❮

[Kotlin] 정렬

20190728

[Kotlin] 정렬

매우 혼란스러우니 주의.

출처

link 1

Collection 에서의 정렬

열기

1. sort()

주어진 콜렉션을 오름차순으로 정렬해준다. 기존 배열을 변경하는 메소드이기 때문에 Mutable 콜렉션에만 적용 가능.

val sortedValues = mutableListOf(1,2,7,6,5,6)
sortedValues.sort()
println(sortedValues)

내림차순 정렬을 하려면 sortDescending() 을 하거나 reverse() 메소드를 사용
기존 배열을 유지하고 싶다면 sorted() 사용

2. sortBy()

주어진 객체의 특정 속성을 기준으로 정렬한다. sort() 와 마찬가지 이유로 Mutable 콜렉션에만 적용 가능

val sortedValues = mutableListOf(1 to "a", 2 to "b", 7 to "c", 6 to "d", 5 to "c", 6 to "e")
sortedValues.sortBy { it.second }
println(sortedValues)

내림차순을 위해서는 sortByDescending 이나 reverse 메소드 사용
기존 배열을 유지하고 싶다면 sortedBy() 사용

3. sortWith()

고급 정렬을 위해서 인수로 Comparator를 전달할 수 있다.

val sortedValues = mutableListOf(1 to "a", 2 to "b", 7 to "c", 6 to "d", 5 to "c", 6 to "e")
sortedValues.sortWith(compareBy({it.second}, {it.first}))
println(sortedValues)

기존 배열 유지 : sortedWith

비교 (kotlin.comparsions)

열기

1. Comparator 만들기

여러 팩토리 메소드를 제공하고 있다.

naturalOrder<>()

가장 간단한 Comparator는 naturalOrder() 다. 별도의 매개변수가 필요없고 오름차순이 된다. 직접적으로 쓸 일을 많지 않을 것이다.

val ascComparator = naturalOrder<Long>()

compareBy<>()

여러 속성을 가진 객체를 위해서 compareBy 메소드를 사용할 수 있다.

val complexComparator = compareBy<Pair<Int, String?>>({it.first}, {it.second})

it.first를 기준으로 먼저 비교하고, 같으면 it.second을 기준으로 비교한다.

2. null 값 처리

nullsFirst 또는 nullsLast 메소드를 사용해서 null 값을 처음이나 마지막으로 오게 할 수 있다.

val sortedValues = mutableListOf(1 to "a", 2 to null, 7 to "c", 6 to "d", 5 to "c", 6 to "e")
sortedValues.sortWith(nullsLast(compareBy{it.second}))
println(sortedValues)

3. 순서를 반대로

Comparator 객체에 reverseOrder() 메소드를 사용한다.

4. 비교 규칙 확장

then 메소드를 사용해서 Comparator에 새로운 비교 규칙을 추가할 수 있다.
thenBy thenByDescending

val list = listOf("A", "aa", "b", "bb", "a")
val lengthThenCaseInsensitive = compareBy<String>{it.length}.then(String.CASE_INSENSITIVE_ORDER)

val sorted = list.sortedWith(lengthThenCaseInsensitive)

println(sorted) // [A, a, b, aa, bb]

Categories

flutter ( 82 ) dart ( 34 ) android ( 32 ) kotlin ( 11 ) plugin ( 8 ) provider ( 8 ) vim ( 7 ) bloc ( 6 ) iOS ( 6 ) state management ( 6 ) 플러터 ( 6 ) PS ( 5 ) algorithm ( 5 ) architecture ( 5 ) async ( 5 ) getx ( 5 ) java ( 5 ) API ( 4 ) BOJ ( 4 ) class ( 4 ) daily ( 4 ) git ( 4 ) golang ( 4 ) memo ( 4 ) riverpod ( 4 ) state ( 4 ) stream ( 4 ) test ( 4 ) web ( 4 ) widget ( 4 ) windows ( 4 ) HTTP ( 3 ) androidX ( 3 ) app state ( 3 ) context ( 3 ) crash ( 3 ) db ( 3 ) editor ( 3 ) error ( 3 ) extension ( 3 ) github ( 3 ) hive ( 3 ) ide ( 3 ) package ( 3 ) pubspec ( 3 ) python ( 3 ) syntax ( 3 ) vscode ( 3 ) app icon ( 2 ) await ( 2 ) chocolatey ( 2 ) consumer ( 2 ) cp949 ( 2 ) deployment ( 2 ) dev ( 2 ) flavor ( 2 ) gesture ( 2 ) globalkey ( 2 ) go ( 2 ) google ( 2 ) hack ( 2 ) js ( 2 ) json ( 2 ) key ( 2 ) keystore ( 2 ) list ( 2 ) listview ( 2 ) lock ( 2 ) mac ( 2 ) map ( 2 ) navigation ( 2 ) nosql ( 2 ) project ( 2 ) pub ( 2 ) recyclerview ( 2 ) rxdart ( 2 ) sdk ( 2 ) selector ( 2 ) setting ( 2 ) size ( 2 ) soc ( 2 ) synchronized ( 2 ) tdd ( 2 ) tip ( 2 ) version ( 2 ) viewmodel ( 2 ) vundle ( 2 ) webview ( 2 ) xcode ( 2 ) yaml ( 2 ) 책 ( 2 ) 플러터 단점 ( 2 ) 16.0 ( 1 ) 2.0 ( 1 ) 2023 ( 1 ) AATP2 ( 1 ) ChangeNotifierProvider ( 1 ) Example ( 1 ) Guava ( 1 ) ImageReader ( 1 ) Mo's algorithm ( 1 ) OAuth2 ( 1 ) OpenGL ( 1 ) Oreo ( 1 ) ProgressBar ( 1 ) REST API ( 1 ) Trie ( 1 ) activity ( 1 ) adaptive ( 1 ) android P ( 1 ) android context ( 1 ) android11 ( 1 ) apktool2 ( 1 ) app exit ( 1 ) append ( 1 ) appicon ( 1 ) arkit ( 1 ) array ( 1 ) asciidoc ( 1 ) async * ( 1 ) async* ( 1 ) audio ( 1 ) authorization ( 1 ) await for ( 1 ) behaviorsubject ( 1 ) beta ( 1 ) binary ( 1 ) binarysearch ( 1 ) blender ( 1 ) book ( 1 ) bottomsheet ( 1 ) break ( 1 ) broadcast ( 1 ) browser ( 1 ) bubbles ( 1 ) bug ( 1 ) build ( 1 ) buildcontext ( 1 ) buildnumber ( 1 ) bundle ( 1 ) button ( 1 ) bytecode ( 1 ) cache ( 1 ) camera2 ( 1 ) cameramanager ( 1 ) cd ( 1 ) chrome ( 1 ) ci ( 1 ) circle ( 1 ) clean ( 1 ) clean architecture ( 1 ) cli ( 1 ) clip ( 1 ) clipboard ( 1 ) cloud ide ( 1 ) cmdlet ( 1 ) code ( 1 ) coding test ( 1 ) command ( 1 ) comparator ( 1 ) complexity ( 1 ) concurrency ( 1 ) conditional ( 1 ) const ( 1 ) constraint ( 1 ) constraintlayout ( 1 ) controlc ( 1 ) controlv ( 1 ) converter ( 1 ) copy ( 1 ) copy project ( 1 ) coupling ( 1 ) coverage ( 1 ) cp ( 1 ) css ( 1 ) cupertino ( 1 ) cursor ( 1 ) cv ( 1 ) data class ( 1 ) data structure ( 1 ) dataBinding ( 1 ) database ( 1 ) debounce ( 1 ) decompile ( 1 ) delegate ( 1 ) deno ( 1 ) design pattern ( 1 ) development ( 1 ) device ( 1 ) di ( 1 ) dialog ( 1 ) dio ( 1 ) drawable ( 1 ) drug ( 1 ) emmet ( 1 ) encoding ( 1 ) english ( 1 ) entries ( 1 ) environment ( 1 ) equality ( 1 ) equatable ( 1 ) euc-kr ( 1 ) euckr ( 1 ) exit ( 1 ) expand ( 1 ) expanded ( 1 ) export ( 1 ) extension method ( 1 ) facade ( 1 ) fake ( 1 ) field ( 1 ) figma ( 1 ) final ( 1 ) fixed ( 1 ) flutter pub ( 1 ) flutter web ( 1 ) flutter_inappwebview ( 1 ) flutter_test ( 1 ) flutterflow ( 1 ) fold ( 1 ) fonts ( 1 ) form ( 1 ) frame ( 1 ) future ( 1 ) gestureDetector ( 1 ) gestureRecognizer ( 1 ) gesturearena ( 1 ) get-command ( 1 ) get_cli ( 1 ) getbuilder ( 1 ) getx단점 ( 1 ) gitignore ( 1 ) glut ( 1 ) google fonts ( 1 ) gopath ( 1 ) goto ( 1 ) gradient ( 1 ) graphics ( 1 ) gvim ( 1 ) hackaton ( 1 ) hash ( 1 ) hashmap ( 1 ) hot reload ( 1 ) how to ( 1 ) html ( 1 ) i18n ( 1 ) icon ( 1 ) id ( 1 ) impeller ( 1 ) implementation ( 1 ) import ( 1 ) indicator ( 1 ) inkwell ( 1 ) interrupt ( 1 ) intl ( 1 ) introduction ( 1 ) io ( 1 ) isar ( 1 ) iterable ( 1 ) iteration ( 1 ) javascript ( 1 ) julia ( 1 ) juno ( 1 ) jupyter ( 1 ) kakaomap ( 1 ) keytool ( 1 ) korean ( 1 ) kotlin syntax ( 1 ) l10n ( 1 ) lambda ( 1 ) language ( 1 ) layer ( 1 ) layout ( 1 ) lineageOS ( 1 ) localkey ( 1 ) localtoglobal ( 1 ) long list ( 1 ) ls ( 1 ) mac osx ( 1 ) markdown ( 1 ) markup ( 1 ) material ( 1 ) method ( 1 ) microtask ( 1 ) migrate ( 1 ) mintlify ( 1 ) mock ( 1 ) module ( 1 ) monitor ( 1 ) moor ( 1 ) mouse ( 1 ) mouseregion ( 1 ) multiplatform ( 1 ) multiset ( 1 ) multithread ( 1 ) mutable ( 1 ) mvvm ( 1 ) new ( 1 ) node ( 1 ) nodejs ( 1 ) nosuchmethod ( 1 ) null-safety ( 1 ) numberformat ( 1 ) nvim ( 1 ) object ( 1 ) objectbox ( 1 ) objectkey ( 1 ) obx ( 1 ) online ide ( 1 ) operator ( 1 ) orientation ( 1 ) parabeac ( 1 ) parse ( 1 ) paste ( 1 ) path ( 1 ) pattern ( 1 ) pitfall ( 1 ) play store ( 1 ) pod ( 1 ) podfile ( 1 ) pointer ( 1 ) pointers ( 1 ) powershell ( 1 ) private ( 1 ) programming ( 1 ) pull to refresh ( 1 ) puzzle ( 1 ) pycharm ( 1 ) realitykit ( 1 ) recursion ( 1 ) reduce ( 1 ) reference ( 1 ) regex ( 1 ) regular expression ( 1 ) release note ( 1 ) renderbox ( 1 ) renderobject ( 1 ) repl ( 1 ) repository ( 1 ) response ( 1 ) rm ( 1 ) rotue ( 1 ) round ( 1 ) run ( 1 ) scope ( 1 ) scroll ( 1 ) search ( 1 ) server ( 1 ) serverless ( 1 ) service ( 1 ) sharp ( 1 ) singlerepo ( 1 ) singleton ( 1 ) sketch ( 1 ) sliver ( 1 ) sliverlist ( 1 ) snippets ( 1 ) sogae ( 1 ) sorting ( 1 ) source ( 1 ) sparse ( 1 ) sparse array ( 1 ) spec ( 1 ) split ( 1 ) sqflite ( 1 ) sqlite ( 1 ) sqrt decomposition ( 1 ) stateful ( 1 ) statefulwidget ( 1 ) step ( 1 ) stepper ( 1 ) string ( 1 ) stringbuffer ( 1 ) stringbuilder ( 1 ) studio ( 1 ) study ( 1 ) sub-directory ( 1 ) svn ( 1 ) swiftui ( 1 ) swipe to refresh ( 1 ) system_alert_window ( 1 ) system_cache ( 1 ) systemnavigator ( 1 ) tail recursion ( 1 ) tailrec ( 1 ) tap test ( 1 ) text ( 1 ) texteditingcontroller ( 1 ) textfield ( 1 ) texttheme ( 1 ) themedata ( 1 ) then ( 1 ) thread ( 1 ) throttle ( 1 ) time ( 1 ) tool ( 1 ) tools ( 1 ) tooltip ( 1 ) ts ( 1 ) tutorial ( 1 ) typescript ( 1 ) ui ( 1 ) unittest ( 1 ) update ( 1 ) usb ( 1 ) utf8 ( 1 ) ux ( 1 ) valuekey ( 1 ) variable ( 1 ) vector ( 1 ) versioncode ( 1 ) very_good ( 1 ) view ( 1 ) vim plugin ( 1 ) vimrc ( 1 ) virtualenv ( 1 ) wasm ( 1 ) web app ( 1 ) webview_flutter ( 1 ) while ( 1 ) widget tree ( 1 ) window ( 1 ) wsl ( 1 ) yield ( 1 ) 강의 ( 1 ) 개발 ( 1 ) 개발 공부 ( 1 ) 공부법 ( 1 ) 그래픽스 ( 1 ) 꼬리재귀 ( 1 ) 꿀팁 ( 1 ) 데노 ( 1 ) 두줄 ( 1 ) 디노 ( 1 ) 번역 ( 1 ) 블록 ( 1 ) 상태관리 ( 1 ) 실험 ( 1 ) 안드로이드 ( 1 ) 안드로이드프로젝트 ( 1 ) 안드로이드프로젝트복사 ( 1 ) 어이없는 ( 1 ) 조건부 임포트 ( 1 ) 주절주절분노조절실패의식으흐름 ( 1 ) 패키지 ( 1 ) 프로젝트복사 ( 1 ) 플러그인 ( 1 )

시리즈

❮

[Kotlin] 정렬

algorithm

comparator

kotlin

sorting

[Kotlin] 정렬

출처

Collection 에서의 정렬

1. sort()

2. sortBy()

3. sortWith()

비교 (kotlin.comparsions)

1. Comparator 만들기

naturalOrder<>()

compareBy<>()

2. null 값 처리

nullsFirst 또는 nullsLast 메소드를 사용해서 null 값을 처음이나 마지막으로 오게 할 수 있다.

3. 순서를 반대로

4. 비교 규칙 확장

.

piano (press key Q)

Categories