Fragment (swipe) and Button listener issue

Fragment (swipe) and Button listener issue - java

First of all excuse my stupid knowledge of android, because I'm new in it.
We have some codes here that changes tabs with swipe gesture with 3 Fragments that named: "Top Rated", "Games", "Movies".
This is the source codes
Here is MainActivity activity:
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Top Rated", "Games", "Movies" };
#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));
}
/**
* 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) {
}
});
}
#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) {
}
}
With this adapter
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 TopRatedFragment();
case 1:
// Games fragment activity
return new GamesFragment();
case 2:
// Movies fragment activity
return new MoviesFragment();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
}
This is main xml:
<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>
One of Fragments (others are like this)
public class GamesFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_games, container, false);
return rootView;
}
}
With this XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ff8400" >
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Design Games Screen"
android:textSize="20dp"
android:layout_centerInParent="true"/>
</RelativeLayout>
Now we want to add a button in this page see this XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ff8400" >
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Design Games Screen"
android:textSize="20dp"
android:layout_centerInParent="true"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Button"
android:id="#+id/button"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"/>
</RelativeLayout>
One way to do this is define button and listener in GamesFragment.java
that is impossible, because it can't be define in that class.
final Button button = (Button) findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// do some thing
}
});
Second way is merge GameFragment java codes with main codes. And edit main activity like this:
setContentView(R.layout.activity_main & R.layout.fragment_games);
That I can't write codes correctly.
Third way is we should write our fragments in main activity that use one layout.
Now can u help me to solve this?

final Button button = (Button) rootView.findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// How to start a new activity form here?????
}
});
This worked quite well.

Related

Can't swipe between tabs in TabLayout

I'm able to click the tabs to change, but nothing happens when I swipe. I don't see the coloured bar underneath the selected tab either.
Here's my code. I've largely followed this tutorial, but I've changed tabLayout.setOnTabSelectedListener(this) to tabLayout.addOnTabSelectedListener(this) in StoriesActivity because the former is depreceated.
StoriesActivity:
public class StoriesActivity extends AppCompatActivity implements TabLayout.OnTabSelectedListener {
//This is our tablayout
private TabLayout tabLayout;
//This is our viewPager
private ViewPager viewPager;
private Toolbar toolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stories);
/* +++ START Intent +++ */
Bundle extras = getIntent().getExtras();
final int authorID = extras.getInt("author_id");
final String authorName = extras.getString("author_name");
Log.i("click", Integer.toString(authorID));
/* +++ END Intent +++ */
toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle(authorName);
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
finish();
}
});
//Initializing the tablayout
tabLayout = (TabLayout) findViewById(R.id.tab_layout);
//Adding the tabs using addTab() method
tabLayout.addTab(tabLayout.newTab().setText("Stories"));
tabLayout.addTab(tabLayout.newTab().setText("Collections"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
//Initializing viewPager
viewPager = (ViewPager) findViewById(R.id.pager);
//Creating our pager adapter
StoriesTabsAdapter adapter = new StoriesTabsAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
//Adding adapter to pager
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
//Adding onTabSelectedListener to swipe views
tabLayout.addOnTabSelectedListener(this);
}
#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) {
}
}
activity_stories.xml:
<RelativeLayout
android:id="#+id/main_layout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
app:navigationIcon="?attr/homeAsUpIndicator"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
<android.support.design.widget.TabLayout
android:id="#+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/toolbar"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"/>
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="#id/tab_layout"/>
<ListView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/stories_list_view" />
</RelativeLayout>
StoriesTabsAdapter:
public class StoriesTabsAdapter extends FragmentPagerAdapter {
int mNumOfTabs;
public StoriesTabsAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
StoriesFragment tab1 = new StoriesFragment();
return tab1;
case 1:
CollectionsFragment tab2 = new CollectionsFragment();
return tab2;
default:
return null;
}
}
#Override
public int getCount() {
return mNumOfTabs;
}
}
StoriesFragment:
public class StoriesFragment extends Fragment {
public StoriesFragment() {
// Required empty public constructor
}
private ListView storiesListView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_stories, container, false);
}
}

You are missing to setupWithViewPager your TabLayout.
mTabLayout.setupWithViewPager(mViewPager)
Regarding the problem of your text not to be appearing, try to move the code below straight after you setupWithViewPager
//Adding the tabs using addTab() method
tabLayout.addTab(tabLayout.newTab().setText("Stories"));
tabLayout.addTab(tabLayout.newTab().setText("Collections"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

You should follow below two points.
Use FragmentStatePagerAdapter for good approach.
setupWithViewPager
If you're using a ViewPager together with this layout, you can call
setupWithViewPager(ViewPager) to link the two together. This layout
will be automatically populated from the PagerAdapter's page titles.
Secondly
_tablayoutOBJ.setupWithViewPager(_viewpagerOBJ); // After addOnTabSelectedListener .
For, Demo case you can visit Material Design working with Tabs.

Android Fragment Always NULL When Accessing From ViewPagerAdapter

The Problem:
In my onCreate() on my main activity, I am trying to set the text value of a TextView in my fragment which is displayed by a viewpager. When I try to get my fragment instance, It always returns null.
Solutions I Tried:
Almost every solution related to this problem on SO gives me the same result(NPE).
My Code is below as well as some explanation...
Home.java Activity (My Main Activity):
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Show the home layout
setContentView(R.layout.home);
// Setup the toolbar
Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Now setup our tab bar
TabLayout tabLayout = (TabLayout)findViewById(R.id.homeTabs);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
// Setup the view pager
ViewPager viewPager = (ViewPager)findViewById(R.id.viewPager);
PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(pagerAdapter);
tabLayout.setupWithViewPager(viewPager);
// Start our service controller
Intent startServiceController = new Intent(this, ServiceController.class);
startService(startServiceController);
Fragment viewFragment = pagerAdapter.getRegisteredFragment(viewPager.getCurrentItem());
if(viewFragment == null){
Log.v("Fragment", "NULL");
}
}
After setting up the pageAdapter and viewpager, I try to access the fragment thats being shown. The code for my PagerAdapter is below...
PagerAdapter:
public class PagerAdapter extends SmartFragmentStatePagerAdapter {
public PagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new ParkListFragment();
case 1:
return new MapFragment();
default:
return null;
}
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
CharSequence title;
switch (position){
case 0:
title = "Spaces Near You";
break;
case 1:
title = "Map";
break;
default:
title = "N/A";
break;
}
return title;
}
}
SmartFragmentStatePagerAdapter:
public abstract class SmartFragmentStatePagerAdapter extends FragmentStatePagerAdapter {
// Sparse array to keep track of registered fragments in memory
private SparseArray<Fragment> registeredFragments = new SparseArray<>();
public SmartFragmentStatePagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
// Register the fragment when the item is instantiated
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
// Unregister when the item is inactive
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
// Returns the fragment for the position (if instantiated)
public Fragment getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
}
I really don't understand what the issue is. I have tried many things. What I don't want to use is this:
String tag="android:switcher:" + viewId + ":" + index;
ParkListFragment.java:
public class ParkListFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.park_list_fragment, container, false);
}
}
ParkList Fragment Layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.5">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_centerInParent="true">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/confidenceText"
android:textAlignment="center"
android:textSize="24sp"
android:textColor="#android:color/primary_text_light"
android:padding="10dp"/>
</LinearLayout>
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.5">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_centerInParent="true">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/activityText"
android:textAlignment="center"
android:textSize="24sp"
android:textColor="#android:color/primary_text_light"
android:padding="10dp"/>
</LinearLayout>
</RelativeLayout>
</LinearLayout>
Stack Trace: Pastebin

So after hours of trial and error, the only thing that worked for me was this SO post:
ViewPager Fragments are not initiated in onCreate

accessing fragment's view from activity with function

I am trying to dynamically change a text from a fragment textview inside de activity but I keep getting 'cannot obtain root' error. I tried to instantiate the textview inside onCreateView and inside onActivityCreated as well but it doesnt work. How can I change the text from a fragment textview inside the activity?
Fragment xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Tab 1"
android:textAppearance="?android:attr/textAppearanceLarge"/>
</RelativeLayout>
Fragment Code:
public class TabFragment1 extends Fragment {
private TextView tv;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.tab_fragment_1, container, false);
return view;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
tv = (TextView) getView().findViewById(R.id.textView);
}
public void setText(String text){
tv.setText(text);
}
}
Main xml:
<RelativeLayout
android:id="#+id/main_layout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
<android.support.design.widget.TabLayout
android:id="#+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/toolbar"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"/>
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="#id/tab_layout"/>
</RelativeLayout>
Main code:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout 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.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), tabLayout.getTabCount());
TabFragment1 t1 = new TabFragment1();
TabFragment2 t2 = new TabFragment2();
TabFragment3 t3 = new TabFragment3();
adapter.newFrag(t1);
adapter.newFrag(t2);
adapter.newFrag(t3);
viewPager.setAdapter(adapter);
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) {
}
});
t1.setText("HELLO WORLD");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
PagerAdapter:
public class PagerAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
List<Fragment> aFrag;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
aFrag = new ArrayList<Fragment>();
}
public void newFrag(Fragment f){
aFrag.add(f);
}
#Override
public Fragment getItem(int position) {
return aFrag.get(position);
}
#Override
public int getCount() {
return mNumOfTabs;
}
}

You try to set text on view, but this view wasn't created, this fragment wasn't created. If You want to set text from activity you can pass bundle to fragment arguments with that text, and in fragment chceck bundle and set text. Later if you want to change text in this fragment then you can use your function.
public class TabFragment1 extends Fragment {
private TextView tv;
public static TabFragment1 create(String text){
Bundle b = new Bundle();
b.putString("textdata",text);
TabFragment1 f = new TabFragment1();
f.setArguments(b);
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.tab_fragment_1, container, false);
tv = (TextView) view.findViewById(R.id.textView);
if(getArguments()!=null){
tv.setText(getArguments().getString("textdata"));
}
return view;
}
public void setText(String text){
tv.setText(text);
}
}
In your activity create this fragment using static method:
TabFragment1 t1 =TabFragment1.create("HELLO WORLD");
Hardcore execution of your base code is:
new Handler().postDelayed(new Runnable(){t1.setText("HELLO WORLD");},300);

Fragment move from one Fragment to another by sliding as well as button click

I have a view that consist of three buttons, a fragment and a ViewPager. If you press button1 then fragment one should be shown. If you press button two then fragment two is shown. If you press button three then fragment Three is shown. As well as sliding should happen from from fragment one to fragment tow and fragment two to fragment three. The problem is that If I execute separate fragment and ViewPager it runs. But I want both in single layout. Error show in this line : fragmentTransaction.replace(R.id.fragment_place, fr); and error is :The method replace(int, Fragment) in the type FragmentTransaction is not applicable for the arguments (int, Fragment);
so please anybody tell me how to fix this problem. I used both fragment as well as ViewPager. Can I use both in single layout.
How can I solve this problem so both will happen like sliding as well as fragment move by button click?
MainActivity.java class
public class MainActivity extends FragmentActivity {
private PageAdapter mPageAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpages_layout);
initialingpaging();
}
private void initialingpaging() {
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, Fragment1.class.getName()));
fragments.add(Fragment.instantiate(this, Fragment2.class.getName()));
fragments.add(Fragment.instantiate(this, Fragment3.class.getName()));
mPageAdapter = new PageAdapter(this.getSupportFragmentManager(), fragments);
ViewPager pager = (ViewPager)findViewById(R.id.viewpager);
pager.setAdapter(mPageAdapter);
}
public void selectFrag(View view) {
Fragment fr;
switch (view.getId()) {
case R.id.button1:
fr = new Fragment1();
break;
case R.id.button2:
fr = new Fragment2();
break;
case R.id.button3:
fr = new Fragment3();
break;
default:
break;
}
FragmentManager fm = getFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.fragment_place, fr);
fragmentTransaction.commit();
}
}
// PageAdapter.java class
public final class PageAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public PageAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
// TODO Auto-generated constructor stub
this.fragments = fragments;
}
#Override
public Fragment getItem(int arg0) {
return this.fragments.get(arg0);
}
#Override
public int getCount() {
return this.fragments.size();
}
}
//Fragment1.java, Fragment2.java and Fragment3.java class are like below code:
public class Fragment3 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if(container == null) {
return null;
}
return (LinearLayout) inflater.inflate(R.layout.fragment3_layout,container,false);
}
}
//fragment1_layout.xml, fragment2_layout.xml and fragment3_layout.xml are like similar code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FF0000"
android:orientation="vertical" >
</LinearLayout>
//viewpages_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="#+id/button1"
android:layout_width="110dp"
android:layout_height="wrap_content"
android:onClick="selectFrag"
android:text="Fragment 1" />
<Button
android:id="#+id/button3"
android:layout_width="110dp"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:onClick="selectFrag"
android:text="Fragment 3" />
<Button
android:id="#+id/button2"
android:layout_width="110dp"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:onClick="selectFrag"
android:text="Fragment 2" />
<android.support.v4.view.ViewPager
android:id="#+android:id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginTop="100dp"/>
<fragment
android:id="#+id/fragment_place"
android:name="com.example.viewpageexample1.Fragment1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="70dp" />
</RelativeLayout>

Make sure that you have imported the right Fragment class.
There is Fragment class in android.app and in android.support.v4.app.
I think you are using android.support.v4.app.Fragment and fragmentTransaction.replace(int, Fragment) method uses android.app.Fragment.
So to make it work, change getFragmentManager() to getSupportFragmentManager() and fix imports to use classes from android.support.v4.app.

I think instead of 3 buttons, you should try action bar tabs..here is the code for the same.
add implements clause to your class definition.
public class MainActivity extends FragmentActivity implements ActionBar.TabListener{
Initialize the following inside your class
ActionBar bar;
ViewPager viewpager;
PageAdapter ft;
In onCreate, replace your code with this.
viewpager = new ViewPager(this);
viewpager.setId(R.id.pager);
setContentView(viewpager);
ft = new FragmentPageAdapter(getSupportFragmentManager());
viewpager.setAdapter(ft);
final ActionBar bar = getActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
bar.addTab(bar.newTab().setText("Fragment1").setTabListener(this));
bar.addTab(bar.newTab().setText("Fragment2").setTabListener(this));
bar.addTab(bar.newTab().setText("Fragment3").setTabListener(this));
viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
bar.setSelectedNavigationItem(arg0);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
#Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.start_screen, menu);
return true;
}
#Override
public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
#Override
public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
viewpager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
In viewpager_layout, only have this. Remove everything else.
<android.support.v4.view.ViewPager
android:id="#+android:id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginTop="100dp"/>;
PageAdapter code should be like this.
public class PageAdapter extends FragmentPagerAdapter {
public PageAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int arg0) {
switch (arg0)
{
case 0:
return new Fragment1();
case 1:
return new Fragment2();
case 2:
return new Fragment3();
default:
break;
}
return null;
}
#Override
public int getCount() {
// TODO Auto-generated method stub
return 3;
}
}
Your Fragment xml / change background color between 3 xmls to see results.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/fragment1"
android:orientation="vertical"
android:background="#00FF33">
</LinearLayout>
Your Fragment1/2/3 code
public class Fragment1 extends Fragment {
View myFragmentView;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
myFragmentView = inflater.inflate(R.layout.fragment1, container, false);
return myFragmentView;
}
}
checkout http://semycolon.blogspot.in/2014/11/first-android-app-step-5-homescreen.html. It has a complete explanation with source code.

put tabs in the bottom of screen

I want to put tabs at the bottom part of my screen . For this purpose I have the following code :
package info.androidhive.tabsswipe;
import info.androidhive.tabsswipe.adapter.TabsPagerAdapter;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Top Rated", "Games", "Movies" };
#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.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.setDisplayShowHomeEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
/**
* 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) {
}
});
}
#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) {
}
}
By this code , I have the following layout :
package info.androidhive.tabsswipe;
import info.androidhive.tabsswipe.adapter.TabsPagerAdapter;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Top Rated", "Games", "Movies" };
#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.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.setDisplayShowHomeEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
/**
* 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) {
}
});
}
#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) {
}
}
By this code , This is how the screen looks after compilation :
How can I put tabs at the bottom of the screen ?

Actually it's against Android Design Guideline since at bottom there are soft/hard buttons like back button home button etc.
http://developer.android.com/design/patterns/pure-android.html
But if you insist on to put them at the bottom, you can implement it like GitHub example consists tabs in bottom, using FragmentTabHost.
https://github.com/rameshkec85/BottomTabsFragmentTabHost

These sample xml code defines move tab to bottom of the screen:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TabHost
android:id="#android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<FrameLayout
android:id="#android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="#android:id/tabs" >
<FrameLayout
android:id="#+id/tab_home"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<FrameLayout
android:id="#+id/tab_video"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<FrameLayout
android:id="#+id/tab_audio"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
<FrameLayout
android:id="#+id/tab_blog"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
<FrameLayout
android:id="#+id/tab_gal"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
<FrameLayout
android:id="#+id/tab_more"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
</FrameLayout>
<TabWidget
android:id="#android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true" //align parent bottom mainly used for move the tab to bottom of the screen.
android:background="#drawable/ic_launcher"
android:divider="#null" />
<!-- android:background="#d8e49c" -->
</RelativeLayout>
</TabHost>
</LinearLayout>

with an action bar you will only be able to add tabs at the top, since that is the way android apps should look like. Having tabs at the bottom is purely ios style. and if you still wish to achieve the same look at :
this.
Github source can be found here

Don't do this, tabs should always be at the top in Android.

one more solution: https://stackoverflow.com/a/23150258/2765497
for support api<11 replace TabView to FragmentTabVeiw and add enother imports from Sherlock of Support library

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Fragment (swipe) and Button listener issue - java

final Button button = (Button) rootView.findViewById(R.id.button); b1.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // How to start a new activity form here????? } }); This worked quite well.

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put tabs in the bottom of screen

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