= new ParentFragment(); fragmentTransaction.add(R.id.main_fragment_container= new ChildFragment(); fragmentTransaction.add(R.id.parent_fragment_container, childFragment).commit();问题是,ChildFragment
getActivity()是什么意思?我在某处看到他们写的是MainActivity.this.startActionMode(mActionModeCallback)而不是getActivity()。谁能解释一下这两行是什么意思? // Called when the user long-clicks on someView