How to refresh a fragment in a viewpager?

Question

I know there are already some questions to this problem. But I am really new in Android and ecspecially to Fragments and Viewpager. Pls have passion with me. I didn't found a answer which fits to my code.

I dont know how to refresh a fragment or reload it when it's "active" again.

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 KFZFragment();
        case 1:

            return new LogFragment();
        case 2:

            return new TrackFragment();
        }

        return null;
    }

    @Override
    public int getCount() {
        // get item count - equal to number of tabs
        return 3;
    }

}

I have this 3 Fragments (KFZFragment,LogFragment,TrackFragment) and on the TrackFragment I calculate some data and this data should be display in a ListView in LogFragment. But when I change to LogFragment it's not the latest data. So it doesnt refresh.

Now how should I modify my code to refresh the fragments when it's "active"?

MainActivityFragment.java:

public class MainActivityFragment extends FragmentActivity implements ActionBar.TabListener{

    private ViewPager viewPager;
    private TabsPagerAdapter mAdapter;
    private ActionBar actionBar;
    List<Fragment> fragments;

    private String[] tabs = { "KFZ", "Fahrten Log", "Kosten Track" };

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

        // Initilization
        viewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
        mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

       fragments = new Vector<Fragment>();
        fragments.add(Fragment.instantiate(this, KFZFragment.class.getName(),savedInstanceState));
        fragments.add(Fragment.instantiate(this, LogFragment.class.getName(),savedInstanceState));

        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));
        }

        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) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        viewPager.setCurrentItem(tab.getPosition());

    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {


        }
        return super.onKeyDown(keyCode, event);
    }

}

Pls help me out.

Solution

In each of your KFZFragment, LogFragment, and TrackFragment, you should be able to override onResume in your fragment class and put your necessary refresh/reload code there.

Comments

[cYrixmorten]

Could be dangerous if the fragment is currently not 'alive' e.g. during orientation change or the like.