片段是一个关键的词。你需要的是片段式的变量。因此，例如，把这种在同一节为mTitle：

Fragment is a key word. What you need is a variable of type Fragment. So, for example, put this in the same section as mTitle:

Fragment mFragment = null; 

在您的switch语句，放，例如：

In your switch statement, put, for example:

mFragment = new Welcome();

然后，当你设置的交易，你可以把：

Then, when you're setting up the transaction, you can put:

fragmentManager.beginTransaction()
   .replace(R.id.container, mFragment)

这可能不会解决所有的问题，但应该让你过去，这些编译错误。

This may not solve all your problems, but should get you past these compilation errors.