tabstrip with fragment and viewpager problem

[merliniii]

import android.support.design.widget.Snackbar; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.app.FragmentStatePagerAdapter; import android.support.v4.app.FragmentTransaction; import android.support.v4.app.ListFragment; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.support.v7.widget.Toolbar; import android.view.View; import android.view.ViewGroup; import android.widget.FrameLayout; import android.widget.Toast;

import com.gigamole.navigationtabstrip.NavigationTabStrip;

public class MainActivity extends AppCompatActivity {

private NavigationTabStrip mCenterNavigationTabStrip;
private FrameLayout frameLayout;
private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowHomeEnabled(true);

    mCenterNavigationTabStrip = (NavigationTabStrip) findViewById(R.id.nts_center);
    mViewPager = (ViewPager) findViewById(R.id.vp);

    toolbar.setTitleTextColor(G.context.getResources().getColor(R.color.item));
    frameLayout = (FrameLayout) findViewById(R.id.farmlayout);

    setUI();

    mCenterNavigationTabStrip.setViewPager(mViewPager);

            mCenterNavigationTabStrip.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
               //  Toast.makeText(G.context, "positon =" + position, Toast.LENGTH_SHORT).show();
                  mViewPager.setCurrentItem(position);
           // Toast.makeText(G.context, "positon =" + mViewPager.getCurrentItem(), Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

    mCenterNavigationTabStrip.setOnTabStripSelectedIndexListener(new NavigationTabStrip.OnTabStripSelectedIndexListener() {
        @Override
        public void onStartTabSelected(String title, int index) {
            mViewPager.setCurrentItem(index);
            Toast.makeText(G.context, "viewpager  =" + mViewPager.getCurrentItem() + "index  " + index , Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onEndTabSelected(String title, int index) {

        }
    });
}

@Override
public boolean onSupportNavigateUp() {
    onBackPressed();
    return true;
}

private void setUI() {
    mViewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
        @Override
        public Fragment getItem(int position) {
            switch (position) {
                case 0:
                    return new loginFragment();
                case 1:
                    return new signupFragment();
                default:
                    return null;
            }
        }

        @Override
        public int getCount() {
            return 2;
        }
    });

}

}