Develop Reference

Clear data of fragments in ViewPager with each swipe

#Override
public void onViewDetachedFromWindow(#NonNull FragmentViewHolder holder) {
super.onViewDetachedFromWindow(holder);
}
I have many independent EditText with different id in each fragments of viewpager. For each swipe I want to clear these EditText and make them default.
I can clear text using:
holder.itemview.findViewById(R.id.first).setText("something");
but it won't a clear text.
What should I do?
Edit: whole testing Code:
I prepare a test fragment. When I click button,it changes text in current fragment. When I swipe to second fragment, It should be cleared or changed into its default value at xml.
TestFragment
public class TestFragment extends Fragment {
private TestViewModel mViewModel;
private ViewPager2 mViewPager;
private Button btnTest;
public static TestFragment newInstance() {
return new TestFragment();
}
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.test_fragment, container, false);
btnTest=(Button)view.findViewById(R.id.etTest);
return view;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mViewModel = ViewModelProviders.of(this).get(TestViewModel.class);
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mViewPager = view.findViewById(R.id.myPager);
mViewPager.setSaveFromParentEnabled(false);
mViewPager.setOffscreenPageLimit(1);
mViewPager.setAdapter(new ViewPagerAdapter(getChildFragmentManager(),getLifecycle()));
TabLayout tabLayout = view.findViewById(R.id.tabs);
new TabLayoutMediator(tabLayout, mViewPager,
new TabLayoutMediator.TabConfigurationStrategy() {
#Override
public void onConfigureTab(#NonNull TabLayout.Tab tab, int position) {
tab.setText(((ViewPagerAdapter)(mViewPager.getAdapter())).mFragmentNames[position]);//Sets tabs names as mentioned in ViewPagerAdapter fragmentNames array, this can be implemented in many different ways.
}
}
).attach();
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
Fragment current=((ViewPagerAdapter)(mViewPager.getAdapter())).createFragment(tab.getPosition());//clear data here or below
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}});
btnTest.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int cur=((ViewPagerAdapter)(mViewPager.getAdapter())).getCurrentPos();
switch (cur){
case 0:
Fragment current=((ViewPagerAdapter)(mViewPager.getAdapter())).createFragment(0);
TextView tF= current.getView().findViewById(R.id.first);
tF.setText("Clicked while 1");
break;
case 1:
Fragment current2=((ViewPagerAdapter)(mViewPager.getAdapter())).createFragment(1);
TextView tF2= current2.getView().findViewById(R.id.second);
tF2.setText("Clicked while 2");
break;
}
}
});
}
public class ViewPagerAdapter extends FragmentStateAdapter {
private int currentPos;
private final Fragment[] mFragments = new Fragment[] {
new FirstFragment(),
new SecondFragment(),
};
public final String[] mFragmentNames = new String[] {
"First",
"Second"
};
public ViewPagerAdapter(#NonNull FragmentManager fragmentManager, #NonNull Lifecycle lifecycle) {
super(fragmentManager, lifecycle);
}
#Override
public void onViewDetachedFromWindow(#NonNull FragmentViewHolder holder) {
super.onViewDetachedFromWindow(holder);
if(currentPos!=0){
TextView textView =(TextView)holder.itemView.findViewById(R.id.first);//clear data here or up
}
}
#Override
public int getItemCount() {
return mFragments.length;
}
#Override
public long getItemId(int position) {
this.setCurrentPos(position);
return super.getItemId(position);
}
public int getCurrentPos() {
return currentPos;
}
public void setCurrentPos(int currentPos) {
this.currentPos = currentPos;
}
#NonNull
#Override
public Fragment createFragment(int position) {
return mFragments[position];
}
}}
I can handle on onViewDetachedFromWindow or onTabUnselected. Both can change view.
First Fragment
public class FirstFragment extends Fragment {
private View mLeak;
private TextView tvTest;
public FirstFragment() {
}
public static FirstFragment newInstance(String param1, String param2) {
FirstFragment fragment = new FirstFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mLeak = inflater.inflate(R.layout.fragment_first, container, false);
tvTest=mLeak.findViewById(R.id.first);
return mLeak;
}
#Override
public void onDetach() {
super.onDetach();
mLeak=null;
}}

Approach 1:
Set this line on your viewpager :
viewPager.setOffscreenPageLimit(1);
This will simply refresh each fragment again when it's loaded.
Approach 2:
Create an interface and implement it on each fragment. In your activity/fragment where viewpager is defined, use "addOnPageChangeListener" on viewpager, and when the different page is selected, simply use the interface to get back the fragment instance and call the required methods in the fragment, to clear/change the text.
Code :
//Your Activity
class HomeActivity extends Activity{
...Methods...
public void setUpViewpager(){
//setup your viewpager
viewpager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
#Override
public void onPageSelected(int position) {
ChangeText fragment = (ChangeText) viewpager.getFragment(position);
fragment.changeText();
}
#Override
public void onPageScrollStateChanged(int state) {}
});
}
interface ChangeText{
void changeText();
}
}
//Your fragment
class FirstFragment extends Fragment implements HomeActivity.ChangeText{
...Methods...
public void changeText(){
//change the textview text here
}
}
class SecondFragment extends Fragment implements HomeActivity.ChangeText{
...Methods...
public void changeText(){
//change the textview text here
}
}

How to create a multi-step registration form using viewpager and multiple fragments?

I want to create a multi-step registration form in my android app. I wish to use the viewpager with multiple fragments and each fragment being a step in a registration.
At the end, I want to submit all the data submitted in each fragment using an activity to a mysql database. Can I get a small sample code for this?
This is what I have tried so far. I am able to implement a viewpager with multiple fragments. I have created an interface in the StepOne.java Fragment so as to communicate to an activity. But I am not able to retrieve data from these fragments. It throws a null-pointer exception on line 52.
Here is my code:
SliderActivity.java:
public class SliderActivity extends AppCompatActivity {
ViewPager viewPager;
EditText edName,edPassword, edConfPass;
TextView tvShowAll;
ViewPagerAdapter mPagerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_slider);
viewPager = findViewById(R.id.view_pager);
mPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mPagerAdapter);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
}
public void selectIndex(int newIndex) {
viewPager.setCurrentItem(newIndex);
}
#Override
public void onBackPressed() {
int currentPosition = viewPager.getCurrentItem();
if (currentPosition != 0) {
viewPager.setCurrentItem(viewPager.getCurrentItem()-1);
} else {
super.onBackPressed();
}
}
public class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position)
{
case 0:
return new StepOne();
case 1:
return new StepTwo();
case 2:
return new StepThree();
}
return null;
}
#Override
public int getCount() {
return 3; //three fragments
}
}
}
StepOne.java:
public class StepOne extends Fragment {
Button buttonInFragment1;
EditText edName;
public interface ActivityFragmentCallback {
void onSetName(String name);
}
ActivityFragmentCallback listener;
public StepOne() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(R.layout.fragment_step_one, container, false);
edName = rootView.findViewById(R.id.edName);
buttonInFragment1 = rootView.findViewById(R.id.button_one);
if(buttonInFragment1 != null) {
buttonInFragment1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(getContext(),edName.getText().toString(),Toast.LENGTH_SHORT).show();
if(edName != null) {
listener.onSetName(edName.getText().toString());
}
switch (view.getId()){
case R.id.button_one:
((SliderActivity)getActivity()).selectIndex(1);
break;
}
}
});
}
return rootView;
}
#Override
public void onAttach(Context context){
super.onAttach(context);
try {
listener = (ActivityFragmentCallback)context;
}catch (ClassCastException c){
c.printStackTrace();
}
}
}
MessageActivity.java: Here is where I need all the data submitted from all the fragments
public class MessageActivity extends AppCompatActivity implements StepOne.ActivityFragmentCallback {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_message);
}
#Override
public void onSetName(String name){
// tvShowAll = findViewById(R.id.tvShowAll);
// tvShowAll.setText(name);
Toast.makeText(getApplicationContext(),name, Toast.LENGTH_LONG).show();
}
}

Below is some reference link for step by step registration;
Hope you have help
https://github.com/stepstone-tech/android-material-stepper
https://github.com/baoyachi/StepView?utm_source=android-arsenal.com&utm_medium=referral&utm_campaign=3774

Android - TabLayout, Fragments - which function is run after swipe?

I have implemented in my application tab swiping with ViewPager, Fragments etc. Everything is working fine. But I would like to know which function is run after swiping to next tab? Because I need to refresh some data when user will swipe to next screen.
I have this functions in my activity:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootview = inflater.inflate(R.layout.activity_main_sensors_p, container, false);
return rootview;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
update_data();
display_items();
}

YourFragment extends Fragment {
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (this.isVisible()) {
....
} else {
....
}
}
}

You can try set OnPageChangeListener listener to your ViewPager and do action accrding to the current position in pager adapter:
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
// do action accroding to the viewPager position
}
#Override
public void onPageScrollStateChanged(int state) {
}
});

Call method in child fragment in parent fragment from activity

In my MainActivity class I have view pager with 3 tab fragmentHome class, fragmentHot class and FragmentCategoryclass
Here is fragmentCategory class:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view;
view = inflater.inflate(R.layout.fragmentcategory, container, false);
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.replace(R.id.category_fragment, new TabCategoryFragment());
transaction.commit();
return view;
}
In TabCategoryFragment class, I have grid category news and when click item grid I called:
FragmentTransaction transaction = getFragmentManager().beginTransaction();
Bundle bundle = new Bundle();
bundle.putString("category", arrDataZone.get(position).getZone_name());
bundle.putString("zoneid", arrDataZone.get(position).getZone_id());
ListCategoryFragment myFrag = new ListCategoryFragment();
myFrag.setArguments(bundle);
transaction.replace(R.id.category_fragment, myFrag,"listFramgnet");
transaction.addToBackStack("grid_category");
transaction.commit();
Now I want call method in ListCategoryFragment from MainActivity or call method in ListCategoryFragment from FragmentCategory.
Because I try call method in FragmentCategory from MainACtivity with:
linearPlayer.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
int number=viewPager.getCurrentItem();
Fragment fragment= adapter.getItem(number);
if (number==0) {
((FragmentHome)fragment).playAudioSerVice();
} else if(number==1) {
((FragmentHot)fragment).playAudioSerVice();
} else if( number==2) {
((FragmentNew)fragment).playAudioSerVice();
} else if( number==3) {
((FragmentCategory)fragment).playAudioSerVice();
}
}
});
and it ran. Please give me your idea or code to do it.

You can use Eventbus postSticky to resolve it,you can see the api, eventbus
I wrote a demo to simulate your case.Here is the code.
MainActivity:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main22);
getSupportFragmentManager().beginTransaction().replace(R.id.contaner,new MainActivityFragment()).commit();
EventBus.getDefault().register(this);
}
#Subscribe
public void changeFragment(ChangeFragmentEvent event) {
// get event from MainActivityFragment immediately--->EventBus.getDefault().post(new ChangeFragmentEvent());
getSupportFragmentManager().beginTransaction().replace(R.id.contaner,PlusOneFragment.newInstance()).commit();
}
#Override
protected void onDestroy() {
super.onDestroy();
EventBus.getDefault().unregister(this);
}
}
MainActivityFragment:
public class MainActivityFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_main22, container, false);
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
View button = view.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
EventBus.getDefault().post(new ChangeFragmentEvent());//notify MainActivity change fragment
EventBus.getDefault().postSticky(new MEvent());//send a msg to PlusOneFragment,when it shown
}
});
}
}
PlusOneFragment:
public class PlusOneFragment extends Fragment {
public PlusOneFragment() {
}
public static PlusOneFragment newInstance() {
PlusOneFragment fragment = new PlusOneFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EventBus.getDefault().register(this);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_plus_one, container, false);
return view;
}
#Subscribe(sticky = true)
public void getMEvent(MEvent event){
// get event from MainActivityFragment when PlusOneFragment show --->EventBus.getDefault().postSticky(new MEvent());
Toast.makeText(getActivity(),"Hello,there",Toast.LENGTH_SHORT).show();
}
#Override
public void onDetach() {
super.onDetach();
EventBus.getDefault().unregister(this);
}
}

Is it possible to know which image display in ViewPager?

I have two images. I used ViewPager to display them individually. I want to know which ones is displaying in the screen. Could you help me to solve it? For example, when I scroll the screen, the first image will display and Toast a message such as "This is first image", do same thing for second image. Thanks in advance. This is my code
public class ViewPagerExample extends FragmentActivity{
private MyAdapter mAdapter;
private ViewPager mPager;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
}
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return 2;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
{
return new ImageFragment(R.drawable.image1);
}
case 1:
{
return new ImageFragment(R.drawable.image2);
}
default:
return null;
}
}
}
}
and the ImageFragment class
public class ImageFragment extends Fragment {
private final int imageResourceId;
public ImageFragment(int imageResourceId) {
this.imageResourceId = imageResourceId;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e("Test", "hello");
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.image_layout, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.imageView1);
imageView.setImageResource(imageResourceId);
return view;
}
}

try something like this
mPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int pager_position) {
// show toast here for images
}
#Override
public void onPageScrollStateChanged(int state) {
}
});

You can use these lines of code to detect the image on swipe
ViewPager.SimpleOnPageChangeListener pageChangeListener = new ViewPager.SimpleOnPageChangeListener(){
#Override
public void onPageSelected(int position) {
super.onPageSelected(position);
System.out.println("Positoin is the=="+position);
if(position==0)
{
///on the zero position you can get the image
}
else
{
///on the first position you can get the image
}
}
};

There is a method yourViewpagerObject.getCurrentItem() which returns the position of currently Viewed page of view pager