theme: apple-basic
layout: intro
highlighter: shiki
lineNumbers: true
public class DBHelper {
private static DBHelper instance;
private DBHelper(){}
public static DBHelper getInstance() {
if(instance == null) {
instance = new DBHelper();
}
return instance;
}
}
object DBHandler {...}
val dbHandler = DBHandler
class DBHandler private constructor(context: Context) {
companion object {
private var instance: DBHandler? = null
fun getInstance(context: Context) =
instance ?: DBHandler(context).also {
instance = it
}
}
}
class DBHandler private constructor(context: Context) {
companion object {
@Volatile
private var instance: DBHandler? = null
fun getInstance(context: Context) =
instance ?: synchronized(DBHelper::class.java) {
instance ?: DBHandler(context).also {
instance = it
}
}
}
}
public class DBHandler {
private DBHandler() {}
private static class Holder{
private static final DBHandler INSTANCE = new DBHandler();
}
public static DBHandler getInstance() {
return Holder.INSTANCE;
}
}
class DBHelper private constructor() {
companion object {
val instance: DBHelper by lazy { Holder.INSTANCE }
}
private object Holder {
val instance = DBHelper()
}
}