viewpager - tabs android material design

Establecer la pestaña predeterminada para la configuración de Fragment/ViewPager

Question

¿Cómo se establece una pestaña predeterminada cuando se crea FragmentActivity por primera vez? Tengo 5 pestañas y quiero que se abra en la pestaña 2, no en 1. Parece que debería ser mucho más fácil de lo que es.

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_layout);

        mSectionsPagerAdapter = new SectionsPagerAdapter(
                getSupportFragmentManager());

        final ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

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

        mViewPager
                .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
                    @Override
                    public void onPageSelected(int position) {
                        actionBar.setSelectedNavigationItem(position);

                    }
                });

        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            actionBar.addTab(actionBar.newTab()
                    .setText(mSectionsPagerAdapter.getPageTitle(i))
                    .setTabListener(this));
        }


    }

    public void onTabUnselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {

    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
        super.onSaveInstanceState(savedInstanceState);
    }

    @Override
    public void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);

    }

    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
    }

    public void onTabReselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
    }

    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            Fragment f = null;
            switch (position) {
            case 0: {
                f = new MasterFrag();
                Bundle args = new Bundle();

                f.setArguments(args);
                break;
            }


                 // case 1 - 3 edited out; i''d like default view "case 1".

        default:
                throw new IllegalArgumentException("not this many fragments: "
                        + position);
            }

            return f;

        }

        @Override
        public int getCount() {
            return 4;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
            case 0:
                return getString(R.string.mastercattab1).toUpperCase();

                     // case 1- 3 edited out

            }
            return null;
        }
    }

Y mi XML

<?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" >

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

            <TabWidget
                android:id="@android:id/tabs"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="0"
                android:orientation="horizontal" />

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

            <android.support.v4.view.ViewPager
                android:id="@+id/viewpager"
                android:layout_width="fill_parent"
                android:layout_height="0dp"
                android:layout_weight="1" />
        </LinearLayout>
    </TabHost>

</LinearLayout>

Answer 1

¿Has intentado llamar a mViewPager.setCurrentItem(tab.getPosition()); al final de onCreate() ?