I used sherlock to have action bar in android 2.3, everythings is ok but the problem is:
I have 4 tabs, after doing some works on fisrt tab if I go to the second and third tab when I came back to first tab the contetnt is ok but when I go to the last tab and then came back to the first, the conent of first fragment was restarted and everything was gone, below is my codes, why is it like that?
MainActivity:
public class MainActivity extends SherlockFragmentActivity implements
TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private com.actionbarsherlock.app.ActionBar actionBar;
private String[] tabs = { "weblog", "news", "image", "web" };
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getSupportActionBar();
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setDisplayShowHomeEnabled(false);
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
actionBar.setHomeButtonEnabled(false);
viewPager.setAdapter(mAdapter);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.addTab(actionBar.newTab().setText(tabs[0])
.setTabListener(this), false);
actionBar.addTab(actionBar.newTab().setText(tabs[1])
.setTabListener(this), false);
actionBar.addTab(actionBar.newTab().setText(tabs[2])
.setTabListener(this), false);
actionBar.addTab(actionBar.newTab().setText(tabs[3])
.setTabListener(this), true);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public void onTabSelected(com.actionbarsherlock.app.ActionBar.Tab tab,
android.support.v4.app.FragmentTransaction ft) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(com.actionbarsherlock.app.ActionBar.Tab tab,
android.support.v4.app.FragmentTransaction ft) {
}
#Override
public void onTabReselected(com.actionbarsherlock.app.ActionBar.Tab tab,
android.support.v4.app.FragmentTransaction ft) {
}
}
TabsPagerAdapter:
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new Blog();
case 1:
return new News();
case 2:
return new Image();
case 3:
return new Search();
}
return null;
}
#Override
public int getCount() {
return 4;
}
}
The ViewPager typically only keeps a few fragments in an "idle" state and recreates the other fragments as a performance optimization. See this answer.
To override this behavior, you can call setOffscreenPageLimit
// keep 3 tabs in memory on either side of the current tab
viewPager.setOffscreenPageLimit(3);
Related
I have a ViewPager and an ActionBar with tabs that change fragments when clicked. I want to send the text of the tab (ie. tab.getText()) to the fragment that is created.
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
viewPager.setCurrentItem(tab.getPosition());
String text = tab.getText();
}
I'm not sure how to pass that on to the fragment that is created.
This is my MainActivity:
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
String[] tabs = {this.getCurrentDate(-5).toString(),this.getCurrentDate(-4).toString(),this.getCurrentDate(-3).toString(), this.getCurrentDate(-2).toString(),this.getCurrentDate(-1).toString(),
this.getCurrentDate(0).toString(),
this.getCurrentDate(1).toString(), this.getCurrentDate(2).toString(), this.getCurrentDate(3).toString(), this.getCurrentDate(4).toString(), this.getCurrentDate(5).toString(),};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
actionBar.setSelectedNavigationItem(5);
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
public String getTab(Tab tab) {
return tab.getText().toString();
}
#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) {
}
public String getCurrentDate(int offset) {
String calAsString;
DateFormat formatter = new SimpleDateFormat("MM/dd");
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, offset);
calAsString = formatter.format(cal.getTime());
return calAsString;
}
}
This is my ViewPager adapter:
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new TopRatedFragment();
case 1:
// Games fragment activity
return new TopRatedFragment();
case 2:
// Movies fragment activity
return new TopRatedFragment();
case 3:
return new TopRatedFragment();
case 4:
return new TopRatedFragment();
case 5:
return new TopRatedFragment();
case 6:
return new TopRatedFragment();
case 7:
return new TopRatedFragment();
case 8:
return new TopRatedFragment();
case 9:
return new TopRatedFragment();
case 10:
return new TopRatedFragment();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 11;
}
}
This is one possible solution, first create all 11 fragments, save them in an arrayList then pass them to your adapter:
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
private ArrayList<TopRatedFragment> myFragmentList = ArrayList<TopRatedFragment>();
// Tab titles
String[] tabs = {this.getCurrentDate(-5).toString(),this.getCurrentDate(-4).toString(),this.getCurrentDate(-3).toString(), this.getCurrentDate(-2).toString(),this.getCurrentDate(-1).toString(),
this.getCurrentDate(0).toString(),
this.getCurrentDate(1).toString(), this.getCurrentDate(2).toString(), this.getCurrentDate(3).toString(), this.getCurrentDate(4).toString(), this.getCurrentDate(5).toString(),};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
for (String tab_name : tabs) {
TopRatedFragment fm = new TopRatedFragment();
fm.method(tab_name);
myFragmentList.add(fm);
}
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager(), myFragmentList);
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
actionBar.setSelectedNavigationItem(5);
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
and in your adapter get the list and create everything according to that:
public class TabsPagerAdapter extends FragmentPagerAdapter {
ArrayList<TopRatedFragment> myList;
public TabsPagerAdapter(FragmentManager fm, ArrayList<TopRatedFragment> myList) {
super(fm);
this.myList = myList;
}
#Override
public Fragment getItem(int index) {
myList.get(index);
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return myList.size();
}
}
in this solution you can change the number of tabs just by changing the String[] tabs.
so now you can do a lot of thing:
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
myFragmentList.get(tab.getPosition()).Call any method;
}
Good Luck!
Hi i am trying this for 2 week and still not able to replace a fragment with another in viewpager. I have three fragments as tabs in viewpager ,when i click a button in the first fragment , i want to replace the firstfragment with fourthfragment. Iam doing a below but it is not working
productDetailFragment = new PlaceSearchFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.addToBackStack("fh");
transaction.replace(R.id.maincontainer,productDetailFragment,"yourfragment").commit();
Below is my MainActivity with viewpager
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "New", "Recent", "All" };
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// on tab selected
// show respected fragment view
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
}}
Below is my Fragmentpageadapter
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
// Top Rated fragment activity
return new GetRideFragment();
case 1:
// Games fragment activity
return new PostRideFragment();
case 2:
// Movies fragment activity
return new SearchRidesFragment();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
}
searched alot and tried different ways but i am not able to make it work.Any working example or a solution to this will be very helpful.Any help is very much appreciated
I would like to create a new fragment every time when I click its tab.
I tried to get the tab and to create a fragment. But it doesn't seem to work.
Here is my code.
Main Activity
public class MainActivity extends FragmentActivity {
private static ViewPager viewPager;
private static TabsPagerAdapter mAdapter;
private static ActionBar actionBar;
// Tab titles
private String[] tabs = { "TopRated", "Hots", "NEW"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initialization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
//actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(tabListener));
}
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
static ActionBar.TabListener tabListener = new ActionBar.TabListener() {
#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) {
}
};
TabsPagerAdapter
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new TopRatedFragment();
case 1:
return new HotStoryFragment();
case 2:
return new AllClassFragment();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
One of the fragments
public class HotStoryFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.d("Refresh_F","(2) HotStory");
View rootView = inflater.inflate(R.layout.fragment_hotstory, container, false);
TextView tvStudy = (TextView)rootView.findViewById(R.id.text);
return rootView;
}
I want to replace a Fragment by a new Fragment when an onClick method is called. I wanted to do it this way:
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.remove(this);
transaction.addToBackStack(null);
transaction.add(new ChooseCocktailFragment(), null);
transaction.commit();
The only thing that happens is the current Fragment is removed and the new one doesn't show. What am I doing wrong here?
Also, I use a ViewPager and this is the first time for me working with fragments. Usually I would have a Container with its ID but here the ViewPager contains the fragments, therefore I don't know how to use the transaction.replace(...) method.
You should use a FragmentPagerAdapter which is adequate to put Fragments inside ViewPagers.
A complete tutorial from android developer here
EDIT:
First of all, you need to override the getItemPosition of the adapter, and return the POSITION_NONE constant in order to be able to replace pager's fragments.
#Override
public int getItemPosition(Object object)
{
return POSITION_NONE;
}
Then create a listner for handling fragment switching:
public interface MyListener
{
public void onFragmentChange();
}
Your adapter should implements the listner and add some code inside onFragmentChange() method:
public class TabsPagerAdapter extends FragmentPagerAdapter {
private FragmentManager fm;
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
this.fm = fm;
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
fragment1 = TopRatedFragment.newInstance(this);
return fragment1;
case 1:
// ...
return fragment2;
case 2:
// ...
return fragment3;
case 3:
// ...
return fragment4;
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 4;
}
public void onFragmentChange(){
fm.beginTransaction().remove(fragment1).commit();
fragment1 = NewFragment.newInstance();
notifyDataSetChanged(); // notify the viewpager adapter that content has changed
}
}
Pass an instance of the listner in the fragment you want to remove/replace later :
public class TopRatedFragment extends Fragment {
public static TopRatedFragment newInstance(MyListner listner) {
this.myListner = listner;
return new TopRatedFragment ();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);
return rootView;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// some logical here ... and when you want to change fragment do this
myListner.onFragmentChange();
}
}
Here is some more explanation of this.
You should also read about FragmentStatePagerAdapter : here
Hope it helps !
You forget hide your fragment after another fragment is added up on your fragment.
Just add more a statement transaction.hide(Your_Fragment) before transaction.commit()
#mansoulx
Here is my code which my answer refers to. Since i implemented it using a tutorial it is very similiar, just Tab names and the content of the tabs changed. I also have 4 tabs, not three - but the problem would be the same:
TabsPagerAdapter.java
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new Fragment1();
case 1:
return new Fragment2();
case 2:
return new Fragment3();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
}
MainActivity.java
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Tab1", "Tab2", "Tab3" };
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// on tab selected
// show respected fragment view
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
let's say all Fragments would look like this:
Fragment1.java
public class TopRatedFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);
return rootView;
}
}
The thing which should be done now is:
Replace Fragment1 on Tab1 with FragmentNew which should appear in Tab1 too! The OnClick-Event takes place in the fragment1.java for example...
I know many applications using fragments in ViewPager. I need it in my application too. I have no found any guide how I can to do it exclude this. And here is my code:
public class MainActivity extends FragmentActivity {
Vector<Fragment> fragments;
ViewPager viewPager;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
viewPager = (ViewPager) findViewById(R.id.pager);
fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, Fragment1.class.getName()));
fragments.add(Fragment.instantiate(this, Fragment2.class.getName()));
viewPager.setOffscreenPageLimit(fragments.size());
PagerAdapter pagerAdapter = new PagerAdapter(super.getSupportFragmentManager(), fragments);
viewPager.setAdapter(pagerAdapter);
viewPager.setCurrentItem(0);
}
class PagerAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
#Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}
#Override
public int getCount() {
return this.fragments.size();
}
}
}
But this code doesn't working well. Sometimes I get error in my Fragment1 about getActivity() return null. I read many posts from this site and other about this error and now I know that is bad way - use Vector for storing fragments. But I still don't know, how to do ViewPager with fragments properly. Please, help.
Even I had trouble understanding the concept at first and I won't say that I fully understood it. But,
Here's how I am using fragment in my sample application:
Step 1: Creating my Adapter:
public class AllPagesAdapter extends FragmentStatePagerAdapter {
public AllPagesAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new Fragment1();
case 1:
return new Fragment2();
case 2:
return new Fragment3();
case 3:
return new Fragment4();
case 4:
return new Fragment5();
}
return null;
}
#Override
public int getCount() {
return 5;
}
}
Step 2: In the main activity, I am extending fragment activity and implementing an ActionBar.TabListener. Here's how I am doing it:
public class SomeActivity extends FragmentActivity implements ActionBar.TabListener {
public ViewPager viewPager;
private AllPagesAdapter mAdapter;
private ActionBar actionBar;
private String [] tabs = {"Fragment1","Fragment2","Fragment3","Fragment4","Fragment5"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initializing all stuff
viewPager = (ViewPager)findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new AllPagesAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(true);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
//Add the tabs here
for(String tab_name:tabs){
actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
}
viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){
#Override
public void onPageSelected(int position){
//on Page change, that particular page should be selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0,float arg1,int arg2){
}
#Override
public void onPageScrollStateChanged(int position){
}
});
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction fragmentTransaction) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction fragmentTransaction) {
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction fragmentTransaction) {
viewPager.setCurrentItem(tab.getPosition());
}
}
Step 3: I have just one fragment for this example:
Here's the code:
public class Fragment1 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
//Can be layout you want it to be.
View databaseview = inflater.inflate(R.layout.database, container, false);
return databaseview;
}
}
Step 4: Last part is the layout: This will be starting point.
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"></android.support.v4.view.ViewPager>
Lastly, one important thing is that, number of fragments should be equal to the string array defined in the main activity. If not, the app crashes.
Hope I explained it well..:)
I know this is a very old post but this answer can be used for future viewers.