[Kotlin] 매개변수가 존재하는 싱글턴 만들기

MainActivity.kt

package com.example.mysingletonpractice

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log

class MainActivity : AppCompatActivity() {
    val TAG: String = "로그"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        Log.d(TAG, "MainActivity - onCreate() called")

        val myNormalClass_1 = MyNormalClass()
        val myNormalClass_2 = MyNormalClass()
        
        Log.d(TAG, "MainActivity myNormalClass_1 : $myNormalClass_1")
        Log.d(TAG, "MainActivity myNormalClass_2 : $myNormalClass_2")

        val mySingleTonClass_1 = MySingletonClass
        val mySingleTonClass_2 = MySingletonClass

        Log.d(TAG, "MainActivity - val mySingleTonClass_1 = $mySingleTonClass_1")
        Log.d(TAG, "MainActivity - val mySingleTonClass_2 = $mySingleTonClass_2")
        
        val mySQLOpenHelper_1 = MySQLOpenHelper(this)
        val mySQLOpenHelper_2 = MySQLOpenHelper(this)
        
        Log.d(TAG, "MainActivity - mySQLOpenHelper_1 : $mySQLOpenHelper_1")
        Log.d(TAG, "MainActivity - mySQLOpenHelper_2 : $mySQLOpenHelper_2")



        val MySQLOpenHelperSingleton_1 = MySQLOpenHelperSingleton.getInstance(this)
        val MySQLOpenHelperSingleton_2 = MySQLOpenHelperSingleton.getInstance(this)

        Log.d(TAG, "MainActivity - MySQLOpenHelperSingleton_1 : $MySQLOpenHelperSingleton_1")
        Log.d(TAG, "MainActivity - MySQLOpenHelperSingleton_2 : $MySQLOpenHelperSingleton_2")


    }
}

 

MySQLOpenHelperSingleton

package com.example.mysingletonpractice

import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper

class MySQLOpenHelperSingleton private constructor(context: Context) : SQLiteOpenHelper(context, "MyDB", null, 1) {
    val TAG = "MySQLOpenHelperSingleton"

    companion object{
        // 자기 자신 변수 선언
        @Volatile private var instance: MySQLOpenHelperSingleton? = null

        // 자기 자신 가져오기
        fun getInstance(context: Context) : MySQLOpenHelperSingleton =
            instance ?: synchronized(this){
                instance ?: MySQLOpenHelperSingleton(context).also{
                    instance = it
                }
            }
    }


    override fun onCreate(p0: SQLiteDatabase?) {
        TODO("Not yet implemented")
    }

    override fun onUpgrade(p0: SQLiteDatabase?, p1: Int, p2: Int) {
        TODO("Not yet implemented")
    }


}