{"id":335,"date":"2022-04-12T14:15:04","date_gmt":"2022-04-12T06:15:04","guid":{"rendered":"https:\/\/blog.lijiajia.top\/?p=335"},"modified":"2026-06-19T21:51:34","modified_gmt":"2026-06-19T13:51:34","slug":"java%e5%9f%ba%e7%a1%80%e7%9f%a5%e8%af%86-%e7%b1%bb%e5%92%8c%e5%af%b9%e8%b1%a1","status":"publish","type":"post","link":"https:\/\/blog.ttwow.top\/?p=335","title":{"rendered":"Java\u57fa\u7840\u77e5\u8bc6-\u7c7b\u548c\u5bf9\u8c61"},"content":{"rendered":"

\u7c7b\u548c\u5bf9\u8c61<\/h2>\n

\u5173\u7cfb\u56fe\uff1a<\/h3>\n

\"file\"<\/div><\/p>\n<\/p>\n

\u6f14\u53d8\u4ee3\u7801\uff1a<\/h3>\n
package chapter07;\n\npublic class Object01 {\n\n    \/\/\u7f16\u5199\u4e00\u4e2amain\u65b9\u6cd5\n    public static void main(String[] args) {\n\n        \/*\n        \u5f20\u8001\u592a\u517b\u4e86\u4e24\u53ea\u732b\u732b:\u4e00\u53ea\u540d\u5b57\u53eb\u5c0f\u767d,\u4eca\u5e743\u5c81,\u767d\u8272\u3002\n        \u8fd8\u6709\u4e00\u53ea\u53eb\u5c0f\u82b1,\u4eca\u5e74100\u5c81,\u82b1\u8272\u3002\u8bf7\u7f16\u5199\u4e00\u4e2a\u7a0b\u5e8f\uff0c\u5f53\u7528\u6237\u8f93\u5165\u5c0f\u732b\u7684\u540d\u5b57\u65f6\uff0c\n        \u5c31\u663e\u793a\u8be5\u732b\u7684\u540d\u5b57\uff0c\u5e74\u9f84\uff0c\u989c\u8272\u3002\u5982\u679c\u7528\u6237\u8f93\u5165\u7684\u5c0f\u732b\u540d\u9519\u8bef\uff0c\n        \u5219\u663e\u793a \u5f20\u8001\u592a\u6ca1\u6709\u8fd9\u53ea\u732b\u732b\u3002\n         *\/\n        \/\/\u5355\u72ec\u53d8\u91cf\u6765\u89e3\u51b3 => \u4e0d\u5229\u4e8e\u6570\u636e\u7684\u7ba1\u7406(\u4f60\u628a\u4e00\u53ea\u732b\u7684\u4fe1\u606f\u62c6\u89e3)\n        \/\/\u7b2c1\u53ea\u732b\u4fe1\u606f\n\n        \/\/ String cat1Name = "\u5c0f\u767d";\n        \/\/ int cat1Age = 3;\n        \/\/ String cat1Color = "\u767d\u8272";\n\n        \/\/ \/\/\u7b2c2\u53ea\u732b\u4fe1\u606f\n        \/\/ String cat2Name = "\u5c0f\u82b1";\n        \/\/ int cat2Age = 100;\n        \/\/ String cat2Color = "\u82b1\u8272";\n\n        \/\/\u6570\u7ec4 ===>(1)\u6570\u636e\u7c7b\u578b\u4f53\u73b0\u4e0d\u51fa\u6765(2) \u53ea\u80fd\u901a\u8fc7[\u4e0b\u6807]\u83b7\u53d6\u4fe1\u606f\uff0c\u9020\u6210\u53d8\u91cf\u540d\u5b57\u548c\u5185\u5bb9\n        \/\/         \u7684\u5bf9\u5e94\u5173\u7cfb\u4e0d\u660e\u786e(3) \u4e0d\u80fd\u4f53\u73b0\u732b\u7684\u884c\u4e3a\n        \/\/\u7b2c1\u53ea\u732b\u4fe1\u606f\n\n        \/\/ String[] cat1 = {"\u5c0f\u767d", "3", "\u767d\u8272"};\n        \/\/ String[] cat2 = {"\u5c0f\u82b1", "100", "\u82b1\u8272"};\n\n        \/\/\u4f7f\u7528OOP\u9762\u5411\u5bf9\u8c61\u89e3\u51b3\n        \/\/\u5b9e\u4f8b\u5316\u4e00\u53ea\u732b[\u521b\u5efa\u4e00\u53ea\u732b\u5bf9\u8c61]\n        \/\/\u8001\u97e9\u89e3\u8bfb\n        \/\/1. new Cat() \u521b\u5efa\u4e00\u53ea\u732b(\u732b\u5bf9\u8c61)\n        \/\/2. Cat cat1 = new Cat(); \u628a\u521b\u5efa\u7684\u732b\u8d4b\u7ed9 cat1\n        \/\/3. cat1 \u5c31\u662f\u4e00\u4e2a\u5bf9\u8c61\n        Cat cat1 = new Cat();\n        cat1.name = "\u5c0f\u767d";\n        cat1.age = 3;\n        cat1.color = "\u767d\u8272";\n        cat1.weight = 10;\n        \/\/\u521b\u5efa\u4e86\u7b2c\u4e8c\u53ea\u732b\uff0c\u5e76\u8d4b\u7ed9 cat2\n        \/\/cat2 \u4e5f\u662f\u4e00\u4e2a\u5bf9\u8c61(\u732b\u5bf9\u8c61)\n        Cat cat2 = new Cat();\n        cat2.name = "\u5c0f\u82b1";\n        cat2.age = 100;\n        cat2.color = "\u82b1\u8272";\n        cat2.weight = 20;\n\n        \/\/\u600e\u4e48\u8bbf\u95ee\u5bf9\u8c61\u7684\u5c5e\u6027\u5462\n        System.out.println("\u7b2c1\u53ea\u732b\u4fe1\u606f" + cat1.name\n                + " " + cat1.age + " " + cat1.color + " " + cat1.weight);\n\n        System.out.println("\u7b2c2\u53ea\u732b\u4fe1\u606f" + cat2.name\n                + " " + cat2.age + " " + cat2.color + " " + cat2.weight);\n    }\n}\n\n\/\/\u4f7f\u7528\u9762\u5411\u5bf9\u8c61\u7684\u65b9\u5f0f\u6765\u89e3\u51b3\u517b\u732b\u95ee\u9898\n\/\/\n\/\/\u5b9a\u4e49\u4e00\u4e2a\u732b\u7c7b Cat -> \u81ea\u5b9a\u4e49\u7684\u6570\u636e\u7c7b\u578b\nclass Cat {\n    \/\/\u5c5e\u6027\/\u6210\u5458\u53d8\u91cf\n    String name; \/\/\u540d\u5b57\n    int age; \/\/\u5e74\u9f84\n    String color; \/\/\u989c\u8272\n    double weight; \/\/\u4f53\u91cd\n\n    \/\/\u884c\u4e3a\n\n}\n<\/code><\/pre>\n
\u7c7b\u548c\u5bf9\u8c61\u7684\u533a\u522b\u548c\u8054\u7cfb<\/h3>\n
\u901a\u8fc7\u4e0a\u9762\u7684\u6848\u4f8b\u548c\u8bb2\u89e3\u6211\u4eec\u53ef\u4ee5\u770b\u51fa\uff1a
\n1)\u7c7b\u662f\u62bd\u8c61\u7684\uff0c\u6982\u5ff5\u7684\uff0c\u4ee3\u8868\u4e00\u7c7b\u4e8b\u7269\uff0c\u6bd4\u5982\u4eba\u7c7b\uff0c\u732b\u7c7b\uff0c\u5373\u5b83\u662f\u6570\u636e\u7c7b\u578b
\n2)\u5bf9\u8c61\u662f\u5177\u4f53\u7684\uff0c\u5b9e\u9645\u7684\uff0c\u4ee3\u8868\u4e00\u4e2a\u5177\u4f53\u4e8b\u7269\uff0c\u5373\u662f\u5b9e\u4f8b.
\n3)\u7c7b\u662f\u5bf9\u8c61\u7684\u6a21\u677f\uff0c\u5bf9\u8c61\u662f\u7c7b\u7684\u4e00\u4e2a\u4e2a\u4f53\uff0c\u5bf9\u5e94\u4e00\u4e2a\u5b9e\u4f8b<\/p>\n
\u5bf9\u8c61\u5728\u5185\u5b58\u4e2d\u5b58\u5728\u5f62\u5f0f<\/h3>\n
\"file\"<\/div><\/p>\n
\u5c5e\u6027\/\u6210\u5458\u53d8\u91cf<\/h3>\n
\u221a\u57fa\u672c\u4ecb\u7ecd
\n1.\u4ece\u6982\u5ff5\u6216\u53eb\u6cd5\u4e0a\u770b\uff1a\u6210\u5458\u53d8\u91cf=\u5c5e\u6027=field(\u5373\u6210\u635f\u53d8\u91cf\u662f\u7528\u6765\u8868\u793a\u5c5e\u6027\u7684)
\n2.\u5c5e\u6027\u662f\u7c7b\u7684\u4e00\u4e2a\u7ec4\u6210\u57f9\u90e8\u5206\uff0c\u4e00\u822c\u662f\u57fa\u672c\u6570\u636e\u7c7b\u578b\uff0c\u4e5f\u53ef\u662f\u5f15\u7528\u7c7b\u578b\uff08\u5bf9\u8c61\uff0c\u6570\u7ec4\uff09\u3002\u6bd4\u5982\u6211\u4eec\u524d\u9762\u5b9a\u4e49\u732b\u7c7b\u7684int age\u5c31\u662f\u5c5e\u6027<\/p>\n
\u25cf<\/p>\n
\u7c7b\u548c\u5bf9\u8c61\u7684\u5185\u5b58\u5206\u914d\u673a\u5236<\/h2>\n
\u221aJava\u5185\u5b58\u7684\u7ed3\u6784\u5206\u6790
\n\u6808\uff1a\u4e00\u822c\u5b58\u653e\u57fa\u672c\u6570\u636e\u7c7b\u578b\uff08\u5c40\u90e8\u53d8\u91cf\uff09
\n2.\u5806\uff1a\u5b58\u653e\u5bf9\u8c61(Cat cat,\u6570\u7ec4\u7b49)
\n3.\u65b9\u6cd5\u533a\uff1a\u5e38\u91cf\u6c60\uff08\u5e38\u91cf\uff0c\u6bd4\u5982\u5b57\u7b26\u4e32\uff09\uff0c\u7c7b\u52a0\u8f7d\u4fe1\u606f
\n4.\u793a\u610f\u56fe[Cat(name,age,price]
\n
\"file\"<\/div><\/p>\n
\u221aJava\u521b\u5efa\u5bf9\u8c61\u7684\u6d41\u7a0b\u7b80\u5355\u5206\u6790\uff1a
\nPerson p new Person();
\np.name="jack\u201d;
\np.age 10
\n1.\u5148\u52a0\u8f7dPerson\u7c7b\u4fe1\u606f\uff08\u5c5e\u6027\u548c\u65b9\u6cd5\u4fe1\u606f\uff0c\u53ea\u4f1a\u52a0\u8f7d\u4e00\u6b21\uff09
\n2.\u5728\u5806\u4e2d\u5206\u914d\u7a7a\u95f4\uff0c\u8fdb\u884c\u9ed8\u8ba4\u521d\u59cb\u5316\uff08\u770b\u89c4\u5219\uff09
\n3.\u628a\u5730\u5740\u8d4b\u7ed9p,P\u5c31\u6307\u5411\u5bf9\u8c61
\n4.\u8fdb\u884c\u6307\u5b9a\u521d\u59cb\u5316\uff0c\u6bd4\u5982p.name="jack" p.age=10<\/p>\n
\u7ec3\u4e60<\/h3>\n
        Person a = new Person();\n        a.age = 10;\n        a.name = "\u5c0f\u7c73";\n        Person b;\n        b = a;\n        System.out.println(b.name);\n        b.age = 200;\n        b = null;\n        System.out.println(a.age);\n        System.out.println(b.age);<\/code><\/pre>\n
\u7ed3\u679c\uff1a<\/p>\n
\u5c0f\u7c73\n200\nException in thread "main" java.lang.NullPointerException\n    at chapter07.Object03.main(Object03.java:26)<\/code><\/pre>\n
\u5206\u6790\u56fe\uff1a
\n
\"file\"<\/div><\/p>\n
\u65b9\u6cd5\u8c03\u7528\u673a\u5236<\/h2>\n
\"file\"<\/div><\/p>\n","protected":false},"excerpt":{"rendered":"
\u7c7b\u548c\u5bf9\u8c61 \u5173\u7cfb\u56fe\uff1a \u6f14\u53d8\u4ee3\u7801\uff1a package chapter07; public class Object0 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[125],"tags":[86,90],"class_list":["post-335","post","type-post","status-publish","format-standard","hentry","category-java-backend","tag-86","tag-90"],"_links":{"self":[{"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/posts\/335","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=335"}],"version-history":[{"count":1,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/posts\/335\/revisions"}],"predecessor-version":[{"id":2180,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=\/wp\/v2\/posts\/335\/revisions\/2180"}],"wp:attachment":[{"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=335"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=335"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ttwow.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=335"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}