Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Why don't you use enum ?
Search
Masayuki Izumi
August 11, 2015
Technology
2
3.4k
Why don't you use enum ?
【第20回】potatotips(iOS/Android開発Tips共有会) 発表資料
http://connpass.com/event/17624/
Masayuki Izumi
August 11, 2015
Tweet
Share
More Decks by Masayuki Izumi
See All by Masayuki Izumi
TypeScript を活かしてデザインシステム MCP を作る / #tskaigi_after_night
izumin5210
5
690
複雑なフォームを継続的に開発していくための技術選定・設計・実装 #tskaigi / #tskaigi2025
izumin5210
12
8.6k
複雑なフォームの jotai 設計 / Designing jotai(state) for Complex Forms #layerx_frontend
izumin5210
8
3.3k
複雑なフォームと複雑な状態管理にどう向き合うか / #newt_techtalk vol. 15
izumin5210
4
4.6k
よくできたテンプレート言語として TypeScript + JSX を利用する試み / Using TypeScript + JSX outside of Web Frontend #TSKaigiKansai
izumin5210
9
5.7k
WebフロントエンドにおけるGraphQL(あるいはバックエンドのAPI)との向き合い方 / #241106_plk_frontend
izumin5210
5
1.9k
connect-go で面倒くささと戦う / 2024-08-27 #newmo_layerx_go
izumin5210
2
1.5k
コンパウンドプロダクト開発の質とスピードを支える Protobuf と Connect #アーキテクチャ_findy / Boosting Compound Product Development Efficiency with Protobuf and Connect
izumin5210
13
4.5k
GraphQLサーバの構成要素を整理する #ハッカー鮨 #tsukijigraphql / graphql server technology selection
izumin5210
5
1.4k
Other Decks in Technology
See All in Technology
Platform開発が先行する Platform Engineeringの違和感
kintotechdev
4
540
ハードウェアとソフトウェアをつなぐ全てを内製している企業の E2E テストの作り方 / How to create E2E tests for a company that builds everything connecting hardware and software in-house
bitkey
PRO
1
120
Agile PBL at New Grads Trainings
kawaguti
PRO
1
390
生成AI時代のデータ基盤設計〜ペースレイヤリングで実現する高速開発と持続性〜 / Levtech Meetup_Session_2
sansan_randd
1
150
エラーとアクセシビリティ
schktjm
1
1.2k
フィンテック養成勉強会#56
finengine
0
140
オブザーバビリティが広げる AIOps の世界 / The World of AIOps Expanded by Observability
aoto
PRO
0
340
「どこから読む?」コードとカルチャーに最速で馴染むための実践ガイド
zozotech
PRO
0
280
バッチ処理で悩むバックエンドエンジニアに捧げるAWS Glue入門
diggymo
3
190
新アイテムをどう使っていくか?みんなであーだこーだ言ってみよう / 20250911-rpi-jam-tokyo
akkiesoft
0
150
実践!カスタムインストラクション&スラッシュコマンド
puku0x
0
340
CDK CLIで使ってたあの機能、CDK Toolkit Libraryではどうやるの?
smt7174
4
100
Featured
See All Featured
How STYLIGHT went responsive
nonsquared
100
5.8k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
252
21k
StorybookのUI Testing Handbookを読んだ
zakiyama
31
6.1k
Context Engineering - Making Every Token Count
addyosmani
1
29
[RailsConf 2023] Rails as a piece of cake
palkan
57
5.8k
10 Git Anti Patterns You Should be Aware of
lemiorhan
PRO
656
61k
Optimizing for Happiness
mojombo
379
70k
The Power of CSS Pseudo Elements
geoffreycrofte
77
6k
Being A Developer After 40
akosma
90
590k
A Tale of Four Properties
chriscoyier
160
23k
A designer walks into a library…
pauljervisheath
207
24k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
30
9.6k
Transcript
Why don’t you use enum ? Masayuki IZUMI - @izumin5210
potatotips #20
Ƅ Rekimoto Lab. at the University of Tokyo (2008-2015: Akashi-NCT)
Ɠ Enginner at Wantedly, Inc. (2014.9-2015.2: Dmetlabel, Inc.) 2
2 Ruby JavaScript Android Design pry(main) > izumin.skill_ratio
Enum
Enum as constants public class Status { public static final
int OK = 0; public static final int ERROR = -1; }
public enum Status { OK, ERROR; } public class Status
{ public static final int OK = 0; public static final int ERROR = -1; } Enum as constants
Example - Enum as constants public void onSomethingAction(int status) {
switch (status) { case Status.OK: Log.d(TAG, "status: OK"); break; case Status.ERROR: Log.d(TAG, "status: ERROR"); break; } }
Example - Enum as constants public void onSomethingAction(int status) {
switch (status) { case Status.OK: // => int Log.d(TAG, "status: OK"); break; case Status.ERROR: // => int Log.d(TAG, "status: ERROR"); break; } }
Example - Enum as constants public void onSomethingAction(Status status) {
Log.d(TAG: "status: " + status.name()); }
Example - Enum as constants public void onSomethingAction(Status status) {
Log.d(TAG: "status: " + status.name()); } \ enum /
* type safe ! - "int enum pattern" is fragile
- Add/Remove a new item easliy * Prefixes of names are unnecessary - Because each enum types has its own namespace Enum as constants
Enum that has member constants/methods public enum Status { OK("Succeed
the process!"), ERROR("Error has occurred..."); private final String message; Status(String message) { this.message = message; } private String getMessage() { return message; } }
Enum that has member constants/methods public enum Status { OK("Succeed
the process!"), ERROR("Error has occurred..."); private final String message; Status(String message) { this.message = message; } private String getMessage() { return message; } }
Enum that has member constants/methods public enum Status { OK("Succeed
the process!"), ERROR("Error has occurred..."); private final String message; Status(String message) { this.message = message; } private String getMessage() { return message; } }
Example - Enum that has member constants/methods public void onSomethingAction(int
status) { switch (status) { case Status.OK: Log.d(TAG, "Succeed the process!"); break; case Status.ERROR: Log.d(TAG, "Error has occurred..."); break; } }
Example - Enum that has member constants/methods public void onSomethingAction(Status
status) { Log.d(TAG, status.getMessage()); }
Example - Enum that has member constants/methods public void onSomethingAction(Status
status) { Log.d(TAG, status.getMessage()); } \ enum /
Constant-specific method implementations public enum Status { OK("Succeed the process!")
{ @Override void log(String tag) { Log.d(tag, message); } }, ERROR("Error has occurred...") { @Override void log(String tag) { Log.e(tag, message); } }; // ... abstract void log(String tag); }
Constant-specific method implementations public enum Status { OK("Succeed the process!")
{ @Override void log(String tag) { Log.d(tag, message); } }, ERROR("Error has occurred...") { @Override void log(String tag) { Log.e(tag, message); } }; // ... abstract void log(String tag); }
Constant-specific method implementations public enum Status { OK("Succeed the process!")
{ @Override void log(String tag) { Log.d(tag, message); } }, ERROR("Error has occurred...") { @Override void log(String tag) { Log.e(tag, message); } }; // ... abstract void log(String tag); }
Constant-specific method implementations public enum Status { OK("Succeed the process!")
{ @Override void log(String tag) { Log.d(tag, message); } }, ERROR("Error has occurred...") { @Override void log(String tag) { Log.e(tag, message); } }; // ... abstract void log(String tag); }
* type safe !! * Implements comparable / serializable *
They are immutable / singleton Constants / Methods
Event handling with enum
Example - handling click event public void onClick(View v) {
swtich(v.getId()) { case R.id.button1: // do something... break; case R.id.button2: // do something... break; // ... } }
Example - handling click event
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ @Override public void handle(Context context) { /* ...*/ } }, BUTTON2(R.id.button2) { @Override public void handle(Context context) { /* ...*/ } }; // ... abstract public void handle(Context context); }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ @Override public void handle(Context context) { /* ...*/ } }, BUTTON2(R.id.button2) { @Override public void handle(Context context) { /* ...*/ } }; // ... abstract public void handle(Context context); }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ @Override public void handle(Context context) { /* ...*/ } }, BUTTON2(R.id.button2) { @Override public void handle(Context context) { /* ...*/ } }; // ... abstract public void handle(Context context); }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ /* ... */ }, BUTTON2(R.id.button2) { /* ... */ }; // ... public static ClickEventHandler valueOf(int resId) { for (ClickEventHandler handler : values()) { if (handler.getResId() == resId) { return handler; } } throw new IllegalArgumentException(); } }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ /* ... */ }, BUTTON2(R.id.button2) { /* ... */ }; // ... public static ClickEventHandler valueOf(int resId) { for (ClickEventHandler handler : values()) { if (handler.getResId() == resId) { return handler; } } throw new IllegalArgumentException(); } }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ /* ... */ }, BUTTON2(R.id.button2) { /* ... */ }; // ... public static ClickEventHandler valueOf(int resId) { for (ClickEventHandler handler : values()) { if (handler.getResId() == resId) { return handler; } } throw new IllegalArgumentException(); } }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ /* ... */ }, BUTTON2(R.id.button2) { /* ... */ }, UNKNOWN(-1) { @Override public void handle(Context context) {} }; // ... public static ClickEventHandler valueOf(int resId) { for (ClickEventHandler handler : values()) { if (handler.getResId() == resId) { return handler; } } return UNKNOWN; } }
Example - handling click event public enum ClickEventHandler { BUTTON1(R.id.button1)
{ /* ... */ }, BUTTON2(R.id.button2) { /* ... */ }, UNKNOWN(-1) { @Override public void handle(Context context) {} }; // NULL Object pattern // ... public static ClickEventHandler valueOf(int resId) { for (ClickEventHandler handler : values()) { if (handler.getResId() == resId) { return handler; } } return UNKNOWN; } }
Example - handling click event public void onClick(View v) {
ClickEventHandler.valueOf(v.getId()).handle(this); }
Example - handling click event public void onClick(View v) {
ClickEventHandler.valueOf(v.getId()).handle(this); }
* Delegates event handling from controller - We can avoid
fat controller !!!! * Improves testability - Because they are referentially transparent (?) * Other usecases - BLE (BluetoothGattCharacteristic), HTTP response, etc. Event handling with enum
Why don’t you use enum ?