[Android/Kotlin]RecyclerView 구현

📢리소스 명에 오류가 생길 때
: 소문자로 쓰자!

📢public open fun makeText(p0: Context!, p1: CharSequence!, p2: Int): Toast! defined in android.widget.Toast
this 뒤에 @"Activity이름" 입력

Toast.makeText(this@ContentListActivity, "클릭 성공", Toast.LENGTH_SHORT).show()

-로그출력

Log.d("디버깅용 태그", items.toString())

---

1. RecyclerView가 들어갈 화면 생성

<ContentListActivity\>와 <activity_content_list.xml> 생성

<?xml version="1.0" encoding="utf-8"?>
    <layout>
    <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=".contentsList.ContentListActivity">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ContentListActivity 화면"
            android:textSize="25sp"
            android:textStyle="bold"
            android:textColor="#000000"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:layout_marginTop="20dp"/>


        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/rv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="80dp"/>

        <ImageView
            android:id="@+id/addBtn"
            android:layout_width="150dp"
            android:layout_height="50dp"
            android:src="@drawable/siteadd_button"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginBottom="30dp"/>

    </androidx.constraintlayout.widget.ConstraintLayout>

</layout>

2. RecyclerView 안에 들어갈 xml 생성

<content_rv_item.xml> 생성

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="260dp"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textArea"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:text="Text Area"
        android:textSize="25sp"
        android:textStyle="bold"
        android:background="@drawable/text_stroke"
        android:gravity="center"
        android:layout_gravity="center"/>

    <ImageView
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:layout_gravity="center"
        android:src="@drawable/addplz" />

    <ImageView
        android:src="@drawable/bookmark_white"
        android:layout_marginTop="10dp"
        android:layout_gravity="center"
        android:layout_width="30dp"
        android:layout_height="30dp"/>

</LinearLayout>

3. Adapter에 연결하기

<ContentRVAdpater> 생성

package com.example.recyclerview.contentsList

import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.Adapter
import com.example.recyclerview.R

class ContentRVAdapter(val items : ArrayList<String>) : RecyclerView.Adapter<ContentRVAdapter.Viewholder>() {

    //ViewHolder 객체를 생성하고 초기화
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ContentRVAdapter.Viewholder{
        val v = LayoutInflater.from(parent.context).inflate(R.layout.content_rv_item, parent, false)
        return Viewholder(v)
    }

    //데이터를 가져와 ViewHolder 안의 내용을 채워줌
    override fun onBindViewHolder(holder: ContentRVAdapter.Viewholder, position: Int){
        holder.bindItems(items[position])
    }

    //총 데이터의 개수를 반환해줌
   override fun getItemCount(): Int {
        return items.size
    }

    //item에 있는 내용물을 하나하나 연결해줌
    inner class Viewholder(itemView : View) : RecyclerView.ViewHolder(itemView){

        fun bindItems(item : String){

        }
    }
}

4. <ContentListActivity> 코드 수정

package com.example.recyclerview.contentsList

import android.app.DatePickerDialog
import android.database.DatabaseUtils
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.*
import androidx.appcompat.app.AlertDialog
import androidx.databinding.DataBindingUtil
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.recyclerview.R
import com.example.recyclerview.databinding.ActivityContentListBinding


class ContentListActivity : AppCompatActivity() {

    private lateinit var binding : ActivityContentListBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_content_list)

        binding = DataBindingUtil.setContentView(this, R.layout.activity_content_list)

        val rv : RecyclerView = findViewById(R.id.rv)

        val items = ArrayList<String>()
        
        items.add("a") //임의의 6개 값들을 넣어준 것
        items.add("b")
        items.add("c")
        items.add("c")
        items.add("c")
        items.add("c")

        val rvAdapter = ContentRVAdapter(items)
        rv.adapter = rvAdapter

        rv.layoutManager = GridLayoutManager(this,2)

        //여행지 추가 버튼을 눌렀을 때
        binding.addBtn.setOnClickListener {
            val builder = AlertDialog.Builder(this)

            val dialogView = layoutInflater.inflate(R.layout.custom_dialog, null)
            val dialogSite = dialogView.findViewById<EditText>(R.id.dialogSite)
            val dialogCompanion = dialogView.findViewById<EditText>(R.id.dialogCo)
            
            builder.setView(dialogView)
                .setPositiveButton("확인") { dialogInterface, i ->
                    /* 확인일 때 main의 View의 값에 dialog View에 있는 값을 적용 */
                    Log.d("TAG", dialogSite.text.toString())
                    Log.d("TAG", dialogCompanion.text.toString())
                }
                .setNegativeButton("취소") { dialogInterface, i ->
                    /* 취소일 때 아무 액션이 없으므로 빈칸 */
                }
                .show()
            
        }
    }
}

결과