加入back stack.代码如下:
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction =
fragmentManager.beginTransaction();
// 创建Fragment2
Fragment2 fragment2 = new Fragment2();
// 替换Fragment
fragmentTransaction.replace(
R.id.fragmentcontainer, fragment2);
// 加入back stack:============================就是下面这行。
fragmentTransaction.addToBackStack(null);
// 提交事务
fragmentTransaction.commit();