[B! null] somemoã®ãƒ–ãƒƒã‚¯ãƒžãƒ¼ã‚¯

somemo id:somemo

nullã«é–¢ã™ã‚‹somemoã®ãƒ–ãƒƒã‚¯ãƒžãƒ¼ã‚¯ (4)

${{author_name}}$

{{{comment_expanded}}}

{{label}}

{{#is_bookmark}}ãƒªã‚¹ãƒˆ{{/is_bookmark}}{{^is_bookmark}}ãƒªãƒ³ã‚¯{{/is_bookmark}}

${{author_name}}$
{{author_name}}{{created}}
{{ #comment }}{{ comment }}{{ /comment }}
- {{ label }}

${{author_name}}$

{{{comment_expanded}}}

{{label}}

{{#is_bookmark}}ãƒªã‚¹ãƒˆ{{/is_bookmark}}{{^is_bookmark}}ãƒªãƒ³ã‚¯{{/is_bookmark}}

Nullableã¨Optionã®é•ã„ - ãã‚‹ãã‚‹ï½ž
ã“ã®ã‚¨ãƒ³ãƒˆãƒªã®æœ€æ–°ç‰ˆã¯Githubã«ã‚ã‚Šã¾ã™ã€‚ Optionãã®ã‚‚ã®ã«ã¤ã„ã¦ã®ã‚¨ãƒ³ãƒˆãƒªã¯æ›¸ãå¿…è¦ãªã„(ä¸–ã®ä¸ã«æœ‰ç”¨ãªãƒ‰ã‚ãƒ¥ãƒ¡ãƒ³ãƒˆãŒå±±ã»ã©ã‚ã‚‹ã‹ã‚‰)ã‹ãªã€ ã¨æ€ã£ã¦ã„ãŸã®ã§ã™ãŒã€Nullableã¨ã®é•ã„ã«ã¤ã„ã¦ã¯ãã‚Œãªã‚Šã«éœ€è¦ãŒã‚ã‚Šãã†ãªã®ã§æ›¸ã„ã¦ãŠãã¾ã™ã€‚ ã¡ãªã¿ã«ã€å€‹äººçš„ãªå—œå¥½ã«ã‚ˆã‚ŠOptionã‚’æŒã¡ä¸Šã’ã€Nullableã‚’ä¸‹ã«æ‰±ã†æ„Ÿã˜ã«ãªã£ã¦ã„ã¾ã™ãŒã€Nullableã‚‚(ä»•æ–¹ãªã)ä½¿ã†ã“ã¨ã¯ã‚ã‚Šã¾ã™ã€‚ ç‰¹åˆ¥ãªç†ç”±ãŒãªã‘ã‚Œã°Nullableä½¿ã‚ãšã«Optionã‚’ä½¿ã†ã€ã¨ã„ã†ã“ã¨ã§ã‚‚ã‚ã‚Šã¾ã™ãŒã€ãã“ã¯ä¸€ã¤ã‚ˆã‚ã—ããŠé¡˜ã„ã—ã¾ã™ã€‚ Nullableã¨ã¯ C#ã§ã¯nullã¯å‚ç…§åž‹ã§ã—ã‹ä½¿ãˆã¾ã›ã‚“ã§ã—ãŸã€‚ Nullableã¯ã€ã“ã®åˆ¶é™ãŒãªã„(ã‚ˆã†ã«è¦‹ãˆã‚‹ã‚ˆã†ç‰¹åˆ¥æ‰±ã„ã•ã‚Œã¦ã„ã‚‹)å”¯ä¸€ã®å€¤åž‹ã§ã™ã€‚ ã‚¸ã‚§ãƒãƒªãƒƒã‚¯åž‹ã«ãªã£ã¦ãŠã‚Šã€ä»»æ„ã®å€¤åž‹ã‚’æ‰±ã†ã“ã¨ãŒå‡ºæ¥ã¾ã™ã€‚ // Nullable<int>ã¯int?
somemo 2013/06/11
c#

null
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®
somemo 2013/04/15
æœŸå¾…å€¤ãŒé…åˆ—ãªã®ã«nullã‚’ãªãœã‹ä½¿ã†ã¨ã‹ã‚ã‚‹ã‚ã‚‹â€¦

null

programming
ãƒªãƒ³ã‚¯
Maybeã«é™ã‚‰ãšJavaã§ç›´å’Œåž‹ã‚’å®Ÿç¾ã§ãã‚‹ã‹ - è²³ä½°ä¼æ‹¾é™¸å¤œæ—¥è¨˜
Javaã§Maybeã‚’èª¬æ˜Žã—ãŸä»¥ä¸‹ã®è¨˜äº‹ã«ã¤ã„ã¦, id:tozimaã•ã‚“ã¨æŸæ‰€*1ã§ã‚„ã‚Šã¨ã‚Šã—ã¦ã„ãŸã‚‰, æœ‰ç›Šãªè©±ãŒå‡ºã¦ããŸã®ã§ã¯ãªã„ã‹, ã¨ã„ã†ã“ã¨ã«ãªã£ãŸã®ã§, ç´¹ä»‹. åŸºæœ¬çš„ã«ã‚„ã‚Šã¨ã‚Šã‚’ãã®ã¾ã¾*2æŠœç²‹ã—ãŸã‚‚ã®ã«, é©å®œè£œè¶³ã‚’åŠ ãˆã¦ã„ãã¾ã™. ç™ºç«¯ 2012-06-29 04:29id:tozima ã“ã‚“ãªè¨˜äº‹ãŒã‚ã£ãŸã€‚ Java ã®èªžå½™ã§ Maybe ã‚’èª¬æ˜Žã—ã¦ã¿ã‚‹ - ãã‚‹ãã‚‹ï½ž ç›´å’Œåž‹ã®ã‚¨ãƒ³ã‚³ãƒ¼ãƒ‡ã‚£ãƒ³ã‚°ã§ã‚ã‚‹ã€ ã§Maybeãƒ¢ãƒŠãƒ‰ã‚’èª¬æ˜Žã—ã¦ã„ã‚‹ã€ã¾ã£ã¨ã†ãªè¨˜äº‹ã§ã™ã€‚æ°—ã«ãªã£ãŸã®ã¯ã€ä¸Šã®ã‚¨ãƒ³ã‚³ãƒ¼ãƒ‡ã‚£ãƒ³ã‚°ã‚’ Java ã®ä¸Šã§ã‚„ã£ã¦ã€ãªã«ã‹å¤‰ãªã“ã¨ãŒèµ·ããªã„ã®ã‹ã¨ã„ã†ã“ã¨ã€‚ä¾‹ãˆã°è¨˜äº‹ä¸ã§ã¯ã€ *3 ã¿ãŸã„ãªã“ã¨ãŒã€Javaã§ã¯ç¦æ¢ã§ããªã„ã€ã£ã¦ã“ã¨ã«ã¤ã„ã¦è§¦ã‚Œã¦ã„ã¾ã™ã€‚ã“ã®ä»–ã«ã¯å¤‰ãªã“ã¨ã¯ãŠããªã„ã‚“ã§ã—ã‚‡ã†ã‹ï¼Ÿ åƒ•ã«ã¯å…¨ç„¶Javaçš„ãªè¨€èªžã¸ã®ç›´æ„ŸãŒãªã„ã®ã§æ•™ãˆã¦ãã ã•ã„ï¼ï¼ï¼ ã€Œ.
somemo 2012/08/24
maybe

null

Java
ãƒªãƒ³ã‚¯
Java ã®èªžå½™ã§ Maybe ã‚’èª¬æ˜Žã—ã¦ã¿ã‚‹ - ãã‚‹ãã‚‹ï½ž
java-jaã§ä¾‹å¤–å‡¦ç†ã®è©±ã‚’ã—ã¦ãã¾ã—ãŸ - è¥¿å°¾æ³°å’Œã®ã¯ã¦ãªãƒ€ã‚¤ã‚¢ãƒªãƒ¼ ã‚’èªã‚“ã§ã€‚ Maybe ã¯å€¤ãŒã‚ã‚‹ã‹ãªã„ã‹ã‚’åž‹ã§è¡¨ã™ã“ã¨ãŒã§ãã¾ã™ï¼ãã†ã€ç›´å’Œåž‹ãªã‚“ã§ã™ï¼ã¨ã‹è¨€ã‚ã‚Œã¦ã‚‚ã‚¤ãƒŸãƒ•ã ã¨æ€ã†ã®ã§ã™(ãƒªãƒ³ã‚¯å…ˆã®ã‚¨ãƒ³ãƒˆãƒªãŒãã†èª¬æ˜Žã—ã¦ã‚‹ã‚ã‘ã§ã¯ãªã„ã§ã™ãŒ)ã€‚ Java ã®èªžå½™ã§ Maybe ã®èª¬æ˜Žã‚’ã§ããŸã‚‰å¬‰ã—ã„äººã‚‚ã„ã‚‹ã‚“ã˜ã‚ƒãªã„ã‹ãªãã€ã¨ã‹ãªã‚“ã¨ã‹ã€‚ ãŸã ã—ã€æ›¸ã„ã¦ãŸã‚‰çµæ§‹é•·ããªã‚Šã¾ã—ãŸã€‚æ™‚é–“ãŒã‚ã‚‹äººã¯ã©ã†ãžã€‚ Maybeï¼Ÿ null ã‚ˆã‚Šå®‰å…¨ã«ã€Œå€¤ãŒãªã„ã“ã¨ã€ãŒæ‰±ãˆã‚‹ã‚‚ã®ã ã‚ˆ ã‚¹ã‚¿ãƒ¼ãƒˆåœ°ç‚¹ã¨ã—ã¦ã¯ã“ã‚Œã§ã„ã„ã§ã—ã‚‡ã†ã€‚ ä»¥é™ã§ã€ã€Œãªã‚“ã§å®‰å…¨ãªã®ï¼Ÿã€ã¨ã„ã†å…¨ã†ãªç–‘å•ã«ç”ãˆã¦ã¿ãŸã„ã¨æ€ã„ã¾ã™ã€‚ å•é¡Œç‚¹ int ã§èª¬æ˜Žã™ã‚‹ã¨ç…™ã«å·»ã„ã¦ã—ã¾ã†ã‚ˆã†ãªæ°—ãŒã—ãŸã®ã§ã€User ã‚¯ãƒ©ã‚¹ã‚’è¦‹ã¦ã¿ã¾ã™ã€‚ import java.util.*; class User { final String name;
somemo 2012/08/24
maybe

java

null
ãƒªãƒ³ã‚¯
1