Fragment-hide和show

private Fragment mContent = new Fragment();// 记录下当前碎片 由于替换
 
private Fragment mPerson;
private Fragment mRanking;
private Fragment mSummary;
private FragmentTransaction transaction;

mPerson = new Personal();
mRanking = new Ranking();
mSummary = new Summary();
fragmentManager = getSupportFragmentManager();
mContent = mRanking;
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.fragment, mContent).commit();
navigation.setSelectedItemId(R.id.navigation_home);

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {
 
    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
                switchContent(mPerson);
                return true;
            case R.id.navigation_dashboard:
                switchContent(mRanking);
                return true;
            case R.id.navigation_ranking:
                switchContent(mSummary);
                return true;
        }
        return false;
    }
};

    private void switchContent(Fragment to) {
        if (mContent != to) {
            FragmentTransaction transaction = fragmentManager.beginTransaction();
            if (!to.isAdded()) { // 判断是否被add过
                // 隐藏当前的fragment，将 下一个fragment 添加进去
                transaction.hide(mContent).add(R.id.fragment, to).commit();
            } else {
                // 隐藏当前的fragment，显示下一个fragment
                transaction.hide(mContent).show(to).commit();
            }
            mContent = to;
        }
 
    }