Develop Reference

How to restrict to view pager to not execute any code from other fragment

I have a view pager which contains 2 fragment.
Now when user loads the activity, both of view gets loaded, they both contain analytics tag, and apps sends view tag from both of the fragments.
I want to restrict this. I want it to not execute any code from fragment2 unless user taps on it from view pager tab.

In the case of ViewPager, it is not possible I think...the minimum offScreenPageLimit is default set to 1. So it will load one page each side by default. So better you make it a custom view and load fragment according to the user taps.
Or check this workaround maybe this can be helpful in your case. I have never tried it but you can give it a shot

you can do the stuff after fragment gets visible
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
}
else {
}
}

The best implementation of a viewpager is to recycle the viewpager items. And you can achieve it by using offScreenPageLimit.
However, answering your question, i have faced similar situation myself and there is no perfect solution yet to achieve such a scenario. But there are certain hacks that you can do.
One solution is to use
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
}
else {
}
}
This will execute only when fragment is visible to user.
But this function too has some pitfalls. In some edge cases, this doesn't execute as well which will lead to an empty fragment.
The hack that I do is to use "OnTabSelectedListener" if I am integrating viewpager with tablayout and if there is only Viewpager you can override "OnPageSelectedListener".
If you are using OnTabSelectedListener, you will get callbacks in "OnTabSelected()" method when a tab is selected. So when you get the callback, use a public function in the respective fragment to load the data(Api calls, setting adapter etc).
Hope this helps

Fragment lifecycles in ViewPager

There is a ViewPager with Fragments generated dynamically.
Questions:
What is the way to catch the moment when user slides away from the fragment (so I can bring it into "clean", "init" state)?
or
How to catch moment when a Fragment is scrolled in?
Problems:
Have checked Fragment Lifecycle, but none of them is getting triggered when scrolled out/in (using ViewPager)
Lifecycle phases are triggered only if I scroll 2+ Fragments (those 3rd one is getting Paused/Resumed).

To get a callback when a fragment gets visible to the user you can override the setUserVisibleHint method, like this:
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if(isVisibleToUser){
//Put your 'init' logic here
}
}
the variable isVisibleToUser will give the status of the visibility, so you can use the same method to handle when the fragment goes out.

addOnPageChangeListener
void addOnPageChangeListener (ViewPager.OnPageChangeListener listener)
Add a listener that will be invoked whenever the page changes or is incrementally scrolled. See ViewPager.OnPageChangeListener.
Components that add a listener should take care to remove it when finished. Other components that take ownership of a view may call clearOnPageChangeListeners() to remove all attached listeners.
You can implement this listener to track the movement of the fragments in the ViewPager.
There is also a method setOffscreenPageLimit() which Set the number of pages that should be retained to either side of the current page and it's default value is 1 and minimum value can be set to 0.

Stop preloading pages in viewpager example

I am looking for and example source code for stop pre-loading pages in viewpager. Normally android viewpager loads the next and previous page(s) automatically. My target is to use viewpager and I want to show animation on views(which are present in the pages) when it visible to the user. Basically it is to continue with the previous of post.
If you can give me any working example(complete code) it will be so kind. I found so many but did not find any working implementation.
Thanks for your help.
Regards
Biswajit

Like you already know there is no way of stopping viewpagers from loading . The only way out is to use this method setUserVisibleHint add this to your fragment, and do all the animation you want to in this method
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
// animate here
Log.e(TAG, "animate here");
}else{
Log.e(TAG, "fragment is no longer visible");
// fragment is no longer visible
}
}
This will be called only when that particular tab is visible to user.

Android - how to refresh tab contents

I have two tabs with fragments created in my activity, the data of the second tab depends on the first tab data.
Both the tabs are containing list items, when I delete an item from first tab's list, it gets deleted but the second tab still shows the data. I need to go back from activity and load again to see the updated data in second tab.
Is there any way that I can refresh the second tab content whenever I delete/update list item of first tab?
Note: I have tried -
detach()
attach()
and
runQueryOnBackgroundThread()
notifyDataSetChanged()
In onResume nothing seems to be working. Any help would help a lot

You should learn about Interface communication. Read this http://developer.android.com/training/basics/fragments/communicating.html will help you.

you should override setUserVisibleHint method in your fragment and put your refreshing code in it
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser && isResumed()) {
}
}
I got this code in help.Hope it will help more people.Or refer my question here
http://stackoverflow.com/questions/40505019/how-to-refresh-tabs-content-dynamically-while-switching-between-one-tab-to-other/40505242#40505242

Android fragments hide show OnHide/OnShow?

I am asking this cuz I am sort of curious.
1 ) Most google demos finds fragments by its ID if the fragment is already been created in xml.
So if we take that approach, the way we show fragments is by hiding it and showing it since the fragments are already created.
2) There are also examples provided by google where you can create the fragment with a constructor and inflate it. This acts weird by the way like getActivity() returns null if it is called with in that fragment.
So If i take the first approach I have to hide and show the fragments.
So why does not google provide hooks to the fragments like onHide or onShow
so that we can handle things properly instead if doing the clean up ourselves with functions that we implement and call explicitly.

If you want to hook op on onHide/onShow just override
public void onHiddenChanged(boolean hidden) {
}
in your fragment.

By Overrinde setUserVisibleHint you can easily track it.
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if(isVisibleToUser){
//When fragment is visible
}
Log.i("my_fragment","setUserVisibleHint: "+isVisibleToUser);
}

I override the function below to determine whether a fragment is shown or hidden.
#Override
public void setMenuVisibility(final boolean visible)