从分离的片段中获取上下文？

Question

我正在尝试从分离的片段初始化一个派生自SQLiteOpenHelper 的类DataBaseHandler，该类将context 作为构造函数值。 我已经尝试修复它，就像this 问题中的答案所暗示的那样，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)
    
} 

任何帮助将不胜感激！

Answer 1

你需要在onAttach()里面初始化DatabaseHandler

private lateinit var db2: DataBaseHandler

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