[B! null] decoy2004ã®ãƒ–ãƒƒã‚¯ãƒžãƒ¼ã‚¯

decoy2004 id:decoy2004

nullã«é–¢ã™ã‚‹decoy2004ã®ãƒ–ãƒƒã‚¯ãƒžãƒ¼ã‚¯ (8)

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è„±ãƒ“ã‚®ãƒŠãƒ¼ï¼Androidã®nullãªè©± - ã‚¯ãƒƒã‚¯ãƒ‘ãƒƒãƒ‰é–‹ç™ºè€…ãƒ–ãƒã‚°
æ–°è¦åºƒå‘Šé–‹ç™ºéƒ¨ã®æ¾æœ¬ã§ã™ã€‚ ã‚¯ãƒƒã‚¯ãƒ‘ãƒƒãƒ‰iOS/Androidã‚¢ãƒ—ãƒªã®åºƒå‘Šã®é–‹ç™ºã«æºã‚ã£ã¦ã„ã¾ã™ã€‚ Androidã‚¢ãƒ—ãƒªé–‹ç™ºã®éš›ã€çš†ã•ã‚“ã¯nullã‚’ã©ã®ã‚ˆã†ã«æ‰±ã£ã¦ã„ã¾ã™ã‹ï¼Ÿã¾ãŸã€nullãƒã‚§ãƒƒã‚¯ã‚’è¡Œã†ã®ã§ã‚ã‚Œã°ã€ã©ã®ã‚ˆã†ãªåŸºæº–ã§è¡Œã£ã¦ã„ã¾ã™ã‹ï¼Ÿç§è‡ªèº«ã¾ã ã¾ã Androidé–‹ç™ºæ´ãŒæµ…ã„ãŸã‚ã€ç‰¹ã«ä½•ã‹åŸºæº–ãŒã‚ã‚‹è¨³ã§ã‚‚ãªãè‡³ã‚‹æ‰€ã§if (foo != null)ã¨ã„ã£ãŸnullãƒã‚§ãƒƒã‚¯ã‚’è¡ŒãŠã†ã¨ã—ã¦ã„ã¾ã—ãŸã€‚ ã“ã‚Œã«å¯¾ã—ã€å…ˆæ—¥ã®ç¤¾å†…ã‚³ãƒ¼ãƒ‰ãƒ¬ãƒ“ãƒ¥ãƒ¼ã§ã¨ã¦ã‚‚ãŸã‚ã«ãªã‚‹ã‚¢ãƒ‰ãƒã‚¤ã‚¹ã‚’ã‚‚ã‚‰ã„ã¾ã—ãŸã€‚ç§ã®ã‚ˆã†ãªAndroidåˆå¿ƒè€…ã«ã¨ã£ã¦nullã«å¯¾ã™ã‚‹è€ƒãˆæ–¹ã®åŸºç¤Žã‚’ä½œã£ã¦ãã‚Œã‚‹ãƒ¬ãƒ“ãƒ¥ãƒ¼ã ã£ãŸã®ã§ã€æœ¬ç¨¿ã§å…±æœ‰ã—ãŸã„ã¨æ€ã„ã¾ã™ã€‚ ã¾ãŸã€Androidã‚„Javaé–‹ç™ºã«æ…£ã‚ŒãŸæ–¹ã«ã¨ã£ã¦ã¯ã€Œä»Šæ›´ãã‚“ãªè©±ã‹ã€ã¨ã„ã£ãŸå†…å®¹ã‹ã¨æ€ã„ã¾ã™ãŒã€ã‚¯ãƒƒã‚¯ãƒ‘ãƒƒãƒ‰ã§ã®ãƒ¬ãƒ“ãƒ¥ãƒ¼ã®ä¸€ä¾‹ã¨ã—ã¦ã”è¦§ã„ãŸã ã‘ã‚Œã°å¹¸ã„ã§ã™ã€‚ ã‚„ã‚ŠãŒã¡ãªnul
decoy2004 2015/02/24
java

programming

null
ãƒªãƒ³ã‚¯
nullä½¿ã£ãŸã‚‰è² ã‘ç¦å²¡ç‰ˆ
8. Optionalã‚’ç”¨æ„ã™ã‚‹ â— å€¤ãŒã‚ã‚‹ Optional.of(str) â€“ nullã‚’æ¸¡ã™ã¨ã¬ã‚‹ã½ â— å€¤ãŒãªã„ Optional.empty() â— å€¤ãŒã‚ã‚‹ã‹ã©ã†ã‹ã‚ã‹ã‚‰ãªã„ Optional.ofNullable(str) 9. å€¤ã®å–å¾— â— get() â€“ å€¤ãŒãªã„ã¨ãNoSuchElementException â— orElse(defaultValue) â€“ å€¤ãŒãªã„ã¨ãdefaultValue â— orElseGet(() -> defaultValue) â€“ å€¤ãŒãªã„ã¨ãã«defaultValueå–å¾—å‡¦ç† â— orElseThrow(() -> new Exception()) â€“ å€¤ãŒãªã„ã¨ãä¾‹å¤–ã‚’ç”Ÿæˆã—ã¦æŠ•ã’ã‚‹
decoy2004 2014/11/10
null

programming

java

slide

java8
ãƒªãƒ³ã‚¯
Eclipse ã§ Null è§£æžã—ã¤ã¤ guava ã‚’ä½¿ã„ãŸã„ - Qiita
@yuichielectric ã•ã‚“ãŒã“ã¡ã‚‰ã§æ›¸ã‹ã‚Œã¦ã„ã¾ã™ãŒ, æœ€è¿‘ã® Eclipse ã§ã¯é™çš„ãª Null ãƒã‚§ãƒƒã‚¯ãŒå‡ºæ¥ã‚‹ã¿ãŸã„ã§ã™ã€‚ã“ã‚Œã¯ç´ æ™´ã‚‰ã—ã„ã¨æ€ã£ãŸã®ã§æ—©é€Ÿè©¦ã—ã¦ã¿ãŸã®ã§ã™ãŒ, guava ã¨çµ„ã¿åˆã‚ã›ã¦ä½¿ãŠã†ã¨ã™ã‚‹ã¨å°‘ã€…å•é¡ŒãŒç™ºç”Ÿã™ã‚‹ã“ã¨ã«æ°—ä»˜ãã¾ã™â€¦â€¦ã€‚ ã‚»ãƒƒãƒˆã‚¢ãƒƒãƒ— ã¾ãš @yuichielectric ã•ã‚“ã®è¨˜äº‹ã‚’å‚è€ƒã« Eclipse (Juno) ã®ã‚»ãƒƒãƒˆã‚¢ãƒƒãƒ—ã‚’è¡Œã„ã¾ã™ã€‚æ¬¡ã«, javax.annotation.Nullable ãŒå¿…è¦ãªã®ã§ JSR305 ã‚’ä¾å˜é–¢ä¿‚ã«è¿½åŠ ã—ã¾ã™ã€‚ // build.gradle dependencies { compile com.google.code.findbugs:jsr305:2.0.1 compile com.google.guava:guava:14.0.1 } ã“ã‚Œã§æº–å‚™ã¯å®Œäº†ã§ã™ã€‚ãã¡ã‚“ã¨é™çš„è§£æžãŒåŠ¹ã„ã¦ã„
decoy2004 2014/08/17
eclipse

guava

null

jsr305

java
ãƒªãƒ³ã‚¯
ãƒ¡ã‚½ãƒƒãƒ‰å†…ã§ãƒ‘ãƒ©ãƒ¡ãƒ¼ã‚¿ã®å€¤ãƒã‚§ãƒƒã‚¯ã‚’è¡Œã† - Qiita
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decoy2004 2014/08/17
ã€ŽJDK7ã‹ã‚‰java.util.Objectsã¨ã„ã†ã‚¯ãƒ©ã‚¹ã§requireNonNullã€ã€Žã‚¨ãƒ©ãƒ¼ãƒ¡ãƒƒã‚»ãƒ¼ã‚¸ã®ç”Ÿæˆã«printfã£ã½ã„ãƒ•ã‚©ãƒ¼ãƒžãƒƒã‚¿ã‚’ä½¿ãˆã‚‹ç‚¹ã§Guavaã®æ–¹ãŒå„ªã‚Œã¦ã„ã‚‹ã€

null

java
ãƒªãƒ³ã‚¯
Eclipse Junoã§nullè§£æžã‚’è¡Œã† - Qiita
Eclipse Junoã§nullè§£æžã‚’è¡Œã† Eclipse Juno(4.2)ã‹ã‚‰ã€@NullableãŒä»˜ã„ãŸãƒ‘ãƒ©ãƒ¡ãƒ¼ã‚¿ã‚’ã€ãã®ãƒ¡ã‚½ãƒƒãƒ‰å†…ã§Nullãƒã‚§ãƒƒã‚¯ã—ã¦ã„ãªã„å ´åˆã¯warningã‚„errorã«ã™ã‚‹ã“ã¨ãŒå‡ºæ¥ã‚‹ã‚ˆã†ã«ãªã‚Šã¾ã™ã€‚ @Nullable Nullableã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³ãŒã¤ã„ã¦ã„ã‚‹ãƒ‘ãƒ©ãƒ¡ãƒ¼ã‚¿ã¯ã€ãã®ãƒ‘ãƒ©ãƒ¡ãƒ¼ã‚¿ã«ã¯NullãŒæ¸¡ã•ã‚Œã‚‹ã“ã¨ã‚‚è¨±å®¹ã™ã‚‹ã¨ã„ã†æ„å‘³ã«ãªã‚Šã¾ã™ã€‚ ãªã®ã§ã€ãƒ¡ã‚½ãƒƒãƒ‰å†…ã§å€¤ã®Nullãƒã‚§ãƒƒã‚¯ã‚’è¡Œã†å¿…è¦ãŒã‚ã‚Šã¾ã™ã€‚ ä¾‹ãˆã°ã€ä»¥ä¸‹ã®ã‚ˆã†ãªã‚³ãƒ¼ãƒ‰ã‚’æ›¸ã„ãŸã¨ã—ã¾ã™ã€‚ import static org.junit.Assert.assertEquals; import javax.annotation.Nullable; import org.junit.Test; public class NullableTest { @Test public void test
decoy2004 2014/08/17
ã€ŽPreferencesã®ã€ŒJava > Compiler > Errors/Warningsã€ã®ä¸€ç•ªä¸‹ã«ã€ŒNull analysisã€ã¨ã„ã†é …ç›®ãŒã‚ã‚Šã¾ã™ã€‚ã€

java

Eclipse

null

jsr305

annotation

tips
ãƒªãƒ³ã‚¯
FindBugs ã® @NonNull @CheckForNull ã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³ - ã‚ã‚‹ãƒ—ãƒã‚°ãƒ©ãƒžã®æ—¥è¨˜
FindBugs ã® @NonNull ã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³ã§å¼•æ•°ã‚„æˆ»ã‚Šå€¤ãŒ null ã§ãªã„ã“ã¨ã‚’æ˜Žç¤ºã™ã‚‹ã¨ã€å¯èªæ€§ã‚‚ã‚ˆããªã‚‹ã—ã€é–“é•ã£ã¦ null ã®å¼•æ•°ã‚’æŒ‡å®šã—ãŸã‚Šã€null ã‚’è¿”ã™ã‚³ãƒ¼ãƒ‰ã‚’æ›¸ãã¨ã€FindBugs ã®æŒ‡æ‘˜ãŒå…¥ã‚‹ã®ã§ã€ä¸è¦ãª null ãƒã‚§ãƒƒã‚¯ã®å†—é•·ãªã‚³ãƒ¼ãƒ‰ãŒæ¸›å°‘ã™ã‚‹ã€‚ import edu.umd.cs.findbugs.annotations.NonNull; .. @NonNull public String get(@NonNull String key) { .. return .. } .. é€†ã«ã€ã©ã†ã—ã¦ã‚‚ null ã®å¼•æ•°æŒ‡å®šã‚„ null ã®æˆ»ã‚Šå€¤ãŒç™ºç”Ÿã™ã‚‹å ´åˆã¯ ï¼ CheckForNull ã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³ã‚’ä»˜ã‘ã¦ null ãƒã‚§ãƒƒã‚¯ã‚³ãƒ¼ãƒ‰ã‚’æ›¸ãã‚ˆã†ã«æ˜Žç¤ºã™ã‚‹ã“ã¨ãŒã§ãã‚‹ã€‚ã“ã¡ã‚‰ã¯ null ãƒã‚§ãƒƒã‚¯ãŒãªã„ã¨ FindBugs ãŒæŒ‡æ‘˜ã—ã¦ãã‚Œã‚‹ã€‚ impor
decoy2004 2014/08/08
ã€ŽFindBugs ã® @NonNull ã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³ã§å¼•æ•°ã‚„æˆ»ã‚Šå€¤ãŒ null ã§ãªã„ã“ã¨ã‚’æ˜Žç¤ºã™ã‚‹ã¨ã€é–“é•ã£ã¦ null ã®å¼•æ•°ã‚’æŒ‡å®šã—ãŸã‚Šã€null ã‚’è¿”ã™ã‚³ãƒ¼ãƒ‰ã‚’æ›¸ãã¨ã€FindBugs ã®æŒ‡æ‘˜ãŒå…¥ã‚‹ã€

java

FingBugs

null

annotation
ãƒªãƒ³ã‚¯
The Checker Framework Manual: Custom pluggable types for Java
The Checker Framework Manual: Custom pluggable types for Javahttps://checkerframework.orgVersion 3.48.2 (1 Nov 2024) For the impatient: Sectionâ€„â€1.3 describes how to install and use pluggable type-checkers. This manual is also available in PDF. Contents Chapterâ€„â€1â€ƒIntroduction 1.1â€ƒHow to read this manual 1.2â€ƒHow it works: Pluggable types 1.3â€ƒInstallation 1.4â€ƒExample use: detecting a null pointer b
decoy2004 2014/08/07
ã€ŽLock Checker for concurrency and lock errors (see Chapter 5)ã€

java

null

java8

framework
ãƒªãƒ³ã‚¯
ã€Œnullã€ã‚’ãƒ•ãƒ©ã‚°ã¨ã—ã¦ä½¿ã†ã®ã¯ã€ã‚„ã‚ãŸæ–¹ãŒã„ã„ - åœ°å¹³ç·šã«è¡Œã
null ã‚’ãƒ•ãƒ©ã‚°ã¨ã—ã¦ä½¿ã†ã®ã¯ã€ã‚„ã‚ãŸæ–¹ãŒã„ã„ã¨æ€ã„ã¾ã™ã€‚ null ã¯ã€ãŸã å¤‰æ•°ãŒåˆæœŸåŒ–ã•ã‚Œã¦ã„ãªã„ã“ã¨ã‚’è¡¨ã—ã¦ã„ã‚‹ã ã‘ã§ã™ã€‚ ã“ã®æ„å‘³ä»¥å¤–ã§ã€null ã‚’ä½¿ã‚ãªã„æ–¹ãŒã„ã„ã¨æ€ã„ã¾ã™ã€‚ null ã‚’ãƒ•ãƒ©ã‚°ã¨ã—ã¦ä½¿ã† ã€Œnull ã‚’ãƒ•ãƒ©ã‚°ã¨ã—ã¦ä½¿ã†ã€ã¨ã„ã†ã®ã¯ã€ã€Œnull ãªã‚‰ xxxxã€ã¨ã„ã†ã‚ˆã†ã«ã€null ãŒä½•ã‚‰ã‹ã®æ„å‘³ã‚’æŒã£ã¦ä½¿ã‚ã‚Œã¦ã„ã‚‹ã“ã¨ã‚’æŒ‡ã—ã¾ã™ã€‚ ä¾‹ãˆã°ã€ä¸‹è¨˜ã®ã‚³ãƒ¼ãƒ‰ã§ã¯ã€Œnull ã¯ã‚²ã‚¹ãƒˆãƒ¦ãƒ¼ã‚¶ã‚’æŒ‡ã™ãƒ•ãƒ©ã‚°ã€ã¨ã—ã¦ä½¿ã‚ã‚Œã¦ã„ã¾ã™ã€‚ /** * ãƒ¦ãƒ¼ã‚¶ç”¨ã®ãƒ˜ãƒƒãƒ€ã‚’ä½œã‚‹å‡¦ç† */ public String createHeader(User user){ (â€¦ä¸ç•¥â€¦) String name; if(user != null){ name = user.getName(); }else{ name = "Guest"; // null ãªã‚‰ã‚²ã‚¹ãƒˆãƒ¦ãƒ¼ã‚¶ } å•é¡Œç‚¹ ã“ã‚Œã®
decoy2004 2014/08/01
ã€Žä¾‹ãˆã°ã€ä»¥ä¸‹ã®ã‚³ãƒ¼ãƒ‰ã‚’è¦‹ãŸã¨ãã«null ã®æ„å‘³ã‚’ã™ãã«ç†è§£ã§ãã‚‹ã§ã—ã‚‡ã†ã‹ String header = createHeader(null);ã€

String

java

programming

null
ãƒªãƒ³ã‚¯
1