Java 21 패턴 매칭 제대로 활용하기(with Scala)

import scala.util.Random

val x: Int = Random.nextInt(10)

x match
  case 0 => "zero"
  case 1 => "one"
  case 2 => "two"
  case _ => "other"

sealed trait Notification

case class Email(sender: String, title: String, body: String) extends Notification
case class SMS(caller: String, message: String) extends Notification
case class VoiceRecording(contactName: String, link: String) extends Notification

def showNotification(notification: Notification): String = {
  notification match {
    case Email(sender, title, _) =>
      s"You got an email from $sender with title: $title"
    case SMS(number, message) =>
      s"You got an SMS from $number! Message: $message"
    case VoiceRecording(name, link) =>
      s"you received a Voice Recording from $name! Click the link to hear it: $link"
  }
}

val someSms = SMS("12345", "Are you there?")
val someVoiceRecording = VoiceRecording("Tom", "voicerecording.org/id/123")

println(showNotification(someSms)) // prints You got an SMS from 12345! Message: Are you there?
println(showNotification(someVoiceRecording)) // prints You received a Voice Recording from Tom! Click the link to hear it: voicerecording.org/id/123

for (NodeFlag flag : source) {
  switch (flag) {
    case NOFLAGS:
      flags.add(Flag.NOFLAGS);
      break;
    case EVENTUAL_FAIL:
      flags.add(Flag.PFAIL);
      break;
    case FAIL:
      flags.add(Flag.FAIL);
      break;
    case HANDSHAKE:
      flags.add(Flag.HANDSHAKE);
      break;
    case MASTER:
      flags.add(Flag.MASTER);
      break;
    case MYSELF:
      flags.add(Flag.MYSELF);
      break;
    case NOADDR:
      flags.add(Flag.NOADDR);
      break;
    case SLAVE:
    case REPLICA:
      flags.add(Flag.REPLICA);
      break;
  }
}

for (NodeFlag flag : source) {
  switch (flag) {
    case NOFLAGS -> flags.add(Flag.NOFLAGS);
    case EVENTUAL_FAIL -> flags.add(Flag.PFAIL);
    case FAIL -> flags.add(Flag.FAIL);
    case HANDSHAKE -> flags.add(Flag.HANDSHAKE);
    case MASTER -> flags.add(Flag.MASTER);
    case MYSELF -> flags.add(Flag.MYSELF);
    case NOADDR -> flags.add(Flag.NOADDR);
    case SLAVE, REPLICA -> flags.add(Flag.REPLICA);
  }
}

switch (returnType) {
  case BOOLEAN:
    return ScriptOutputType.BOOLEAN;
  case MULTI:
    return ScriptOutputType.MULTI;
  case VALUE:
    return ScriptOutputType.VALUE;
  case INTEGER:
    return ScriptOutputType.INTEGER;
  case STATUS:
    return ScriptOutputType.STATUS;
  default:
    throw new IllegalArgumentException("Return type " + returnType + " is not a supported script output type");
}

return switch (returnType) {
  case BOOLEAN -> ScriptOutputType.BOOLEAN;
  case MULTI -> ScriptOutputType.MULTI;
  case VALUE -> ScriptOutputType.VALUE;
  case INTEGER -> ScriptOutputType.INTEGER;
  case STATUS -> ScriptOutputType.STATUS;
  default ->
    throw new IllegalArgumentException("Return type " + returnType + " is not a supported script output type");
};

if (obj instanceof String) {
  String s = (String)obj;
  ... use s ...
}

static String formatter(Object obj) {
    String formatted = "unknown";
    if (obj instanceof Integer i) {
        formatted = String.format("int %d", i);
    } else if (obj instanceof Long l) {
        formatted = String.format("long %d", l);
    } else if (obj instanceof Double d) {
        formatted = String.format("double %f", d);
    } else if (obj instanceof String s) {
        formatted = String.format("String %s", s);
    }
    return formatted;
}

static String formatterPatternSwitch(Object obj) {
    return switch (obj) {
        case Integer i -> String.format("int %d", i);
        case Long l    -> String.format("long %d", l);
        case Double d  -> String.format("double %f", d);
        case String s  -> String.format("String %s", s);
        default        -> obj.toString();
    };
}

record Point(int x, int y) {}

static void printSum(Object obj) {
    if (obj instanceof Point p) {
        int x = p.x();
        int y = p.y();
        System.out.println(x+y);
    }
}

static void printSum(Object obj) {
    if (obj instanceof Point(int x, int y)) {
        System.out.println(x+y);
    }
}

sealed interface Notification {}

record Email(String sender, String title, String body) implements Notification {}
record SMS(String caller, String message) implements Notification {}
record VoiceRecording(String contactName, String link) implements Notification {}

public static String showNotification(Notification notification) {
    return switch (notification) {
        case Email(String sender, String title, String body) ->
            String.format("You got an email from %s with title: %s", sender, title);
        case SMS(String caller, String message) ->
            String.format("You got an SMS from %s! Message: %s", caller, message);
        case VoiceRecording(String contactName, String link) ->
            String.format("You received a Voice Recording from %s! Click the link to hear it: %s", contactName, link);
    };
}

var someSms = new SMS("12345", "Are you there?");
var someVoiceRecording = new VoiceRecording("Tom", "voicerecording.org/id/123");

System.out.println(showNotification(someSms)); // prints You got an SMS from 12345! Message: Are you there?
System.out.println(showNotification(someVoiceRecording)); // prints You received a Voice Recording from Tom! Click the link to hear it: voicerecording.org/id/123

public static String showNotification(Notification notification) {
    return switch (notification) {
        case Email(String sender, String title, _) ->
            STR."You got an email from \{sender} with title: \{title}"; // String interpolation
        case SMS(String caller, String message) ->
            STR."You got an SMS from \{caller}! Message: \{message}";
        case VoiceRecording(String contactName, String link) ->
            STR."You received a Voice Recording from \{contactName}! Click the link to hear it: \{link}";
    };
}