问题，无法在 kotlin recyclerview 上创建生成 toast 消息的事件

Question

我正在使用 Kotlin 创建一个事件，该事件会在单击回收站视图时生成吐司消息。 我在 recyclerview 事件中制作 Tost 消息时遇到了麻烦。 我尝试了以下页面，但无法解决。 Toast 消息在 Recycler 视图中不起作用

错误代码是

in kotlin & None of the following functions can be called with the arguments supplied: public open fun makeText(p0: Context!, p1: CharSequence!, p2: Int): Toast! defined in android.widget.Toast public open fun makeText(p0: Context!, p1: Int, p2: Int): Toast! defined in android.widget.Toast

打印活动.kt

package com.questionbank

class PrintActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val vBinding = ActivityPrintBinding.inflate(layoutInflater)
        setContentView(vBinding.root)
        val helper = SqliteHelper(this, "myDB.sql", 1)

        var recyclerViewAdapter = CustomAdapter()
        recyclerViewAdapter.listData = helper.select()
        vBinding.myRecyclerView.adapter = recyclerViewAdapter
        vBinding.myRecyclerView.layoutManager = LinearLayoutManager(this)
        vBinding.myRecyclerView.addItemDecoration(
            DividerItemDecoration(this, DividerItemDecoration.VERTICAL)

        )

    }

    class CustomAdapter : RecyclerView.Adapter<CustomAdapter.Holder>() {
        var listData = ArrayList<questionType>()

        inner class Holder(val vBinding: QuestionLayoutRecyclerBinding) :
            RecyclerView.ViewHolder(vBinding.root) {
            fun setData(id:Int?, question: String, answer: String, exp: String) {
                vBinding.printId.text=id.toString()

                
                vBinding.myLinear.setOnClickListener {
                    // error occur
                    Toast.makeText(this@PrintActivity, "test", Toast.LENGTH_SHORT).show()
                }

            }
        }

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
            val vBinding = QuestionLayoutRecyclerBinding.inflate(
                LayoutInflater.from(parent.context),
                parent,
                false
            )
            return Holder(vBinding)
        }

        override fun onBindViewHolder(holder: Holder, position: Int) {
            val question = listData[position]
            holder.setData(question.id, question.question, question.answer, question.exp)
        }

        override fun getItemCount(): Int {
            return listData.size
        }

    }

}

活动打印

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".PrintActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/myRecyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="32dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="32dp"
        android:layout_marginBottom="32dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

question_layout_recycler.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/myLinear"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="10dp">

    <TextView
        android:id="@+id/printId"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextView" />

</LinearLayout>

Answer 1

两种修复方法，

1. 将 CustomAdapter class 设为内部 class。

    innner class CustomAdapter: RecyclerView.Adapter<CustomAdapter.Holder>() {

所以祝酒 function 它将从活动 class 中获取常数。

2. 在视图中，从视图中获取上下文。 it.context 将从线性布局中获取上下文。

    vBinding.myLinear.setOnClickListener { Toast.makeText(it.context, "test", Toast.LENGTH_SHORT).show() }

建议将适配器逻辑放在单独的文件中并使用第二种解决方案。 所以你不需要把适配器做成内部 class。