Develop Reference

TabLayout with ViewPager not working as expected

There is 3 TabLayout with ViewPager in my application.
If I swipe for change Tabs then it behaves strangely.
Below is the scenario.
Let's say 3 Tabs A, B, C.
Default Tab A will open when I start App.
Go to B From A - Works OK.
Go to A From B - Works Ok.
Go To B From A - Works Ok.
Go To C From B - Works Ok.
Now Problem Starts here.
Go To B From C - It will Load A and B Both but display Only B.
Why A and B loads if I come from C ??
Below is my code.
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
ViewPagerAdapter adapter;
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
private void setupViewPager(ViewPager viewPager) {
adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new FragmentOpen(), "OPEN");
adapter.addFragment(new FragmentClose(), "CLOSE");
adapter.addFragment(new FragmentTest(), "TEST");
viewPager.setAdapter(adapter);
}
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 addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
I want to load Tabs every time.
For that, I use below code.
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
if(adapter != null){
adapter.getItem(position).onResume();
}
Toast.makeText(getApplicationContext(), "Page Selected", Toast.LENGTH_LONG).show();
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
But it will always load both tabs when I came from C.
What I want is: only Tab B must load when came from C, not Both.

Its not possible when using ViewPager. ViewPager loads at least one right/left adjacent fragment of current fragment as per your swipe direction.
If you read the ViewPager documentation, there is a method ViewPager.setOffscreenPageLimit(LIMIT) which supports off screen page limit and its default value is 1.
SetOffscreenPageLimit:
Set the number of pages that should be retained to either side of the
current page in the view hierarchy in an idle state. Pages beyond this
limit will be recreated from the adapter when needed.
This is offered as an optimization. If you know in advance the number
of pages you will need to support or have lazy-loading mechanisms in
place on your pages, tweaking this setting can have benefits in
perceived smoothness of paging animations and interaction. If you have
a small number of pages (3-4) that you can keep active all at once,
less time will be spent in layout for newly created view subtrees as
the user pages back and forth.
You should keep this limit low, especially if your pages have complex
layouts. This setting defaults to 1.
See documentation.
Here are some related answers:
1. ViewPager.setOffscreenPageLimit(0) doesn't work as expected
2. How can make my ViewPager load only one page at a time ie setOffscreenPageLimit(0);
3. How does setOffscreenPageLimit() improve ViewPager performance by retaining more offscreen Fragments?

its Default behavior of ViewPager if you are in A then it loads B
also and when your reach B it will Load C and A also is Loaded now
when to reach at C its destroy the View of A and now when you come
again to B it will Load A again, in a simple way ViewPager Maintain
the One Next and One previous state of View by Default.
to Overcome this you should use ViewPager.setOffscreenPageLimit(number) here number is the count of page to load Simulationally for Next and Previous View.

I had only 3 tabs and settingViewPager.setOffscreenPageLimit(2) worked for me.
Try ViewPager.setOffscreenPageLimit(totTabs - 1)

Tab Layout Select method does not call onTabSelected in android

My application is using Tab Layout . I am creating four tabs in MainActivity(This is the activity which gets launched when i open the Application).
Each tab is associated with a fragment using viewpager . Please refer the below code:
TabLayout tabLayout;
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
pagerAdapter = new MainFragmentPagerAdapter(this, getSupportFragmentManager());
viewPager.setAdapter(pagerAdapter);
// Give the TabLayout the ViewPager
tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(viewPager) {
#Override
public void onTabSelected(TabLayout.Tab tab) {
super.onTabSelected(tab);
}});
This is what i am doing in the onCreate method of the MainActivity.
By default the application shows the first tab as the selected tab . But i want to show the 2ndTab as the selected tab every time application is launched fresh.
So for this i am using following code in the onResume method of MainActivity:
tabLayout.getTabAt(1).select(); //position 1 - means second tab , 0 means tab 1
This api selects the 2nd tab properly.
But Problem 1:-
it does not call the onTabSelected method which i have overridden.
Problem 2: Right After calling tab.select, when i try to get the fragment associated with the 2nd tab, it returns null.
#Override
public void onResume() {
tabLayout.getTabAt(1).select();
Fragment page = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.viewpager + ":" + 1); // position 1 is for 2nd tab.
}
here page is coming as NULL. But if i try to get the page after 2 seconds (using Android Handler postDelayed ). It gives me the proper page value .This is how i get it using handler:
#Override
public void onResume() {
tabLayout.getTabAt(1).select();
handler.postDelayed(getFragment, 2000);
}
private Runnable getFragment = new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
Fragment page = null;
page = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.viewpager + ":" + 1); // position 1 is for 2nd tab
}
};
Now the page value will come proper from the run method.
So how do i resolve problem 1 and is the using handler solution good for second problem.

Hey please check the code below:
TabLayout tabLayout;
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
pagerAdapter = new MainFragmentPagerAdapter(this,getSupportFragmentManager());
viewPager.setAdapter(pagerAdapter);
// Give the TabLayout the ViewPager
tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
viewPager.setCurrentItem(1);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new
TabLayout.ViewPagerOnTabSelectedListener(viewPager) {
#Override
public void onTabSelected(TabLayout.Tab tab) {
super.onTabSelected(tab);
}});

SlidingTabLayout and ViewPager: how to load the current fragment and not the adjacent one at the same time?

I am trying to implement a sliding tab layout that and each fragment should only load when the tab is selected instead i get the adjacent fragment loading, I have tried setOffScreenPageLimit(1) as my code shows but still the adjacent fragment gets loaded any assistance please ???
private SlidingTabLayout tabLayout;
private ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
viewPager.setOffscreenPageLimit(1);
tabLayout = (SlidingTabLayout) findViewById(R.id.tabs);
if (tabLayout != null) {
tabLayout.setViewPager(viewPager);
tabLayout.setDistributeEvenly(true);
tabLayout.setSelectedIndicatorColors(R.color.md_amber_600);
}

I can see you have used setOffScreenPageLimit as 1. It means you are loading only 1 extra screen at a time using viewPager, when actually you want to load nothing. It is not possible to set 0 value for setOffScreenPageLimit this method, actually you can set it but it will not work.
So, it is not possible to achieve this using view pager. If you still want to perform such a functionality, you can use FrameLayout and switch between the fragments based on tab selection.
Below is the tab selection code sample:
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
switchToTab(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});

Android: Updating tab content

I am new to Android development. I have a ViewPager which holds TabLayout (that has fixed number of tabs). The ViewPager has SectionPagerAdapter (that has a fragment corresponding to tabs).
Now, I want to update tab content when user selects the tab and as it becomes visible (or when user wants to refresh the content).
But I am not sure which is correct way I can do this.
So far till now I found two solutions:
1) Add listener to TabLayout:
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
{
#Override
public void onTabSelected(TabLayout.Tab tab)
{
mViewPager.setCurrentItem(tab.getPosition());
// Update tab containts here
}
#Override
public void onTabUnselected(TabLayout.Tab tab)
{
}
#Override
public void onTabReselected(TabLayout.Tab tab)
{
}
});
2) Use ViewPager.OnPageChangeListener to get callbacks for when a page fragment (inside Tab) becomes visible:
viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener()
{
#Override
public void onPageSelected(int position)
{
// Update tab containts here
}
});
Can someone expert in this please advice me?

The way a viewpager adapter works (with tabs) is that once you add your fragments to the viewpager, then you basically need to add content to your fragments and let the adapter manage which fragment is visible when a given tab is selected.
So, by simply using : OnTabSelectedListenerinterface on your tabLayout, all you need to do is `setCurrentItem(tab.getPosition()); on your viewPager reference (from your layout).
You can have a method like this to add fragments to your viewPagerAdapter:
private void setupViewPager(ViewPager viewPager){
//then create an instance of your ViewPagerAdapter class here
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
//then add fragments for each TAB here
//by calling a method inside your Adapter like this
adapter.addFrag(new FragmentOne(), "TITLE HERE");
adapter.addFrag(new FragmentTwo(), "TITLE TWO");
//Now set your adapter here
viewPager.setAdapter(adapter);
}
Now in your fragments, you can show different content accordingly.
I hope this helps!

Best way to set a big Amount of text to Textview

I faced a new problem.
In my app, there is a part we called it X.
The X part have 5 tab ( using Viewpager and ...)
When user click on a button to start X activity, because, I must set text for all of the tabs (and there is 5 of them),there is a delay, based on the phone it's different, on low level phone its about, 4-7 second!!!
so, what can i do to solve the problem?
my way:
1- change my UI design and split the 5 tab into, 5 single activity.
2- use an progress bar( or something like progress bar) and don't change my design.( the problem is i don't know how to do this, i mean i don't know when all of the text are set)
what is the other solutions?
So, if i want to use AsynckTask, the code would be like this right?
Main:
public class Law_main extends AppCompatActivity {
FrameLayout fl_TEMP;
TextView btn_ASD;
ViewPager viewPager;
PagerAdapter adapter;
TabLayout tabLayout;
ProgressBar progressBar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.law_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
progressBar = (ProgressBar) findViewById(R.id.progressBar);
tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("TAB 1"));
tabLayout.addTab(tabLayout.newTab().setText("TAB 2"));
tabLayout.addTab(tabLayout.newTab().setText("TAB 3"));
tabLayout.addTab(tabLayout.newTab().setText("TAB 4"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
fl_TEMP = (FrameLayout) findViewById(R.id.TEMP);
btn_ASD = (TextView) findViewById(R.id.ASD);
new TxtTimer().execute();
final View appbar = findViewById(R.id.appbar);
viewPager = (ViewPager) findViewById(R.id.pager);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
private class TxtTimer extends AsyncTask<String, Integer, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... strings) {
return null;
}
#Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
adapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.setCurrentItem(1, true);
progressBar.setVisibility(View.GONE);
}
}
}
this code act like this:
When user Click on to open X activity, user stay in the activity and then after a while, when all text got set, the x activity is open, so it's not helping at all.
Were am i wrong?

Depending on how you are retrieving your text, consider using an AsyncTask. You can also put a progress circle on the fragment whilst it is loading so that the app doesn't appear to have frozen.

Building on what RobVoisey stated, and not knowing exactly your use case, I would load the first tab's text first to give the user something to look at and simultaneously load the text for the other tabs using AsyncTask whileshowing a loading graphic where appropriate and/or necessary.

use fragments inside your tabs and load the content on demend using fragment lifecycle, youll have a starting point of 1/5 text being loaded on each fragment.