リサイクラービューに表示した画像を押すと画像名をToastで表示させたい


リサイクラービューに表示した画像を押すと画像名をToastで表示させたいのですが、
onCreateViewHolderでview.setOnClickListener(ImageClickListener())を追加すると
Constructor of inner class ImageClickListener can be called only with receiver of containing class
とのエラーが発生してしまいます。
包含クラスのレシーバーでのみ呼び出すことができるとはどういうことなのでしょうか。

MainActivitykt
1import android.os.Bundle
2import android.util.Log
3import android.view.LayoutInflater
4import android.view.View
5import android.view.ViewGroup
6import android.widget.ImageView
7import android.widget.TextView
8import android.widget.Toast
9import androidx.appcompat.app.AppCompatActivity
10import androidx.recyclerview.widget.GridLayoutManager
11import androidx.recyclerview.widget.RecyclerView
12import kotlinx.android.synthetic.main.row.*
13
14
15class MainActivity : AppCompatActivity() {
16
17            lateinit var gAdapter: GazouAdapter
18            lateinit var gGazouList: ArrayList<Gazou>
19
20            override fun onCreate(savedInstanceState: Bundle?) {
21                Log.i("GazouAdapter", "onCreate")
22                super.onCreate(savedInstanceState)
23                setContentView(R.layout.activity_main)
24
25                val map = Gazou("地図",  R.drawable.map_2)
26                val money = Gazou("お金",  R.drawable.money_2)
27                val noimage = Gazou("ノーイメージ",  R.drawable.noimage_2)
28                val refresh = Gazou("リフレッシュ",  R.drawable.refresh_2)
29                val time = Gazou("時間",  R.drawable.time_2)
30                val train = Gazou("電車",  R.drawable.train_2)
31                val img1 = Gazou("画像1",R.drawable.img_1)
32                val map3 = Gazou("画像3",R.drawable.map_3)
33                gGazouList = arrayListOf(map, money, noimage, refresh, time, train, img1, map3)
34
35                val recyclerView = findViewById<RecyclerView>(R.id.lvGazou)
36
37                val layoutManager = GridLayoutManager(this,2)
38                recyclerView.layoutManager = layoutManager
39
40                gAdapter = GazouAdapter(gGazouList)
41                recyclerView.adapter = gAdapter
42
43    }
44    private inner class ImageClickListener : View.OnClickListener {
45        override fun onClick(view: View) {
46            Log.i("GazouAdapter", "onClick")
47            val tvGazouName = view.findViewById<TextView>(R.id.tvGazouName)
48
49            val gazouName = tvGazouName.text.toString()
50            Toast.makeText(applicationContext, gazouName, Toast.LENGTH_SHORT).show()
51        }
52    }
53    class GazouAdapter(private val gazouList: ArrayList<Gazou>): RecyclerView.Adapter<GazouAdapter.ViewHolder>() {
54        class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
55
56            val lvGazouView: ImageView = view.findViewById(R.id.lvGazouView)
57            val tvGazouName: TextView = view.findViewById(R.id.tvGazouName)
58        }
59        override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
60            val view = LayoutInflater.from(viewGroup.context).inflate(R.layout.row, viewGroup, false)
61            Log.i("GazouAdapter", "onCreateViewHolder")
62            //view.setOnClickListener(ItemClickListener())
63
64            view.setOnClickListener(ImageClickListener())
65
66            return ViewHolder(view)
67        }
68        override fun onBindViewHolder(viewHolder: ViewHolder, position: Int) {
69            Log.i("GazouAdapter", "onBindViewHolder")
70            val gazou = gazouList[position]
71
72            viewHolder.lvGazouView.setImageResource(gazou.imageId)
73            viewHolder.tvGazouName.text = gazou.name
74        }
75        override fun getItemCount() = gazouList.size
76    }
77}

rowxml
1<?xml version="1.0" encoding="utf-8"?>
2<LinearLayout
3    xmlns:android="http://schemas.android.com/apk/res/android"
4    android:id="@+id/container"
5    android:orientation="vertical"
6    android:layout_width="match_parent"
7    android:layout_height="match_parent">
8
9    <ImageButton
10        android:id="@+id/lvGazouView"
11        android:layout_width="match_parent"
12        android:layout_height="wrap_content"
13        />
14
15    <TextView
16        android:id="@+id/tvGazouName"
17        android:layout_width="match_parent"
18        android:layout_height="wrap_content"
19        android:layout_marginLeft="10dp"
20        android:layout_marginTop="10dp"
21        android:textSize="18sp" />
22
23
24
25</LinearLayout>

activitymainxml
1<?xml version="1.0" encoding="utf-8"?>
2<LinearLayout
3    xmlns:android="http://schemas.android.com/apk/res/android"
4    xmlns:app="http://schemas.android.com/apk/res-auto"
5    android:layout_width="match_parent"
6    android:layout_height="match_parent">
7
8
9
10    <androidx.recyclerview.widget.RecyclerView
11        android:id="@+id/lvGazou"
12        android:scrollbars="vertical"
13        android:layout_width="match_parent"
14        android:layout_height="match_parent"
15        />
16
17</LinearLayout>

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: jp.co.stv_tech.test2112, PID: 623
    java.lang.RuntimeException: Unable to start activity ComponentInfo{jp.co.stv_tech.test2112/jp.co.stv_tech.test2112.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at jp.co.stv_tech.test2112.MainActivity.onCreate(MainActivity.kt:44)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

行動規範の内容に同意します

回答1件

自己解決

class GazouAdapter(private val gazouList: ArrayList<Gazou>): RecyclerView.Adapter<GazouAdapter.ViewHolder>() {
            class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {

private inner class GazouAdapter(private val gazouList: ArrayList<Gazou>): RecyclerView.Adapter<GazouAdapter.ViewHolder>() {
            inner class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {

innerをつけることで解決しました

投稿2020/06/24 06:21

yu9718s

総合スコア9