TabActivity -> Fragments.. is it really this complicated?

Question

I know the tabactivity thing has been covered here a million times, by ten million people. I've got the developer references and have been reading all the threads I can find on SO. My question is though, is fragments REALLY that complicated? From what I can gather, it seems to be, whereas TabActivty was so easy. See example below:

My current code, required for four tabs, looks like this:

Resources res = getResources(); // Resource object to get Drawables
        TabHost tabHost = getTabHost(); // The activity TabHost
        TabHost.TabSpec spec; // Resusable TabSpec for each tab
        Intent intent; // Reusable Intent for each tab

        // Create an Intent to launch an Activity for the tab (to be reused)
        intent = new Intent().setClass(this, ServerActivity.class);

        // Initialize a TabSpec for each tab and add it to the TabHost
        spec = tabHost
                .newTabSpec("server")
                .setIndicator("Server",
                        res.getDrawable(R.drawable.ic_tab_server))
                .setContent(intent);
        tabHost.addTab(spec);

        // Do the same for the other tabs
        intent = new Intent().setClass(this, StatusActivity.class);
        spec = tabHost
                .newTabSpec("status")
                .setIndicator("Status",
                        res.getDrawable(R.drawable.ic_tab_status))
                .setContent(intent);
        tabHost.addTab(spec);

        intent = new Intent().setClass(this, LoggingActivity.class);
        spec = tabHost
                .newTabSpec("logging")
                .setIndicator("Logs",
                        res.getDrawable(R.drawable.ic_tab_logging))
                .setContent(intent);
        tabHost.addTab(spec);

        intent = new Intent().setClass(this, DeliveryActivity.class);
        spec = tabHost
                .newTabSpec("deliveryqueue")
                .setIndicator("Queue", res.getDrawable(R.drawable.ic_tab_queue))
                // .setIndicator("Delivery Queue",
                // res.getDrawable(R.drawable.ic_tab_artists))
                .setContent(intent);
        tabHost.addTab(spec);

        tabHost.setCurrentTab(2);
    }

According to the developers reference, for the equivelent of 4 tabs, you need ALL this:

    import java.util.HashMap;

import com.example.android.supportv4.R;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.TabHost;

/**
 * This demonstrates how you can implement switching between the tabs of a
 * TabHost through fragments.  It uses a trick (see the code below) to allow
 * the tabs to switch between fragments instead of simple views.
 */
public class FragmentTabs extends FragmentActivity {
    TabHost mTabHost;
    TabManager mTabManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.fragment_tabs);
        mTabHost = (TabHost)findViewById(android.R.id.tabhost);
        mTabHost.setup();

        mTabManager = new TabManager(this, mTabHost, R.id.realtabcontent);

        mTabManager.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"),
                FragmentStackSupport.CountingFragment.class, null);
        mTabManager.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"),
                LoaderCursorSupport.CursorLoaderListFragment.class, null);
        mTabManager.addTab(mTabHost.newTabSpec("custom").setIndicator("Custom"),
                LoaderCustomSupport.AppListFragment.class, null);
        mTabManager.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"),
                LoaderThrottleSupport.ThrottledLoaderListFragment.class, null);

        if (savedInstanceState != null) {
            mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab"));
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putString("tab", mTabHost.getCurrentTabTag());
    }

    /**
     * This is a helper class that implements a generic mechanism for
     * associating fragments with the tabs in a tab host.  It relies on a
     * trick.  Normally a tab host has a simple API for supplying a View or
     * Intent that each tab will show.  This is not sufficient for switching
     * between fragments.  So instead we make the content part of the tab host
     * 0dp high (it is not shown) and the TabManager supplies its own dummy
     * view to show as the tab content.  It listens to changes in tabs, and takes
     * care of switch to the correct fragment shown in a separate content area
     * whenever the selected tab changes.
     */
    public static class TabManager implements TabHost.OnTabChangeListener {
        private final FragmentActivity mActivity;
        private final TabHost mTabHost;
        private final int mContainerId;
        private final HashMap<String, TabInfo> mTabs = new HashMap<String, TabInfo>();
        TabInfo mLastTab;

        static final class TabInfo {
            private final String tag;
            private final Class<?> clss;
            private final Bundle args;
            private Fragment fragment;

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

        static class DummyTabFactory implements TabHost.TabContentFactory {
            private final Context mContext;

            public DummyTabFactory(Context context) {
                mContext = context;
            }

            @Override
            public View createTabContent(String tag) {
                View v = new View(mContext);
                v.setMinimumWidth(0);
                v.setMinimumHeight(0);
                return v;
            }
        }

        public TabManager(FragmentActivity activity, TabHost tabHost, int containerId) {
            mActivity = activity;
            mTabHost = tabHost;
            mContainerId = containerId;
            mTabHost.setOnTabChangedListener(this);
        }

        public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
            tabSpec.setContent(new DummyTabFactory(mActivity));
            String tag = tabSpec.getTag();

            TabInfo info = new TabInfo(tag, clss, args);

            // Check to see if we already have a fragment for this tab, probably
            // from a previously saved state.  If so, deactivate it, because our
            // initial state is that a tab isn't shown.
            info.fragment = mActivity.getSupportFragmentManager().findFragmentByTag(tag);
            if (info.fragment != null && !info.fragment.isDetached()) {
                FragmentTransaction ft = mActivity.getSupportFragmentManager().beginTransaction();
                ft.detach(info.fragment);
                ft.commit();
            }

            mTabs.put(tag, info);
            mTabHost.addTab(tabSpec);
        }

        @Override
        public void onTabChanged(String tabId) {
            TabInfo newTab = mTabs.get(tabId);
            if (mLastTab != newTab) {
                FragmentTransaction ft = mActivity.getSupportFragmentManager().beginTransaction();
                if (mLastTab != null) {
                    if (mLastTab.fragment != null) {
                        ft.detach(mLastTab.fragment);
                    }
                }
                if (newTab != null) {
                    if (newTab.fragment == null) {
                        newTab.fragment = Fragment.instantiate(mActivity,
                                newTab.clss.getName(), newTab.args);
                        ft.add(mContainerId, newTab.fragment, newTab.tag);
                    } else {
                        ft.attach(newTab.fragment);
                    }
                }

                mLastTab = newTab;
                ft.commit();
                mActivity.getSupportFragmentManager().executePendingTransactions();
            }
        }
    }
}

Is it REALLY that complex? it's like two - three times the amount of code to complete the same thing. I really want to stay away from using deprecated methods, but wow.

Answer 1

The developer document's solution is around 100 lines of additional code (plus a view replacement). The solution provided isn't particularly complex, and extendable in an obvious location (onTabChanged) if you want to trigger an action when the tab is changed. I wouldn't shy away from using it as it will obtain the results you so desire. I was moving from an ActionBar to TabHost and found it to be a drop-in replacement for my existing fragments management.