class would change to:
public class ScreenSlidePageFragment extends Fragment {
private String text;
public void setText(String text){
this.text=text;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ViewGroup rootView = (ViewGroup) inflater.inflate(
R.layout.fragment_viewer, container, false);
((TextView)rootView.findViewById(textViewId)).setText(Text);
return rootView;
}
}