{"id":106235,"date":"2020-05-23T11:36:14","date_gmt":"2020-05-23T03:36:14","guid":{"rendered":"http:\/\/4563.org\/?p=106235"},"modified":"2020-05-23T11:36:14","modified_gmt":"2020-05-23T03:36:14","slug":"optional-ofnullablemap-getxxx-orelse-tostring%e6%9c%89%e6%9b%b4%e7%ae%80%e6%b4%81-map-%e5%8f%96%e5%80%bc-tostring-%e6%96%b9%e6%b3%95%e5%90%97","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=106235","title":{"rendered":"Optional.ofNullable(map.get(“xxx”)).orElse(“”).toString();\u6709\u66f4\u7b80\u6d01 Map \u53d6\u503c toString \u65b9\u6cd5\u5417"},"content":{"rendered":"
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Optional.ofNullable(map.get(“xxx”)).orElse(“”).toString();\u6709\u66f4\u7b80\u6d01 Map \u53d6\u503c toString \u65b9\u6cd5\u5417 <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span> <\/i> 3<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
getOrDefault <\/div>\n
\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (10<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : watermelon11 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    map.getOrDefault \u4e0d\u884c\u5417 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : wangyanrui <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    get or default \u8981\u6c42 map \u7684 value \u7c7b\u578b\u90fd\u662f string\uff0c\u6709\u4e00\u70b9\u4e0d\u5408\u4e3b\u8981\u6c42\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : ChanKc <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @ChanKc \u8fd8\u5728\u8fd9\u9650\u5236\uff1f\u6211\u600e\u4e48\u4e0d\u77e5\u9053 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : handong970123 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @wangyanrui @watermelon11
    getOrDefault() is not exactly the same as he wanted.
    getOrDefault \u662f\u8bf4, \u5982\u679c key \u4e0d\u5728, \u7ed9 default.
    \u800c OP \u7684\u95ee\u9898, \u6709\u53ef\u80fd key”XXX”\u5b58\u5728, \u503c\u662f null <\/div>\n<\/p><\/div>\n<\/li>\n
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    \u8cc7\u6df1\u5927\u4f6c : KentY <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5982\u679c map \u7684 VALUE \u662f String \u7c7b\u578b\uff0c\u5219\u4e0d\u8981 toString\uff0c\u5426\u5219 orElse(“”) \u4e0d\u4f1a\u901a\u8fc7\u7f16\u8bd1\u3002
    Optional.ofNullable(map.get(“xxx”)).map(Object::toString).orElse(“”); \u5982\u679c\u8981\u7528 Optional \u662f\u8fd9\u6837\uff1b
    \u5982\u679c\u662f\u6211\u5c31\u81ea\u5df1\u5c01\u4e00\u4e2a\u65b9\u6cd5 toStringOrEmpty(String stringOrNull) <\/div>\n<\/p><\/div>\n<\/li>\n
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    \u8cc7\u6df1\u5927\u4f6c : aguesuka <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @handong970123 \u6211\u8868\u8ff0\u6709\u70b9\u95ee\u9898\u2026\u8bd5\u60f3\u4e00\u4e2a Map<String, Person>\uff0cget Or default \u7684\u90a3\u4e2a default \u5e94\u8be5\u53ea\u80fd\u662f Person \u800c\u4e0d\u662f String\uff0c\u5982\u679c\u8981\u62ff String \u90a3\u4e48\u6cdb\u578b\u7684 value \u7c7b\u578b\u5e94\u8be5\u4e5f\u8981 String \u3002\u4e0d\u7528\u6cdb\u578b\u5f53\u6211\u6ca1\u8bf4 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : ChanKc <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    java.util.Objects#toString(Object, String) <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : lxk11153 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    Optional.ofNullable(map.get(“xxx”)).map(Object::toString).orElse(“”); <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : keshawnvan <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u601d\u8003\u8fd9\u4e2a\u95ee\u9898\u4f1a\u611f\u53d7\u5230 kotlin \u6bd4 java \u7684\u7b80\u6d01\u660e\u4e86. <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : KentY <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6765\u5199 Scala \u5427\uff1a<\/p>\n

    map.getOrElse(“xxx”, “”).toString<\/p>\n

    map.get(“xxx”) match {
    case Some(x) => x.toString
    case None => “”
    } <\/div>\n<\/p><\/div>\n<\/li>\n

  • \n","protected":false},"excerpt":{"rendered":"

    Optional.ofNullab…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/106235"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=106235"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/106235\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=106235"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=106235"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=106235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}