ViewPager

BaseFragment

public abstract class BaseFragment extends Fragment {
    private boolean isCreate = false;
    private Activity activity;
    private View mView;

    public Context getContext() {
        if (activity == null) 
            return App.getInstance();
        return activity;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        isCreate = true;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        activity = getActivity();
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(setLayout(), container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mView = view;
        setPresenter();
        setBinding(view);
        if (savedInstanceState == null) {
            initEventAndData();
        }
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        if(isVisibleToUser && isCreate) {
            setBinding(mView);
            initEventAndData();
        }
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }

    protected abstract int setLayout();

    protected abstract void setPresenter();

    protected abstract void setBinding(View view);

    protected abstract void initEventAndData();

    protected void hint(String msg) {
        SnackBarUtil.showShort(((Activity) getContext()).getWindow().getDecorView(), msg);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:fitsSystemWindows="true">

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

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="44dp"
            android:background="@color/colorLT_bg">

            <TextView
                android:id="@+id/tv_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="@string/title"
                android:textColor="@color/colorLT_title"
                android:textSize="20sp"/>

            <ImageView
                android:id="@+id/iv_setting"
                android:layout_width="50dp"
                android:layout_height="match_parent"
                android:layout_alignParentEnd="true"
                android:padding="7dp"
                android:src="@drawable/set_icon"/>

        </RelativeLayout>

        <android.support.v4.view.ViewPager
            android:id="@+id/vp_main"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"/>

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="2px"
            android:background="@color/colorLT_text"/>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:layout_marginBottom="5dp"
            android:layout_marginTop="5dp">

            <LinearLayout
                android:id="@+id/ll_search"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <ImageView
                    android:id="@+id/iv_search"
                    android:layout_width="wrap_content"
                    android:layout_height="30dp"
                    android:src="@drawable/wechat_p"/>

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="搜索"/>

            </LinearLayout>

            <LinearLayout
                android:id="@+id/ll_bill"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <ImageView
                    android:id="@+id/iv_bill"
                    android:layout_width="match_parent"
                    android:layout_height="30dp"
                    android:src="@drawable/people"/>

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="钱包"/>

            </LinearLayout>

            <LinearLayout
                android:id="@+id/ll_statistics"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <ImageView
                    android:id="@+id/iv_statistics"
                    android:layout_width="match_parent"
                    android:layout_height="30dp"
                    android:src="@drawable/find"/>

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="统计"/>

            </LinearLayout>

        </LinearLayout>

    </LinearLayout>

</layout>

FragmentPagerAdapter

public class FragmentPagerAdapter extends FragmentStatePagerAdapter {
    private List<Fragment> fragments;

    public FragmentPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
        super(fm);
        this.fragments = fragments;
    }

    @Override
    public Fragment getItem(int position) {
        return fragments.get(position);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }
}

SearchFragment

public class SearchFragment extends BaseFragment implements SearchContract.View {
    private SearchPresenter mPresenter;
    private FragmentSearchBinding mBinding;

    @Override
    protected void setPresenter() {
        mPresenter = new SearchPresenter(this);
    }

    @Override
    protected int setLayout() {
        return R.layout.fragment_search;
    }

    @Override
    protected void setBinding(View view) {
        mBinding = DataBindingUtil.bind(view);
    }

    @Override
    protected void initEventAndData() {
    }
}

MainActivity

private void initViewPager() {
    List<Fragment> fragments = new ArrayList<>();
    fragments.add(new SearchFragment());
    fragments.add(new BillFragment());
    fragments.add(new StatisticsFragment());

    FragmentPagerAdapter fragmentPagerAdapter = new FragmentPagerAdapter(getSupportFragmentManager(), fragments);
    mBinding.vpMain.setAdapter(fragmentPagerAdapter);
    mBinding.vpMain.setOffscreenPageLimit(2);
    mBinding.vpMain.setCurrentItem(0);
    mBinding.vpMain.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        @Override
        public void onPageSelected(int position) {
            switch (position) {
                case 0:
                    mBinding.ivSearch.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.wechat_p));  
                    mBinding.ivBill.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.people));
                    mBinding.ivStatistics.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.find));
                    break;
                case 1:
                    mBinding.ivSearch.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.wechat));
                    mBinding.ivBill.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.people_p));
                    mBinding.ivStatistics.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.find));
                    break;
                case 2:
                    mBinding.ivSearch.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.wechat));
                    mBinding.ivBill.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.people));
                    mBinding.ivStatistics.setImageDrawable(ContextCompat.getDrawable(MainActivity.this, R.drawable.find_p));
                    break;
            }
        }

        @Override
        public void onPageScrollStateChanged(int state) {
        }
    });
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.iv_setting:
            PreferenceActivity.actionStart(this);
            break;
        case R.id.ll_search:
            mBinding.vpMain.setCurrentItem(0);
            break;
        case R.id.ll_bill:
            mBinding.vpMain.setCurrentItem(1);
            break;
        case R.id.ll_statistics:
            mBinding.vpMain.setCurrentItem(2);
            break;
    }
}