Android 带浮动操作按钮的底部导航视图

如何创建此Bottomnavigationview？我曾经成功地创建了这个视图，并添加了FloatingActionButton来查看底部的边距。但我认为增加保证金来固定浮动操作按钮的位置是不对的。我想在某些情况下隐藏底部导航和浮动操作按钮，如Recyclerview滚动

在你的主要活动中使用这个

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />

BottomNavigationView的中心项和FloationgActionButton如何？您能提供更多详细信息吗？特别是关于OP关于FAB实施的问题？

BottomNavigationView navigation = findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

    // attaching bottom sheet behaviour - hide / show on scroll
    CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) navigation.getLayoutParams();
    layoutParams.setBehavior(new BottomNavigationBehavior());
    }
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        Fragment fragment;
        switch (item.getItemId()) {
            case R.id.inbox:
                getSupportActionBar().setTitle("Inbox");
                fragment = new OneFragment();
                loadFragment(fragment);
                return true;
            case R.id.terms:
                getSupportActionBar().setTitle("Terms");
                fragment = new TwoFragment();
                loadFragment(fragment);
                return true;
            case R.id.upgrade:
                getSupportActionBar().setTitle("Upgrade Plan");
                fragment = new ThreeFragment();
                loadFragment(fragment);
                return true;
           case R.id.bot:
               getSupportActionBar().setTitle("Buyfie Chatbot");
               fragment = new FourFragment();
               loadFragment(fragment);
               return true;
        }

        return false;
    }
};
private void loadFragment(Fragment fragment) {
    // load fragment
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.frame_container, fragment);
    transaction.addToBackStack(null);
    transaction.commit();
}

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />