{"id":5358,"date":"2024-09-18T15:01:01","date_gmt":"2024-09-18T07:01:01","guid":{"rendered":""},"modified":"2024-09-18T15:01:01","modified_gmt":"2024-09-18T07:01:01","slug":"\u3010\u5468\u4e00\u901a\u52e4\u7535\u53f0\u3011Java8-15\u7684\u65b0\u7279\u6027\uff0c\u4f60\u77e5\u9053\u51e0\u4e2a\uff1f","status":"publish","type":"post","link":"https:\/\/mushiming.com\/5358.html","title":{"rendered":"\u3010\u5468\u4e00\u901a\u52e4\u7535\u53f0\u3011Java8-15\u7684\u65b0\u7279\u6027\uff0c\u4f60\u77e5\u9053\u51e0\u4e2a\uff1f"},"content":{"rendered":"<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"display: none;\"> \n <path stroke-linecap=\"round\" d=\"M5,0 0,2.5 5,5z\" id=\"raphael-marker-block\" style=\"-webkit-tap-highlight-color: rgba(0, 0, 0, 0);\"><\/path> \n<\/svg> <\/p>\n<h3>0. \u9605\u8bfb\u5b8c\u672c\u6587\u4f60\u5c06\u4f1a\u5b66\u5230<\/h3>\n<ul>\n<li>6\u4e2a\u5b9e\u7528\u7684Java\u65b0\u7279\u6027<\/li>\n<\/ul>\n<p>\u672c\u6587\u4e00\u5171\u7ea61760\u5b57,\u9605\u8bfb\u65f6\u957f\u5927\u6982\u7b49\u4e8e\u4e00\u9996Enrique Iglesias\u7684\u300aRing My Bells\u300b\u3002<\/p>\n<p>\u81ea\u4ece2018\u5e74\u5f00\u59cb\uff0cJava\u91c7\u7528\u4e86\u6bcf\u516d\u4e2a\u6708\u53d1\u5e03\u4e00\u6b21\u65b0\u7248\u672c\u7684\u7b56\u7565\u3002\u8fd9\u6837\u7684\u7b56\u7565\u4f7f\u5f97Java\u4fdd\u6301\u4e86\u65b0\u9c9c\u611f\u4ee5\u53ca\u5f3a\u52b2\u7684\u751f\u547d\u529b\uff0c\u5728\u8fd9\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5c06\u4f1a\u4e3a\u5927\u5bb6\u5e26\u67656\u4e2a\u5b9e\u7528\u7684Java\u65b0\u7279\u6027\u3002<\/p>\n<h3>1. Optioal\u7c7b<\/h3>\n<p>NullPointerException\u662fJava\u6240\u6709\u5f02\u5e38\u4e2d\u6700\u7ecf\u5178\u7684\u4e00\u79cd\u3002\u5927\u5bb6\u80af\u5b9a\u5bf9\u5b83\u4e0d\u964c\u751f\uff0c\u5b83\u7ecf\u5e38\u51fa\u4e4e\u610f\u6599\u5730\u51fa\u73b0\uff0c\u8ba9\u4eba\u5934\u75bc\u4e0d\u5df2\u3002\u597d\u5728Java 8\u4e3a\u6211\u4eec\u5f15\u5165\u4e86Optional\u7c7b\uff0cJava 10\u5b8c\u5584\u4e86\u8fd9\u4e00\u673a\u5236\u3002<\/p>\n<p>\u4ece\u672c\u8d28\u4e0a\u8bb2\uff0cOptional\u7c7b\u5141\u8bb8\u4f60\u5305\u88c5\u4e00\u4e2a\u53d8\u91cf\uff0c\u7136\u540e\u4f7f\u7528\u5305\u88c5\u5668\u7684\u65b9\u6cd5\u6765\u66f4\u7b80\u6d01\u5730\u5904\u7406Null\u7684\u95ee\u9898\u3002<\/p>\n<p>\u4e0b\u9762\u6211\u4eec\u770b\u4e00\u4e2a\u5bf9\u7167\u7684\u4f8b\u5b50\uff1a<\/p>\n<p><strong>\u4f8b1.1 \u672a\u4f7f\u7528Optional\u7c7b\u7684\u7a7a\u6307\u9488<\/strong><\/p>\n<pre class=\"language-java prettyprint linenums\"><code>public class MyClass { public static void main(String args[]) { InnerClass innerClass = null; \/\/ \u8fd9\u91cc\u5bf9\u5f15\u7528\u4e3anull\u7684\u53d8\u91cf\u8fdb\u884c\u4e86\u65b9\u6cd5\u8bbf\u95ee\uff0c\u4ea7\u751f\u4e00\u4e2aNullPointerException System.out.println(\"innerClass = \" + innerClass.getName()); } } class InnerClass { String name = \"\"; public String getName() { return this.name; } } <\/code><\/pre>\n<p>\u73b0\u5728\u6211\u4eec\u5982\u4f55\u4f7f\u7528Optional\u6765\u907f\u514d\u4e0a\u9762\u60c5\u51b5\u7684\u51fa\u73b0\u5462\uff1f<\/p>\n<p>Optional\u7c7b\u6709\u4e00\u4e2aisPresent()\u65b9\u6cd5\uff0c\u4f60\u53ef\u4ee5\u62ff\u5b83\u505a\u4e00\u4e2aif-check\u3002\u4f46\u662f\u6211\u4eec\u7531\u66f4\u7b80\u77ed\u7684\u65b9\u6cd5\u2014\u2014ifPresent()\uff0c\u53ea\u6709\u5728\u503c\u5b58\u5728\u7684\u60c5\u51b5\u4e0b\u624d\u4f1a\u7ee7\u7eed\u8fd0\u884c\u4ee3\u7801\u3002<\/p>\n<p><strong>\u4f8b1.2 \u4f7f\u7528Optional\u7c7b\u7684\u7a7a\u6307\u9488<\/strong><\/p>\n<pre class=\"language-java prettyprint linenums\"><code>public class MyClass { public static void main(String args[]) { InnerClass innerClass = null; Optional fooWrapper = Optional.ofNullable(in<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"\u3010\u5468\u4e00\u901a\u52e4\u7535\u53f0\u3011Java8-15\u7684\u65b0\u7279\u6027\uff0c\u4f60\u77e5\u9053\u51e0\u4e2a\uff1f0.\u9605\u8bfb\u5b8c\u672c\u6587\u4f60\u5c06\u4f1a\u5b66\u52306\u4e2a\u5b9e\u7528\u7684Java\u65b0\u7279\u6027\u672c\u6587\u4e00\u5171\u7ea61760\u5b57,\u9605\u8bfb\u65f6\u957f\u5927\u6982...","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"_links":{"self":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/5358"}],"collection":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/comments?post=5358"}],"version-history":[{"count":0,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/5358\/revisions"}],"wp:attachment":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/media?parent=5358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/categories?post=5358"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/tags?post=5358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}