Develop Reference

conflict between fragments inside a viewpager

whenever i swipe to move to the next fragment the code inside another fragment gets executed tho the layout is loaded properly and the code also but it also executes the code of another fragment
ex: 3 fragments A,b,c
when i swipe from fragment A to fragment b : fragment b layout and code are executed but also fragment c code
when i swipe from b to c , only the code and layout of fragment c ,so its executed properly
so the problem is if it isnt the last fragment it calls the code of next one
here is my main_activty code
public class Main2Activity extends AppCompatActivity {
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
home h1 = new home();
return h1;
case 1:
status st = new status();
return st;
case 2:
info info = new info();
return info;
case 3:
setting set = new setting();
return set;
}
return null;
}
#Override
public int getCount() {
return 4;
}
}
}

Your SectionsPagerAdapter is extending FragmentStatePagerAdapter, and its default behaviour is to preload at least one page for optimisation reasons. You can set the number of fragments it preloads using setOffscreenPageLimit but it has to be at least one.
You can use this method in your fragment and put in there something that you want executed only once the fragment becomes visible:
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
}
}

Launching new Fragment Inside ViewPager

I'm on the verge of losing it. Anyone that could help me solve this issue will be showered with coding props for all of eternity.
I have a Tablayout containing 3 Tabs within my Main Activity. Each tab contains their own Fragment(Tasks,Calendar,Contacts). There is a FAB button in the Main Activity that lives on top of all the Fragments and performs a certain action base on what Tab I'm currently in.
My main issue is that, when I'm in Tab1, and the Fab is clicked, I need to replace the Tasks Fragment with a different Fragment called AddContact.
I've been looking up how to solve this for hours and finally settled on an earlier answer from this stack post
The issue is, I'm not quite grasping how they were able to do it.
My understanding is that the swapping of Fragments should be managed by the getItem method within the View Pager Adapter. And that there should be a listener that exists between the ViewPagerAdapter and the buttonClicked action in my Main Activity that tells it to execute.
The problem is that I can't make this link. I've tried a number of things but with no luck. Below I included my MainActivity Class and my ViewPagerAdapter Class. If someone could please explain to me how I could swap out my Tasks Fragment with my AddContacts Fragment in the ViewPager, I would greatly appreciate it
Main Activity:
public class MainActivity extends AppCompatActivity {
private CollapsingToolbarLayout collapsingToolbarLayout;
private ViewPager viewPager;
private ArrayList<Fragment> fragments = new ArrayList<>();
private ArrayList<String> titles = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
collapsingToolbarLayout = (CollapsingToolbarLayout)findViewById(R.id.collapsing_toolbar);
setSupportActionBar(toolbar);
fragments.addAll(Arrays.asList(new Tasks(),new Calendar(),new Contacts()));
titles.addAll(Arrays.asList(getResources().getString(R.string.fragment_task_title),
getResources().getString(R.string.fragment_cal_title),getResources().getString(R.string.fragment_contacts_title)));
TabLayout tabLayout = (TabLayout)findViewById(R.id.tabs);
final FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);
viewPager = (ViewPager)findViewById(R.id.container);
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager(),fragments,titles);
viewPager.setAdapter(viewPagerAdapter);
viewPager.setCurrentItem(1);
tabLayout.setupWithViewPager(viewPager);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
fabAction();
}
});
}
public void fabAction(){
int current = viewPager.getCurrentItem();
switch (current){
case 0:{
//Need to indicate Fragment Swap here somehow. Through Listener?
break;
}
}
}}
ViewPagerAdapter Class:
public class ViewPagerAdapter extends FragmentPagerAdapter {
ArrayList<Fragment> fragments;
ArrayList<String> titles;
private Fragment mFragmentAtPos0;
public ViewPagerAdapter(FragmentManager fm, ArrayList<Fragment> fragments, ArrayList<String>titles) {
super(fm);
this.fragments = fragments;
this.titles = titles;
}
#Override
public Fragment getItem(int position) {
if (position == 0)
{
if (mFragmentAtPos0 == null)
{
//HANDLES THE CHANGING OF FRAGMENTS IN HERE USING THE LISTENER BELOW? BUT I'M NOT GRASPING THE LOGIC
//ON HOW TO IMPLEMENT THIS.
}
}
return fragments.get(position);
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public CharSequence getPageTitle(int position) {
return titles.get(position);
}
//GOT FROM LESSON - ALLOWS VIEWPAGER TO CHANGE IT'S VIEW AND ATTACH NEW FRAGMENT WHEN LAUNCHED
#Override
public int getItemPosition(Object object)
{
if (object instanceof Tasks && mFragmentAtPos0 instanceof AddContact)
return POSITION_NONE;
return POSITION_UNCHANGED;
}
//GOT FROM LESSON. A LISTENER BUT I'M NOT SURE WHERE AND HOW TO IMPLEMENT IT. WHERE IN THE MAIN ACTIVITY SHOULD THIS
//GO? HOW DOES IT COMMUNICATE BACK TO THE ADAPTER?
public interface FirstPageFragmentListener
{
void onSwitchToNextFragment();
}
The post or lesson that Im referring is also from 5 years ago so I don't know if there's a simpler way to implement this, in which case I would love to hear it. Thanks so much.

Send data from Activity to fragment with ViewPager

I have got aplication with three screens(3 fragments and viewPager), and now I want to send for example String from Activity to FragmentA but I don't know how.
This is my Activity class with pager Adapter
public class MainActivity extends FragmentActivity {
ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager= (ViewPager) findViewById(R.id.pager);
viewPager.setAdapter(new MyAdapter(getSupportFragmentManager()));
}
}
class MyAdapter extends FragmentPagerAdapter{
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int arg0) {
Fragment fragment=null;
if(arg0==0){
fragment=new FragmentA();
}
if(arg0==1){
fragment=new FragmentB();
}
if(arg0==2){
fragment=new FragmentC();
}
return fragment;
}
#Override
public int getCount() {
return 3;
}

You can use the EventBus library or write something similar yourself, but the best option is to learn the correct and accepted methods of communication between components.
If you want to pass the data (String in your case) before the ViewPager initialized you can pass it via argumnents, here you can find a good example.

Reload or refresh list fragment when swiped or when tab is selected?

i am unable to reload/refresh Listfragment (CfFragment(),PfFragment(),IfFragment() in my below code) when tab is selected or swiped, can any one tell me where i am going wrong.My code is working well when it is created for the first time but it doesn't reload/refresh when swiped or selected.If i change anything in the 1st listfragment it should affect in the 2nd list fragment and so on...
Please can any one help me out.it would be much appreciated.
Thank you.
public class busy extends FragmentActivity implements
ActionBar.TabListener {
SessionManager session;
AppSectionsPagerAdapter mAppSectionsPagerAdapter;
static ServiceURL URL;
static AlertDialogManager alert = new AlertDialogManager();
ViewPager mViewPager;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.busy);
session = new SessionManager(getApplicationContext());
mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());
final ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mAppSectionsPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
for (int i = 0; i < mAppSectionsPagerAdapter.getCount(); i++) {
actionBar.addTab(actionBar.newTab().setText(mAppSectionsPagerAdapter.getPageTitle(i)).setTabListener(this));
}
}
#Override
public void onTabUnselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
#Override
public void onTabSelected(ActionBar.Tab tab,FragmentTransaction fragmentTransaction) {
mViewPager.setCurrentItem(tab.getPosition());
//mViewPager.setAdapter(mAppSectionsPagerAdapter);
}
#Override
public void onTabReselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
#TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class AppSectionsPagerAdapter extends FragmentPagerAdapter {
public AppSectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int i) {
switch (i) {
case 0:
return new CfFragment();
case 1:
return new PfFragment();
case 2:
return new IfFragment();
}
return null;
}
#Override
public int getCount() {
return 3;
}
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Confy";
case 1:
return "Peny";
case 2:
return "Incy";
default:
break;
}
return null;
}
}
}

Derive your AppSectionsPagerAdapter class as
public static class AppSectionsPagerAdapter extends FragmentStatePagerAdapter
instead of
public static class AppSectionsPagerAdapter extends FragmentPagerAdapter
Basically, FragmentPagerAdapter keeps the created Fragments in memory, while FragmentStatePagerAdapter destroys and creates them anew as they are shifted in and out of view.
Two more things:
1. Make sure you are not calling setRetainInstance(true) in any of your Fragments, else they won't be recreated.
2. Add
viewPager.setOffscreenPageLimit(0);
to your code.
EDIT:
Instead of
Activity -> ViewPager -> Fragments
create the structure as
Activity -> Fragment -> ViewPager -> Nested Fragments
This will ensure that each Fragment is refreshed on tab change. See this post for the implementation.

Need some explanations about Android fragments and ActionBar tabs

I am trying to understand Android fragments and navigation, but there is something I just don't know how to do. I have created an app, with a MainActivity containing a viewPager :
public class MainActivity extends FragmentActivity implements TabListener
{
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
private String[] tabNames = {"Tab 1", "Tab 2", "Tab 3"};
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
for(int i = 0 ; i < tabNames.length ; i++)
actionBar.addTab(actionBar.newTab().setText(tabNames[i]).setTabListener(this));
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft)
{
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {}
}
Here is TabsPagerAdapter :
public class TabsPagerAdapter extends FragmentPagerAdapter
{
public TabsPagerAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public Fragment getItem(int index)
{
if(index == 0) return new FirstFragment();
else if(index == 1) return new SecondFragment();
else return new ThirdFragment();
}
#Override
public int getCount()
{
return 3;
}
}
And my FirstFragment is a list so it extends ListFragment. Here is what it looks like :
Now I want to go to another view if I click an item. Before I used to do it like this in apps without action bar and tabs :
Intent i = new Intent(this.getActivity().getApplicationContext(), MyNewActivity.class);
startActivity(i);
But now when I do this it doesn't display the action bar on top of the screen anymore, and I also want to keep the navigation state on this tab, if I go to another tab and then come back. What should I do?
Thanks for your help.

It is better to let each individual fragment manage its own menu items (actionbar) so you have to call setHasMenuOptions(true) in each fragment that you want to have menu options in. Get a reference to the actionbar in onActivityCreated() and configure your actionbar how you want it there. You will also have to override the oncreateoptionsmenu and onOptionsItemSelected in the fragment to handle menu item clicks.
Also using the view pager and tabs you want to make each tab a fragment. I don't know about making each tab an activity, and I don't even think that is possible, and if you are doing that then that is your problem. I don't see that from your code, and that is good.
Each tab needs to be a Fragment, so convert all of your activities into fragments and then use the supportFragmentManager to dynamically add and replace fragments to your framelayout resource, or override getItem and return the correct fragment as needed.