replace

private  void  LoandFragment(Fragment fragment){        FragmentManager fm = getSupportFragmentManager();        FragmentTransaction ft = fm.beginTransaction();        ft.replace(R.id.fragment, fragment);        ft.commitAllowingStateLoss();    }

add

private Fragment currentFragment = new Fragment();    //Fragment优化    private FragmentTransaction transaction(Fragment targetFragment) {        FragmentTransaction transaction = getSupportFragmentManager()                .beginTransaction();        if (!targetFragment.isAdded()) {            //第一次使用switchFragment()时currentFragment为null，所以要判断一下            if (currentFragment != null) {                transaction.hide(currentFragment);            }            transaction.add(R.id.fragment, targetFragment, targetFragment.getClass().getName());        } else {            transaction                    .hide(currentFragment)                    .show(targetFragment);        }        currentFragment = targetFragment;        return transaction;    }

性能没什么区别～～～