Develop Reference

Not getting current selected Tab position in android tablayout

I am creating a Tab based application where the user can create tabs by clicking a button and can delete the tabs by clicking another button. I implemented this using Tab layout, Fragments and Viewpager.
I am able to get the current tab position when new tab is created by the function setuptablyout function. But when i clicked another tab ie moving to other tabs I am not able to toast the position.
I found that using tabLayout.addOnTabSelectedListener I can get the position, while that doesn't work here.
my Activity Code is:
public class MainActivity extends AppCompatActivity{
TextView textView;
private TabLayout tabLayout;
public static ViewPager viewPager;
public static ViewPagerAdapter adapter;
private ImageView add;
int selectedTabPosition;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = (ViewPager)findViewById(R.id.my_viewpager);
tabLayout = (TabLayout) findViewById(R.id.my_tab_layout);
add= (ImageView) findViewById(R.id.imageButtonAdd1);
adapter = new ViewPagerAdapter(getSupportFragmentManager(), MainActivity.this, viewPager, tabLayout);
viewPager.setAdapter(adapter);
createFirstFragment("POS "+adapter.getCount());
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
Toast.makeText(getApplicationContext(),"Pos onTabSelected: "+ tabLayout.getSelectedTabPosition(),Toast.LENGTH_SHORT).show();
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(adapter.getCount() > 4){
Toast.makeText(MainActivity.this, "Only 5 Tabs allowed", Toast.LENGTH_SHORT).show();
}
else {
Bundle bundle = new Bundle();
bundle.putString("data", "POS "+adapter.getCount());
FragmentChild fragmentChild = new FragmentChild();
fragmentChild.setArguments(bundle);
adapter.addFrag(fragmentChild, "POS "+adapter.getCount());
adapter.notifyDataSetChanged();
if (adapter.getCount() > 0) tabLayout.setupWithViewPager(viewPager);
Log.e("adapter.getCount()",String.valueOf(adapter.getCount()));
viewPager.setCurrentItem(adapter.getCount() - 1);
setupTabLayout();
}
}
});
}
public void createFirstFragment(String pagename) {
Bundle bundle = new Bundle();
bundle.putString("data", pagename);
FragmentChild fragmentChild = new FragmentChild();
fragmentChild.setArguments(bundle);
adapter.addFrag(fragmentChild, pagename);
adapter.notifyDataSetChanged();
if (adapter.getCount() > 0) tabLayout.setupWithViewPager(viewPager);
Log.e("adapter.getCount()",String.valueOf(adapter.getCount()));
viewPager.setCurrentItem(adapter.getCount() - 1);
setupTabLayout();
}
public void setupTabLayout() {
selectedTabPosition = viewPager.getCurrentItem();
Toast.makeText(MainActivity.this, "selectedTabPosition --> "+selectedTabPosition, Toast.LENGTH_SHORT).show();
for (int i = 0; i < tabLayout.getTabCount(); i++) {
tabLayout.getTabAt(i).setCustomView(adapter.getTabView(i));
}
}
}
ViewPager class:
public class ViewPagerAdapter extends FragmentPagerAdapter {
private final ArrayList<Fragment> mFragmentList = new ArrayList<>();
private final ArrayList<String> mFragmentTitleList = new ArrayList<>();
Context context;
ViewPager viewPager;
TabLayout tabLayout;
int selectedTabPosition;
PreferenceHelper prefs;
private Map<Integer, String> mFragmentTags;
private FragmentManager mFragmentManager;
private boolean doNotifyDataSetChangedOnce = false;
public ViewPagerAdapter(FragmentManager manager, Context context, ViewPager viewPager,
TabLayout tabLayout) {
super(manager);
this.context = context;
this.viewPager = viewPager;
this.tabLayout = tabLayout;
mFragmentTags = new HashMap<Integer, String>();
prefs = new PreferenceHelper(context);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
if (doNotifyDataSetChangedOnce) {
doNotifyDataSetChangedOnce = false;
notifyDataSetChanged();
}
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
public void removeFrag(int position) {
removeTab(position);
Fragment fragment = mFragmentList.get(position);
mFragmentList.remove(fragment);
mFragmentTitleList.remove(position);
//destroyFragmentView(viewPager, position, fragment);
notifyDataSetChanged();
Log.e("getCount()", String.valueOf(getCount()));
if (getCount() > 0)
tabLayout.setupWithViewPager(viewPager);
setupTabLayout();
}
public View getTabView(final int position) {
View view = LayoutInflater.from(context).inflate(R.layout.custom_tab_item, null);
TextView tabItemName = (TextView) view.findViewById(R.id.textViewTabItemName);
ImageView tabItemAvatar =
(ImageView) view.findViewById(R.id.imageViewTabItemAvatar);
ImageButton remove = (ImageButton) view.findViewById(R.id.imageButtonRemove);
if(getCount() == 1){
remove.setVisibility(View.INVISIBLE);
}
else{
remove.setVisibility(View.VISIBLE);
}
remove.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d("Remove", "Remove");
if(getCount() != 1){
removeFrag(position);
}
else{
// Toast.makeText("Atleast One Tab is requied")
}
}
});
tabItemName.setText(mFragmentTitleList.get(position));
tabItemName.setTextColor(context.getResources().getColor(android.R.color.background_light));
tabItemAvatar.setImageResource(R.drawable.boy);
return view;
}
public void setupTabLayout() {
selectedTabPosition = viewPager.getCurrentItem();
Toast.makeText(context, "selectedTabPosition --> "+selectedTabPosition, Toast.LENGTH_SHORT).show();
for (int i = 0; i < tabLayout.getTabCount(); i++) {
tabLayout.getTabAt(i).setCustomView(getTabView(i));
}
}
public void removeTab(int position) {
if (tabLayout.getChildCount() > 0 && tabLayout!=null) {
tabLayout.removeTabAt(position);
prefs.remove("POS"+position);
}
}
/*#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
if (mCurrentFragment != object) {
mCurrentFragment = (Fragment) object;
}
super.setPrimaryItem(container, position, object);
}*/
#Override
public Object instantiateItem(ViewGroup container, int position) {
Object object = super.instantiateItem(container, position);
if (object instanceof Fragment) {
Fragment fragment = (Fragment) object;
String tag = fragment.getTag();
mFragmentTags.put(position, tag);
}
return object;
}
public Fragment getFragment(int position) {
Fragment fragment = null;
String tag = mFragmentTags.get(position);
if (tag != null) {
fragment = mFragmentManager.findFragmentByTag(tag);
}
return fragment;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
I am getting this weird behaviour that whenever I create new tabs the onTabSelected functions are calling multiple time that even when I create 3rd tab onTabslected toast shows Pos onTabSelected: 0,1 and not the just 2nd position which is supposed to be the 2nd position. What can I do to solve this?
My intention is to get some unique tab id so that I can identify each tab separately

you just create the newInstance constructor for creating fragment with arguments
in your FragmentChild
public static FragmentChild newInstance(int page, String title) {
FragmentChild fragmentChild = new FragmentChild ();
Bundle args = new Bundle();
args.putInt("someInt", page);
args.putString("someTitle", title);
fragmentChild.setArguments(args);
return fragmentChild;
}
// Store instance variables based on arguments passed
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
page = getArguments().getInt("someInt", 0);
title = getArguments().getString("someTitle");
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_first, container, false);
TextView tvLabel = (TextView) view.findViewById(R.id.tvLabel);
tvLabel.setText(page + " -- " + title);
return view;
}
And then after in adapter class change this.
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
to
#Override
public Fragment getItem(int position) {
return FragmentChild.newInstance(position, "Page # 1");
}
I have not tested this code but, I think this code will help you to get your unique tab id..
test this code and let me know if it works

Refresh a fragment inside a viewpager which is inside a fragment

I have an activity which consists of three fragments. In one of these fragments I have a viewpager that consists of three other fragments. I call getChildFragmentManager() inside fragment that has viewpager in it. I have searched SO and read almost every answer that are related to this topic for example: this and this and one that seemed most useful was this but could not solve my problem. I think if i can just return POSITION_NONE for getItemPosition(Object object) in FragmentStatePagerAdapter and call notifyDataSetChanged() will solve my problem but every time I do this my app crashes with this error:
java.lang.IllegalStateException: FragmentManager is already executing
transactions!!!
and I mentioned that I am using getChildFragmentManager() inside my fragment.
Anyone thinks of any solution to this problem?
this is the parent fragment:
public class WordDetailFragment extends Fragment {
#BindView(R.id.word_parts_tab_layout)
TabLayout mTabLayout;
#BindView(R.id.word_part_view_pager)
ViewPager mViewPager;
private WordPagerAdapter mPagerAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_detail, container, false);
ButterKnife.bind(this, view);
mPagerAdapter = new WordPagerAdapter(getChildFragmentManager(), getActivity());
mViewPager.setAdapter(mPagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
return view;
}
public void notifyTranslateChanged() {
mViewPager.getAdapter().notifyDataSetChanged();
}
}
this is the code for adapter
public class WordPagerAdapter extends FragmentStatePagerAdapter {
final int PAGE_COUNT = 3;
private String[] tabTitles = new String[]{"Definition", "Example", "Col & fam"};
private Context context;
public WordPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
Fragment fragment;
switch (position) {
case 0:
fragment = new WordDefinitionFragment();
break;
case 1:
fragment = new WordExampleFragment();
break;
case 2:
fragment = new WordColFamFragment();
break;
default: fragment = new WordDefinitionFragment();
}
return fragment;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}
One of the fragments in viewpager
public class WordDefinitionFragment extends Fragment {
#BindView(R.id.show_translate_switch)
Switch mShowTranslateSwitch;
private List<WordInfo> mWordInfoList;
private List<Definition> mDefinitionList;
private boolean mShowTranslation;
private View mView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.fragment_word_definition, container, false);
ButterKnife.bind(this, mView);
mShowTranslation = SharedPrefHelper.getBooleanInfo(getActivity(), getString(R.string.show_translate_key));
mShowTranslateSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
if (getActivity() != null)
((WordActivity) getActivity()).changeTranslateMode(b);
showTranslation(b);
}
});
return mView;
}
}
and my activity. U have just included the parts that i felt are needed here.
public class WordActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceSate) {
super.onCreate(savedInstanceSate);
setContentView(R.layout.activity_word);
}
public void changeTranslateMode(boolean show) {
SharedPrefHelper.setBooleanInfo(this, getString(R.string.show_translate_ke)y, show);
((WordDetailFragment)mWordDetailFragment).notifyTranslateChanged();
}
}
and my logcat error is

After many searches I could figure out a way which is not very smart but for the time being has solved my problem.
First of all I used the class FixedFragmentStatePagerAdapter from this post. I also had to remove the part in which the fragment bundle is restored because it caches fragment variables and views.
public abstract class FixedFragmentStatePagerAdapter extends PagerAdapter {
private static final String TAG = "PagerAdapter";
private static final boolean DEBUG = false;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<>();
private ArrayList<String> mSavedFragmentTags = new ArrayList<>();
private ArrayList<Fragment> mFragments = new ArrayList<>();
private Fragment mCurrentPrimaryItem = null;
public FixedFragmentStatePagerAdapter(FragmentManager fm) {
mFragmentManager = fm;
}
/**
* Return the Fragment associated with a specified position.
*/
public abstract Fragment getItem(int position);
public String getTag(int position) {
return null;
}
#Override
public void startUpdate(ViewGroup container) {
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
return f;
}
}
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
Fragment fragment = getItem(position);
String fragmentTag = getTag(position);
if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment + " t=" + fragmentTag);
/* if (mSavedState.size() > position) {
String savedTag = mSavedFragmentTags.get(position);
if (TextUtils.equals(fragmentTag, savedTag)) {
Fragment.SavedState fss = mSavedState.get(position);
if (fss != null) {
fragment.setInitialSavedState(fss);
}
}
}*/
while (mFragments.size() <= position) {
mFragments.add(null);
}
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
mFragments.set(position, fragment);
mCurTransaction.add(container.getId(), fragment, fragmentTag);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
+ " v=" + ((Fragment)object).getView() + " t=" + fragment.getTag());
while (mSavedState.size() <= position) {
mSavedState.add(null);
mSavedFragmentTags.add(null);
}
mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
mSavedFragmentTags.set(position, fragment.getTag());
mFragments.set(position, null);
mCurTransaction.remove(fragment);
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
}
#Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment)object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle state = null;
if (mSavedState.size() > 0) {
state = new Bundle();
Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
mSavedState.toArray(fss);
state.putParcelableArray("states", fss);
state.putStringArrayList("tags", mSavedFragmentTags);
}
for (int i=0; i<mFragments.size(); i++) {
Fragment f = mFragments.get(i);
if (f != null) {
if (state == null) {
state = new Bundle();
}
String key = "f" + i;
mFragmentManager.putFragment(state, key, f);
}
}
return state;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state != null) {
Bundle bundle = (Bundle)state;
bundle.setClassLoader(loader);
Parcelable[] fss = bundle.getParcelableArray("states");
mSavedState.clear();
mFragments.clear();
ArrayList<String> tags = bundle.getStringArrayList("tags");
if (tags != null) {
mSavedFragmentTags = tags;
} else {
mSavedFragmentTags.clear();
}
if (fss != null) {
for (int i=0; i<fss.length; i++) {
mSavedState.add((Fragment.SavedState)fss[i]);
}
}
Iterable<String> keys = bundle.keySet();
for (String key: keys) {
if (key.startsWith("f")) {
int index = Integer.parseInt(key.substring(1));
Fragment f = mFragmentManager.getFragment(bundle, key);
if (f != null) {
while (mFragments.size() <= index) {
mFragments.add(null);
}
f.setMenuVisibility(false);
mFragments.set(index, f);
} else {
Log.w(TAG, "Bad fragment at key " + key);
}
}
}
}
}
}
Then I implemented ViewPager.OnPageChangeListener in the fragment that contains the viewpager. And in the void onPageScrollStateChanged(int state) method I updated the view of my fragments in viewpager.
public class WordDetailFragment extends Fragment implements ViewPager.OnPageChangeListener {
#BindView(R.id.word_parts_tab_layout)
TabLayout mTabLayout;
#BindView(R.id.word_part_view_pager)
ViewPager mViewPager;
private WordPagerAdapter mPagerAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_detail, container, false);
ButterKnife.bind(this, view);
mPagerAdapter = new WordPagerAdapter(getChildFragmentManager(), getActivity());
mViewPager.setAdapter(mPagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
mViewPager.addOnPageChangeListener(this);
return view;
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
Fragment mFragment;
#Override
public void onPageSelected(int position) {
mFragment = mPagerAdapter.getItem(position);
}
#Override
public void onPageScrollStateChanged(int state) {
if (state == ViewPager.SCROLL_STATE_IDLE) {
if (mFragment instanceof WordDefinitionFragment) {
((WordDefinitionFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
if (mFragment instanceof WordExampleFragment) {
((WordExampleFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
if (mFragment instanceof WordColFamFragment) {
((WordColFamFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
}
}
}
And in my fragments, I had a callback interface which was implemented in the activity. And in void setUserVisibleHint(boolean isVisibleToUser) method I updated the UI again because neighbor fragments did not get updated.
public class WordExampleFragment extends Fragment {
#BindView(R.id.example_field_name_id)
TextView mExampleFieldNameTV;
#BindView(R.id.word_tv)
TextView mWordTv;
#BindView(R.id.play_sound_iv)
ImageView mPlaySoundIv;
#BindView(R.id.show_translate_switch)
Switch mShowTranslateSwitch;
private TextView mExample1ContentFaTV;
private List<WordInfo> mWordInfoList;
private List<Example> mExampleList;
private int mWordNumber;
//callback interface
private TranslateModeChangeListener mWordPartFragments;
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mWordPartFragments = (TranslateModeChangeListener) context;
} catch (ClassCastException ex) {
throw new ClassCastException("Must implement WordPartFragments interface");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_example, container, false);
ButterKnife.bind(this, view);
mWordInfoList = WordActivity.sWordInfoList;
mWordNumber = WordActivity.sWordNumber;
mExampleList = mWordInfoList.get(mWordNumber).getExamples();
showTranslation();
mShowTranslateSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
//this method is called from activity=> callback interface
mWordPartFragments.changeTranslateMode(b);
showTranslation();
}
});
return view;
}
//this method is called when viewpager shows this fragment and it is visible to user
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
showTranslation();
}
}
//this methoud updates my UI: shows or hides the translation
public void showTranslation() {
if (isAdded()) {
boolean showTranslation = WordActivity.sTranslationShown;
//Log.e("Ex", "added & shown = " + showTranslation);
mShowTranslateSwitch.setChecked(showTranslation);
mExample1ContentFaTV.setVisibility((showTranslation) ? View.VISIBLE : View.INVISIBLE);
}
}
}

how to call the viewPager adapter from another fragmentClass

I need to implement a fragment replacement in the ViewPager.
After some search, I found this adapter (that seems to work good):
public class ViewPagerAdapter extends FragmentStatePagerAdapter implements ViewPager.OnPageChangeListener
{
private final AppCompatActivity mActivity;
private final TabLayout tabLayout;
private final ViewPager mPager;
private List<TabInfo> mTabs = new LinkedList<TabInfo>();
private int TOTAL_TABS;
private Map<Integer, Stack<TabInfo>> history = new HashMap<Integer, Stack<TabInfo>>();
public ViewPagerAdapter(AppCompatActivity activity, ViewPager pager, TabLayout tabLayout)
{
super(activity.getSupportFragmentManager());
activity.getSupportFragmentManager();
this.mActivity = activity;
this.mPager = pager;
this.tabLayout = tabLayout;
}
public void addTab(final Class fragmentClass, final Bundle args)
{
final TabInfo tabInfo = new TabInfo(fragmentClass, args);
tabLayout.newTab();
tabLayout.setTag(tabInfo);
mTabs.add(tabInfo);
notifyDataSetChanged();
}
#Override
public Fragment getItem(final int position)
{
final TabInfo tabInfo = mTabs.get(position);
return Fragment.instantiate(mActivity, tabInfo.fragmentClass.getName(), tabInfo.args);
}
#Override
public int getItemPosition(final Object object) {
int position = tabLayout.getSelectedTabPosition();
int pos = POSITION_NONE;
if (history.get(position).isEmpty()) {
return POSITION_NONE;
}
for (Stack<TabInfo> stack : history.values()) {
TabInfo c = stack.peek();
if (c.fragmentClass.getName().equals(object.getClass().getName())) {
pos = POSITION_UNCHANGED;
break;
}
}
return pos;
}
#Override
public int getCount() {
return mTabs.size();
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageSelected(int position)
{
}
public void onTabSelected(final FragmentTransaction ft) {
TabInfo tabInfo = (TabInfo) tabLayout.getTag();
for (int i = 0; i < mTabs.size(); i++) {
if (mTabs.get(i).equals(tabInfo)) {
mPager.setCurrentItem(i);
}
}
}
public void onTabUnselected(FragmentTransaction ft) {
}
public void onTabReselected(FragmentTransaction ft) {
}
public void replace(final int position, final Class fragmentClass, final Bundle args)
{
mActivity.getSupportFragmentManager().beginTransaction().addToBackStack(null).commit();
updateTabs(new TabInfo(fragmentClass, args), position);
history.get(position).push(new TabInfo(mTabs.get(position).fragmentClass, mTabs.get(position).args));
notifyDataSetChanged();
}
private void updateTabs(final TabInfo tabInfo, final int position)
{
mTabs.remove(position);
mTabs.add(position, tabInfo);
tabLayout.getTabAt(position).setTag(tabInfo);
}
public void createHistory()
{
int position = 0;
TOTAL_TABS = mTabs.size();
for (TabInfo mTab : mTabs)
{
if (history.get(position) == null)
{
history.put(position, new Stack<TabInfo>());
}
history.get(position).push(new TabInfo(mTab.fragmentClass, mTab.args));
position++;
}
}
public void back()
{
int position = tabLayout.getSelectedTabPosition();
if (!historyIsEmpty(position))
{
if (isLastItemInHistory(position))
{
mActivity.finish();
}
final TabInfo currentTabInfo = getPrevious(position);
mTabs.clear();
for (int i = 0; i < TOTAL_TABS; i++)
{
if (i == position)
{
mTabs.add(new TabInfo(currentTabInfo.fragmentClass, currentTabInfo.args));
}
else
{
TabInfo otherTabInfo = history.get(i).peek();
mTabs.add(new TabInfo(otherTabInfo.fragmentClass, otherTabInfo.args));
}
}
}
notifyDataSetChanged();
}
private boolean historyIsEmpty(final int position)
{
return history == null || history.isEmpty() || history.get(position).isEmpty();
}
private boolean isLastItemInHistory(final int position)
{
return history.get(position).size() == 1;
}
private TabInfo getPrevious(final int position)
{
TabInfo currentTabInfo = history.get(position).pop();
if (!history.get(position).isEmpty()) {
currentTabInfo = history.get(position).peek();
}
return currentTabInfo;
}
private static class TabInfo
{
public Class fragmentClass;
public Bundle args;
public TabInfo(Class fragmentClass, Bundle args)
{
this.fragmentClass = fragmentClass;
this.args = args;
}
public boolean equals(final Object o)
{
return this.fragmentClass.getName().equals(o.getClass().getName());
}
public int hashCode() {
return fragmentClass.getName() != null ? fragmentClass.getName().hashCode() : 0;
}
public String toString() {
return "TabInfo{" +
"fragmentClass=" + fragmentClass +
'}';
}
}
}
and I need to call methods replace() and back() in this adapter.
This is how I call this adapter from WindFragment in setupViewPager() method:
private void setupViewPager(ViewPager viewPager, TabLayout tabLayout)
{
adapter = new ViewPagerAdapter((AppCompatActivity)getActivity(),viewPager,tabLayout);
adapter.addTab(THGSFragment.class,null);
adapter.addTab(FlightPerformanceFragment.class,null);
adapter.addTab(AviationConverterFragment.class,null);
adapter.addTab(SpeedFragment.class,null);
adapter.createHistory();
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
tabLayout.getTabAt(0).setText(getString(R.string.thgs));
tabLayout.getTabAt(1).setText(getString(R.string.tcgs));
tabLayout.getTabAt(2).setText(getString(R.string.wv));
tabLayout.getTabAt(3).setText(getString(R.string.thtas));
}
now I'm in this class:
public class THGSFragment extends Fragment
{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
{
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_thg, container, false);
ImageView button= (ImageView) rootView.findViewById(R.id.calcEAS);
button.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
}
});
return rootView;
}
}
and in the onClick() method I need to call the method replace() from the adapter, but I don't know how.
So, I need to use an interface (that I'm not good to use) ?
Thank you

Recycler View - Custom Checkbox: keeping state while scrolling

I've seen quite a few posts about this "issue" with RecyclerView, but I can't manage to fix it.
Every time I scroll, my custom CheckBoxes (starStyle) keep turning on/off.
I've tried to follow other solutions here on Stack, but none seems to do the job for me.
Just to explain the structure of my app, I've a long list (each item has a StarStyle CheckBox): when I click on an item, the app takes me in the Details Page for that item, where I can set the CheckBox, too. I managed to bind the list's checkbox and the one in the detail page, but I still having this annoying problem.
Here my code for the ListFragment:
public class PetrolStationListFragment extends Fragment {
private RecyclerView mPetrolStationRecyclerView;
private PetrolStationAdapter mAdapter;
private int itemPosition;
private int mLastAdapterClickPosition = -1;
private List<Boolean> mCheckState = new ArrayList<>();
public static boolean toBeCreated;
private static final String ARG_POSITION = "position";
// Design pattern to instantiate a new fragment.
public static PetrolStationListFragment newInstance(int position) {
PetrolStationListFragment fragment = new PetrolStationListFragment();
Bundle args = new Bundle();
args.putInt(ARG_POSITION, position);
fragment.setArguments(args);
return fragment;
}
/********************************************************/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_petrol_station_list, container, false);
mPetrolStationRecyclerView = (RecyclerView) view.findViewById(R.id.petrol_recycler_view);
mPetrolStationRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
#Override
public void onResume() {
super.onResume();
updateUI();
}
private void updateUI() {
PetrolStationDAO petrolStationDAO = PetrolStationDAO.get(getActivity());
List<PetrolStation> petrolStations = petrolStationDAO.getPetrolStations();
if (mAdapter == null || toBeCreated) {
mAdapter = new PetrolStationAdapter(petrolStations);
mPetrolStationRecyclerView.setAdapter(mAdapter);
toBeCreated = false;
} else {
if (mLastAdapterClickPosition < 0) {
mAdapter.setPetrolStations(petrolStations);
mAdapter.notifyDataSetChanged();
} else {
mAdapter.notifyItemChanged(mLastAdapterClickPosition);
mLastAdapterClickPosition = -1;
}
mAdapter.notifyItemChanged(itemPosition);
}
}
private class PetrolStationHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private PetrolStation mPetrolStation;
private TextView mNameTextView;
private TextView mAddressTextView;
private TextView mDistanceTextView;
private CheckBox mCheckBox;
private int mPosition;
public PetrolStationHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
mNameTextView = (TextView) itemView.findViewById(R.id.list_item_station_name_text_view);
mAddressTextView = (TextView) itemView.findViewById(R.id.list_item_station_address_text_view);
mDistanceTextView = (TextView) itemView.findViewById(R.id.list_item_station_distance_text_view);
mCheckBox = (CheckBox) itemView.findViewById(R.id.checkbox);
}
public void bindPetrolStation(PetrolStation petrolStation, int position) {
mPetrolStation = petrolStation;
mNameTextView.setText(mPetrolStation.getName());
mAddressTextView.setText("Via Verdi, 19/A");
mDistanceTextView.setText("300 meters");
mPosition = position;
//mCheckBox.setChecked(mPetrolStation.isFavourite());
mCheckBox.setChecked(mCheckState.get(mPosition));
Log.d("BIND_POSITION", "position: " + mPosition + " / status: " + mCheckState.get(mPosition));
mCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
boolean boxChecked = mPetrolStation.isFavourite();
Log.d("BOX_CHECKED_POSITION", "boxChecked: " + boxChecked);
if (boxChecked) {
mPetrolStation.setFavourite(false);
} else {
mPetrolStation.setFavourite(true);
}
if (boxChecked) {
mCheckState.set(mPosition, false);
} else {
mCheckState.set(mPosition, true);
}
Log.d("CHECK_POSITION", "mCheckState: " + mCheckState);
// TODO: DB connection.
// PetrolStationDAO.get(getActivity()).updateItem(mCrime);
}
});
}
#Override
public void onClick(View v) {
itemPosition = mPetrolStationRecyclerView.getChildAdapterPosition(v);
Intent intent = PetrolStationPagerActivity.newIntent(getActivity(), mPetrolStation.getId());
startActivity(intent);
}
}
private class PetrolStationAdapter extends RecyclerView.Adapter<PetrolStationHolder> {
private List<PetrolStation> mPetrolStations;
public PetrolStationAdapter(List<PetrolStation> petrolStations) {
mPetrolStations = petrolStations;
for (int i = 0; i < mPetrolStations.size(); i++) {
mCheckState.add(false);
}
}
#Override
public PetrolStationHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
View view = layoutInflater.inflate(R.layout.list_item_petrol_station, parent, false);
return new PetrolStationHolder(view);
}
#Override
public void onBindViewHolder(PetrolStationHolder holder, int position) {
PetrolStation petrolStation = mPetrolStations.get(position);
holder.bindPetrolStation(petrolStation, position);
// holder.setIsRecyclable(false);
}
#Override
public int getItemCount() {
return mPetrolStations.size();
}
public void setPetrolStations(List<PetrolStation> petrolStations) {
mPetrolStations = petrolStations;
}
}
}
Here the one for the DetailsFragment:
public class PetrolStationFragment extends Fragment {
private static final String ARG_PETROL_STATION_ID = "petrol_station_id";
private PetrolStation mPetrolStation;
private TextView mInfo;
private CheckBox mCheckBox;
private static TabLayout mTabLayout;
private static ViewPager mViewPager;
private static int intItems = 2;
// Navigation Tab constants.
private static final int SELF_SERVICE_POSITION = 0;
private static final int FULL_SERVICE_POSITION = 1;
// Design pattern to instantiate a new fragment.
public static PetrolStationFragment newInstance(long petrolStationId) {
Bundle args = new Bundle();
args.putLong(ARG_PETROL_STATION_ID, petrolStationId);
PetrolStationFragment fragment = new PetrolStationFragment();
fragment.setArguments(args);
return fragment;
}
/********************************************************/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
long mId = getArguments().getLong(ARG_PETROL_STATION_ID);
mPetrolStation = PetrolStationDAO.get(getActivity()).getPetrolStation(mId);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceStace) {
View view = inflater.inflate(R.layout.fragment_petrol_station, container, false);
mInfo = (TextView) view.findViewById(R.id.petrol_station);
mCheckBox = (CheckBox) view.findViewById(R.id.checkbox);
mInfo.setText(mPetrolStation.getName());
mCheckBox.setChecked(mPetrolStation.isFavourite());
// TODO: to fix.
mCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isFavourite) {
mPetrolStation.setFavourite(isFavourite);
}
});
// Setup Views.
mTabLayout = (TabLayout) view.findViewById(R.id.pager_header);
mViewPager = (ViewPager) view.findViewById(R.id.pager);
// Set an Adapter for the View Pager.
TabPagerAdapter tabPagerAdapter = new TabPagerAdapter(getChildFragmentManager());
mViewPager.setAdapter(tabPagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
mViewPager.setCurrentItem(SELF_SERVICE_POSITION);
mTabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
int flag;
#Override
public void onTabSelected(TabLayout.Tab tab) {
mViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
mInfo.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
#Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
mPetrolStation.setName(charSequence.toString());
}
#Override
public void afterTextChanged(Editable editable) {
}
});
return view;
}
class TabPagerAdapter extends FragmentPagerAdapter {
public TabPagerAdapter(FragmentManager fm) {
super(fm);
}
// Return fragment with respect to position.
#Override
public Fragment getItem(int position) {
Fragment fragment;
switch (position) {
case SELF_SERVICE_POSITION: {
fragment = SelfServiceFragment.newInstance();
return fragment;
}
case FULL_SERVICE_POSITION: {
fragment = FullServiceFragment.newInstance();
return fragment;
}
}
return null;
}
#Override
public int getCount() {
return intItems;
}
// This method returns the title of the tab according to its position.
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case SELF_SERVICE_POSITION: {
String mSelfService = getResources().getString(R.string.self_service);
return mSelfService;
}
case FULL_SERVICE_POSITION: {
String mFullService = getResources().getString(R.string.full_service);
return mFullService;
}
}
return null;
}
}
}
Any hints about how to solve this issue?
Am I missing some kind of check?

Use a List of boolean type to hold the state of the checkbox. By default fill your collection with a false value.
When you select a checkbox change the state of the map using the set method
As you know When you scroll there will be a call to your adapter there you read the value from the map using get and set it to checkbox
List < Boolean > checkstate = new ArrayList < Boolean > ();
// Inside the adapter constructor
for (i = 0; i < itemSize; i++) {
checkstate.add(false);
}
Inside your Viewholder add below Line what it does is whatever the updated value of checkbox will set to your checkbox. Initially all the Items will be false
yourCheckbox.setChecked(checkstate.get(position));
Now inside onCheckedChanged Listener
if (boxchecked) {
checkstate.set(position, true);
} else {
checkstate.set(position, false);
}

How does findFragmentByTag work in a parent Fragment to know which child fragment is currently showing with ViewPagerAdapter?

My MainFragment is like
public class MainTabFragment extends Fragment {
public static int position_child_tab = 0, three_childs_tab_position = 0;
static int count = -1;
int position_tab = 0;
Bundle args;
public static MyTabLayout myTabLayout;
private static MainTabFragment sMainTabFragment;
public static NonSiwpablePager pager;
private Fragment mFragment;
public MainTabFragment() {
// Required empty public constructor
}
public static MainTabFragment getInstance() {
return sMainTabFragment;
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* #param param1 Parameter 1.
* #param param2 Parameter 2.
* #return A new instance of fragment MainTabFragment.
*/
// TODO: Rename and change types and number of parameters
public static MainTabFragment newInstance(String param1, String param2) {
return new MainTabFragment();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
args = getArguments();
if (args != null && args.containsKey("pos_next"))
position_tab = args.getInt("pos_next");
if (args != null && args.containsKey("pos_end"))
position_child_tab = args.getInt("pos_end");
if (position_child_tab != 3) {
three_childs_tab_position = position_child_tab;
} else {
three_childs_tab_position = 0;
}
args = new Bundle();
args.putInt("pos_end", position_child_tab);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main_tab_fragment, container, false);
myTabLayout = (MyTabLayout) view.findViewById(R.id.mainTabLayout);
pager = (NonSiwpablePager) view.findViewById(R.id.pager);
ViewPagerAdapter mAdapter = getViewPagerAdapter();
pager.setAdapter(mAdapter);
pager.setOffscreenPageLimit(4);
myTabLayout.setupWithViewPager(pager);
for (int i = 0; i < mAdapter.getCount(); i++) {
View customView = mAdapter.getCustomeView(getActivity(), i);
myTabLayout.getTabAt(i).setCustomView(customView);
}
pager.setCurrentItem(position_tab);
pager.setOffscreenPageLimit(3);
// changeTab();
myTabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
pager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
Fragment fragment = getFragmentManager().findFragmentByTag("TOP");
if (fragment != null){
pager.setCurrentItem(position_tab);
}
Log.e("Fragment", fragment + "" +pager.getCurrentItem());
//
return view;
}
public void changeTab(){
pager.getCurrentItem();
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
myTabLayout.getTabAt(position_tab).getCustomView().setSelected(true);
}
public void setCurrentItem(int item) {
pager.setCurrentItem(item);
}
private ViewPagerAdapter getViewPagerAdapter() {
ViewPagerAdapter mAdapter = new ViewPagerAdapter(getChildFragmentManager());
String title_arr[] = {"ADVISORY", "TOP ADVISORS", "EXPERT VIEW"};
for (int i = 0; i < title_arr.length; i++) {
Map<String, Object> map = new Hashtable<>();
map.put(ViewPagerAdapter.KEY_TITLE, title_arr[i]);
if (i == 0) {
map.put(ViewPagerAdapter.KEY_FRAGMENT, AdvisoryPagerFragment.newInstance());
AdvisoryPagerFragment.newInstance().setTargetFragment(this, getTargetRequestCode());
} else if (i == 1) {
map.put(ViewPagerAdapter.KEY_FRAGMENT, TopAdvisoryPagerFragment.newInstance());
TopAdvisoryPagerFragment.newInstance().setTargetFragment(this, getTargetRequestCode());
} else if (i == 2) {
map.put(ViewPagerAdapter.KEY_FRAGMENT, ExperViewPagerFragment.newInstance());
ExperViewPagerFragment.newInstance().setTargetFragment(this, getTargetRequestCode());
}
mAdapter.addFragmentAndTitle(map);
}
return mAdapter;
}
public static class ViewPagerAdapter extends FragmentStatePagerAdapter {
private static final String KEY_TITLE = "fragment_title";
private static final String KEY_FRAGMENT = "fragment";
boolean abc = false;
private int[] drawables = new int[]{R.drawable.advisory_selector, R.drawable.top_advisors_selector, R.drawable.expertview_selector};
private List<Map<String, Object>> maps = new ArrayList<>();
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
public View getCustomeView(Context context, int pos) {
View mView = LayoutInflater.from(context).inflate(R.layout.custom_tab_view, null);
TextView mTextView = (TextView) mView.findViewById(R.id.textView);
mTextView.setTypeface(Typeface.createFromAsset(context.getAssets(), "fonts/ufonts.com_cambria.ttf"));
ImageView mImageView = (ImageView) mView.findViewById(R.id.imageView2);
mImageView.setTag(pos);
/*if(count >0)
{
Toast.makeText(context,"Count Is "+count,Toast.LENGTH_SHORT).show();
mImageView = (ImageView) mImageView.getTag(0);
mImageView.setSelected(false);
}
*/
mImageView.setImageResource(drawables[pos]);
mTextView.setText(getPageTitle(pos));
return mView;
}
public void addFragmentAndTitle(Map<String, Object> map) {
maps.add(map);
}
#Override
public CharSequence getPageTitle(int position) {
return (CharSequence) maps.get(position).get(KEY_TITLE);
}
#Override
public Fragment getItem(int position) {
Log.e("Fragmentss" ,(Fragment) maps.get(position).get(KEY_FRAGMENT) +"");
return (Fragment) maps.get(position).get(KEY_FRAGMENT);
}
#Override
public int getCount() {
return maps.size();
}
}
}
Here I can get that this fragment is visible by using findFragmentByTag. I wanna know how I can use same thing for the child of this Fragment which are added using FragmentPagerAdapter.
Fragment fragment = getFragmentManager().findFragmentByTag("TOP");
if (fragment != null){
Log.e("Fragment", fragment + "" +pager.getCurrentItem()); }
So now I wanna do same thing and get name of current selected Fragment out of 3 which are mentioned above in FragmentPagerAdapter as AdvisoryPagerFragment,TopAdvisoryPagerFragment and ExperViewPagerFragment.

Try this
Fragment fragment = getFragmentManager().findFragmentByTag("TOP");
if(fragment instanceOf Fragment1){
// Do something
}else if(fragment instanceOf Fragment2){
// Do something
}else{
// Do something
}