Tabs execute the codes present in their next fragments in android

Question

I am trying to implement Tabs with swipe using ViewPager and 4 Fragments. When I swipe the tabs the respective xml layouts of the fragmnets are displayed correctly on each tab but the code of the fragments are not executed correctly. eg-The following tabs have the respective fragments in it.

Tab0-ButtonFragment

public class ButtonFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_button, container, false);
    Log.i("inside", "button fragment");
    return rootView;
}

Tab1-ImageFragment

public class ImageFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_image, container, false);
    Log.i("inside", "image fragment");
    return rootView;
}

Tab2-TextFragment

    public class TextFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_text, container, false);
    Log.i("inside", "text fragment");
    return rootView;
}

Tab3-Test public class Test extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.temp, container, false);
    Log.i("inside", "tessssssssst fragment");
    return rootView;
}

When the tabs are displayed I get the log message for tab0 and tab1 simultaneously. Then after swiping and going to tab1 i get the log message for tab2. After swiping to tab2 i get log message for tab 3 and when tab 3 is reached no log message is dispalyed. Can anyone tell me how can I execute the respective codes for the respective tabs? My remaining codes are as below:

public class TabsPagerAdapter extends FragmentPagerAdapter { //Update - code formatting

public TabsPagerAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem( int index) {
    Log.i("index", "" + index);
    switch (index) {
    case 0:
        // Top Rated fragment activity
        return new ButtonFragment();
    case 1:
        // Games fragment activity
        return new ImageFragment();
    case 2:
        // Movies fragment activity
        return new TextFragment();
    case 3:
        return new Test();
    }

    return null;
}

@Override
public int getCount() {
    // get item count - equal to number of tabs
    return 4;
}

MainActivity

       public class MainActivity extends FragmentActivity implements OnTabChangeListener, OnPageChangeListener {

private TabsPagerAdapter mAdapter;
private ViewPager mViewPager;
private TabHost mTabHost;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mViewPager = (ViewPager) findViewById(R.id.viewpager);

    // Tab Initialization
    initialiseTabHost();
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
    // Fragments and ViewPager Initialization


    mViewPager.setAdapter(mAdapter);
    mViewPager.setOnPageChangeListener(MainActivity.this);
}

// Method to add a TabHost
private static void AddTab(MainActivity activity, TabHost tabHost, TabHost.TabSpec tabSpec) {
    tabSpec.setContent(new MyTabFactory(activity));
    tabHost.addTab(tabSpec);
}

// Manages the Tab changes, synchronizing it with Pages
public void onTabChanged(String tag) {
    int pos = this.mTabHost.getCurrentTab();
    this.mViewPager.setCurrentItem(pos);
}

@Override
public void onPageScrollStateChanged(int arg0) {
}

// Manages the Page changes, synchronizing it with Tabs
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
    int pos = this.mViewPager.getCurrentItem();
    this.mTabHost.setCurrentTab(pos);
}

@Override
    public void onPageSelected(int arg0) {

}


// Tabs Creation
private void initialiseTabHost() {
    mTabHost = (TabHost) findViewById(android.R.id.tabhost);
    mTabHost.setup();

    // TODO Put here your Tabs
    MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("ButtonTab").setIndicator("ButtonTab"));
    MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("ImageTab").setIndicator("ImageTab"));
    MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("TextTab").setIndicator("TextTab"));
    MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("TestingTab").setIndicator("TestingTab"));

    mTabHost.setOnTabChangedListener(this);
}

Answer 1

This is default behaviour of viewpager you can not change it as viewpager creates fragments so that the views exist, so the user can swipe between them, so that the old view sliding off the screen and the new view sliding onto the screen. You can write your code like this

 @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        if (isVisibleToUser) {
          Log.i("inside", "button fragment");
        }else{
           // fragment is not visible
        }
    } 

so that when fragment is visible your code execute

Answer 2

When change your tab recall your corresponding fragment. Try this it will help you

Create TabFragment.java

public class TabFragment extends Fragment implements OnPageChangeListener,
    OnTabChangeListener {
private TabHost tabHost;
private int currentTab = 0;
private SwipeDisableViewPager viewPager;
protected TabPagerAdapter pageAdapter;
private List<Fragment> fragments;
private final int TAB_BUTTON=0,TAB_IMAGE=1,TAB_TEXT=2,TAB_TEST=3;

@SuppressWarnings("unchecked")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.activity_tabhost, null);
    viewPager = (SwipeDisableViewPager) view.findViewById(R.id.viewpager);
    tabHost = (TabHost) view.findViewById(android.R.id.tabhost);
    viewPager.addOnPageChangeListener(this);
    fragments = new ArrayList<>();
    fragments.add(new ButtonFragment());
    fragments.add(new ImageFragment());
    fragments.add(new TextFragment());
    fragments.add(new Test());
    return view;
}


@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    pageAdapter = new TabPagerAdapter(getChildFragmentManager(), fragments, getArguments());
    pageAdapter.notifyDataSetChanged();
    viewPager.setAdapter(pageAdapter);
    viewPager.setOffscreenPageLimit(3);
    setupTabs();
}


private void setupTabs() {
    tabHost.setup();
    tabHost.addTab(newTab(R.string.home, R.drawable.menu_home_bg));
    tabHost.addTab(newTab(R.string.likes, R.drawable.menu_likes_bg));
    tabHost.addTab(newTab(R.string.matches, R.drawable.menu_matches_bg));
    for (int i = 0; i < tabHost.getTabWidget().getChildCount(); i++) {
        tabHost.getTabWidget().setShowDividers(LinearLayout.SHOW_DIVIDER_NONE);

    }
    tabHost.setOnTabChangedListener(this);
    tabHost.setCurrentTab(currentTab);
}

private View getTabIndicator(Context context, int title, int icon) {
    View view = LayoutInflater.from(context).inflate(R.layout.tab_view, null);
    ImageView iv = (ImageView) view.findViewById(R.id.imageView);
    iv.setImageResource(icon);
    TextView tv = (TextView) view.findViewById(R.id.textView);
    tv.setText(title);
    return view;
}

private TabSpec newTab(int tabValue, int icon) {
    TabSpec tabSpec = tabHost.newTabSpec(getString(tabValue));
    tabSpec.setIndicator(getTabIndicator(tabHost.getContext(), tabValue, icon));
    tabSpec.setContent(new Dummy(getActivity()));
    return tabSpec;
}

@Override
public void onPageScrollStateChanged(int arg0) {

}

@Override
public void onPageScrolled(int currentPosition, float arg1, int arg2) {

}

@Override
public void onPageSelected(int position) {
    if (position == 0)
        viewPager.setSwipeEnabled(false);
    else
        viewPager.setSwipeEnabled(true);
    tabHost.setCurrentTab(position);
    if (listener != null)
        listener.onTabChanged(position);
}

@Override
public void onTabChanged(String tabId) {
    currentTab = tabHost.getCurrentTab();
    viewPager.setCurrentItem(currentTab);
    switch(currentTab){
      case TAB_BUTTON:
        ((ButtonFragment) fragments.get(currentTab)).recall();
      break;
      case TAB_IMAGE:
        ((ImageFragment) fragments.get(currentTab)).recall();
      break;
      case TAB_TEXT:
        ((TextFragment) fragments.get(currentTab)).recall();
      break;
      case TAB_TEST:
        ((Test) fragments.get(currentTab)).recall();
      break;        
}
}

create tab_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <TabWidget
        android:id="@android:id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:background="@drawable/menu_bg"
        android:fadingEdge="none"
        android:gravity="center"
        android:showDividers="none"
        android:tabStripEnabled="false" />

    <FrameLayout
        android:id="@android:id/tabcontent"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_weight="0" />

    <com.mobellotech.shift.Widget.SwipeDisableViewPager
        android:id="@+id/viewpager"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:background="#FFFFFF" />
</LinearLayout>
</TabHost>

Create tab_view.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">

<ImageView
    android:id="@+id/imageView"
    android:layout_width="45dp"
android:layout_height="45dp"
    android:contentDescription="@string/menu_icon" />

<TextView
    android:id="@+id/textView"
     android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>

Create TabPagerAdaper

public class TabPagerAdapter extends FragmentPagerAdapter {
private Bundle args;
private List<Fragment> fragments;

public TabPagerAdapter(FragmentManager fm, List<Fragment> fragments,
                       Bundle args) {
    super(fm);
    this.fragments = fragments;
    this.args = args;
}

@Override
public Fragment getItem(int position) {
    Fragment fragment = fragments.get(position);
    fragment.setArguments(args);
    return fragment;
}

@Override
public int getCount() {
    return fragments.size();
}

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}
}

Create MainActivity.java

public class MainActivity extends AppCompatActivity  {

protected TabFragment tabFragment;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tabFragment = new TabFragment();
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction().replace(R.id.frame_container, tabFragment).commit();
}
}

Create activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/DrawerLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
    <FrameLayout
        android:id="@+id/frame_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
      />
</android.support.v4.widget.DrawerLayout>

Finally add the recall method in your fragment class like this

public class ButtonFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {

View rootView = inflater.inflate(R.layout.fragment_button, container, false);
Log.i("inside", "button fragment");
return rootView;
}
 public void recall() {
     Log.i("inside", "button fragment");
 }
}