Question

My app has progressed enough to start testing it out on a variety of devices. Now, I would like for people sub 3.0 to be able to use my app. Granted, I am using the compatibility library with the standard actionbar, which obviously crashes the app as soon as it starts when the SDK version is 10 or lower, as expected. I understand that I could use the ABS library, but my concern is my customized ViewPager and TabAdapter. Here’s the code:

public class Polling extends FragmentActivity {
    private ViewPager mViewPager;
    private TabsAdapter mTabsAdapter;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //sharedPreferences = getPreferences(MODE_PRIVATE);
        mViewPager = new ViewPager(this);
        mViewPager.setId(R.id.pager);
        setContentView(mViewPager);
        final ActionBar bar = getActionBar();
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        bar.setDisplayShowTitleEnabled(false);
        bar.setDisplayShowHomeEnabled(false);

        mTabsAdapter = new TabsAdapter(this, mViewPager);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.login),
                LoginFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.economics),
                EconFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.elections),
                ElectionsFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.politics),
                PoliticsFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.science),
                ScienceFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.finance),
                FinanceFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.religion),
                ReligionFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.military),
                MilitaryFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(R.string.international),
                InternationalFragment.class, null); 


    }

public static class TabsAdapter extends FragmentPagerAdapter
    implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
        private final Context mContext;
        private final ActionBar mActionBar;
        private final ViewPager mViewPager;
        private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

        static final class TabInfo {
            private final Class<?> clss;
            private final Bundle args;

            TabInfo(Class<?> _class, Bundle _args) {
                clss = _class;
                args = _args;
            }
        }

        public TabsAdapter(FragmentActivity activity, ViewPager pager) {
            super(activity.getSupportFragmentManager());
            mContext = activity;
            mActionBar = activity.getActionBar();
            mViewPager = pager;
            mViewPager.setAdapter(this);
            mViewPager.setOnPageChangeListener(this);
        }

        public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
            TabInfo info = new TabInfo(clss, args);
            tab.setTag(info);
            tab.setTabListener(this);
            mTabs.add(info);
            mActionBar.addTab(tab);
            notifyDataSetChanged();
        }


        public int getCount() {
            return mTabs.size();
        }

        public Fragment getItem(int position) {
            TabInfo info = mTabs.get(position);
            return Fragment.instantiate(mContext, info.clss.getName(), info.args);
        }


        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }


        public void onPageSelected(int position) {
            mActionBar.setSelectedNavigationItem(position);
        }


        public void onPageScrollStateChanged(int state) {
        }


        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            mViewPager.setCurrentItem(tab.getPosition());
            Log.v(TAG, "clicked");
            Object tag = tab.getTag();
            for (int i=0; i<mTabs.size(); i++) {
                if (mTabs.get(i) == tag) {
                    mViewPager.setCurrentItem(i);
                }
            }
        }

        public void onTabUnselected(Tab tab, FragmentTransaction ft) {}

        public void onTabReselected(Tab tab, FragmentTransaction ft) {}

        public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {}

        @Override
        public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {    
            Object tag = tab.getTag();
            for (int i=0; i<mTabs.size(); i++) {
                if (mTabs.get(i) == tag) {
                    mViewPager.setCurrentItem(i);
                }
            }
        }

        public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {}
    }

Should I just say screw backwards compatibility? I mean, that’s a lot of potential installs that I lose by saying you can’t use the app if it’s Gingerbread or lower.

Answer 1

With ActionBarSherlock you can support Android 2.1 and newer with extremely simple replacements in your code.

1. Change getActionBar to getSupportActionBar
2. Change all menu-related imports to use com.actionbarsherlock.view.* rather than android.view.*.
3. Change all fragment-related imports to use android.support.v4.app.* rather than android.app.*.
4. Extend SherlockFragmentActivity rather than Activity.
5. Use Theme.Sherlock (or another ABS theme) in your manifest.

That should be all that is necessary to get a functioning app that looks identical on all platforms!

If you need more help be sure to check out the following resources:

• Website: http://actionbarsherlock.com
• Google Group: http://abs.io/forum
• StackOverflow tag: https://stackoverflow.com/questions/tagged/actionbarsherlock
• GitHub repository: http://abs.io/github