Kotlin:如何在Adapter类中调用DialogFragment？

Question

我有一个MainAdapter.kt类来处理RecyclerView.在其Holder类中,我使用OnLongClickListener调用函数deleteCategory(categoryId)来删除Firebase数据库中的条目.这非常有效:

class CategoryHolder(val customView: View, var category: Category? = null) : RecyclerView.ViewHolder(customView) {
    private val TAG = CategoryHolder::class.java.simpleName

    fun bind(category: Category) {
        with(category) {
            customView.textView_name?.text = category.name
            customView.textView_description?.text = category.description

            val categoryId = category.id

            customView.setOnClickListener {
                    // do something
            }

            customView.setOnLongClickListener(
                    {
                       deleteCategory(categoryId)
                       true
                    }
            )
        }
    }

    private fun deleteCategory(categoryId: String) {
        val database = FirebaseDatabase.getInstance()

        val myRef = database.getReference("categories").child(categoryId)
        myRef.removeValue()
        Log.d(TAG, "Category with id " + categoryId + " deleted")
    }
}

但我宁愿调用DialogFragment类中的函数而不是deleteCategory(id)函数,如下所示:

  // Create an instance of a DeleteCategoryDialogFragment and show it
  fun showDeleteCategoryDialog(view: View, categoryId: String) {
      val dialog = DeleteCategoryDialogFragment.newInstance(categoryId)
      dialog.show(this@MainActivity.supportFragmentManager, 
      "DeleteCategoryDialog")
  }

这给了我一个"未解决的参考:@MainActivity"错误.我怎么解决这个问题？有没有办法在我的MainActivity中获取categoryId(String类型)？这将允许我将函数showDeleteCategoryDialog移动到MainActivity并解决问题.

Answer 1

你不能MainActivity在上面提到你的代码.你必须投出context您的ViewHolder是MainActivity使用它之前:

val activity =  itemView.context as? MainActivity
// then you can show your dialog with activity?.supportFragmentManager