从分离的片段中获取上下文？

Question

我正在尝试从一个分离的片段中初始化一个从 SQLiteOpenHelper 派生的 class DataBaseHandler，它将 context 作为构造函数值。 我试过按照 this 问题中的答案修复它，但是 override fun onAttach() 没有被调用。我的代码：

class CustomFragment : Fragment() {

    /* first attempt to initialize DBHandler. I get an exception saying the fragment is not 
       attached to the context */
    private var db1: DataBaseHandler = DataBaseHandler(requireContext())

    // variables for second attempt to initialize DBHandler (after onAttach)
    private lateinit var fragmentContext: Context
    private lateinit var db2: DataBaseHandler

    override fun onAttach(context: Context) {
        super.onAttach(context)
        fragmentContext = context
    }
    
    // I get an exception, saying that context is not initialized
    db2 = DataBaseHandler(context)
    
} 

如有任何帮助，我们将不胜感激！

Answer 1

您需要在 onAttach()

中初始化 DatabaseHandler

private lateinit var db2: DataBaseHandler

override fun onAttach(context: Context) {
    super.onAttach(context)
    db2 = DataBaseHandler(context)
}