{"id":461288,"date":"2024-04-02T08:48:21","date_gmt":"2024-04-02T07:48:21","guid":{"rendered":"https:\/\/blog.jetbrains.com\/?post_type=idea&p=461288"},"modified":"2024-04-02T08:48:26","modified_gmt":"2024-04-02T07:48:26","slug":"easy-hacks-how-to-create-inheritance-in-java","status":"publish","type":"idea","link":"https:\/\/blog.jetbrains.com\/zh-hans\/idea\/2024\/04\/easy-hacks-how-to-create-inheritance-in-java\/","title":{"rendered":"\u7b80\u5355\u653b\u7565\uff1a\u5728 Java \u4e2d\u521b\u5efa\u7ee7\u627f"},"content":{"rendered":"

\u5728 Java \u548c\u5176\u4ed6\u7f16\u7a0b\u8bed\u8a00\u4e2d\uff0c\u7ee7\u627f\u662f\u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u7684\u57fa\u672c\u7279\u6027\u4e4b\u4e00\u3002 \u501f\u52a9\u7ee7\u627f\uff0c\u60a8\u53ef\u4ee5\u521b\u5efa\u4ece\u7c7b\uff08\u57fa\u7c7b\u6216\u8d85\u7c7b\uff09\u6d3e\u751f\u7684\u7c7b\uff0c\u5e76\u91cd\u7528\u3001\u6269\u5c55\u6216\u4fee\u6539\u8d85\u7c7b\u7684\u884c\u4e3a\u3002 \u8fd9\u4e00\u539f\u5219\u5141\u8bb8\u60a8\u6784\u5efa\u7c7b\u5c42\u6b21\u7ed3\u6784\u548c\u91cd\u7528\u73b0\u6709\u4ee3\u7801\u3002<\/p>\n

Java \u672c\u8eab\u5230\u5904\u90fd\u4f7f\u7528\u7ee7\u627f\uff1a\u8bb8\u591a JDK \u7c7b\u7ee7\u627f\u5176\u4ed6\u7c7b\uff0c\u5e76\u4e14 Java \u4e2d\u7684\u6bcf\u4e2a\u7c7b\u90fd\u9690\u5f0f\u6269\u5c55 java.lang.Object<\/code>\u3002 \u672c\u6587\u4e0d\u4f1a\u8fc7\u591a\u5173\u6ce8\u8fd9\u4e00\u90e8\u5206\uff0c\u800c\u4e3b\u8981\u4e3e\u4f8b\u8bf4\u660e\u5982\u4f55\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528\u7ee7\u627f\u3002<\/p>\n

\u5047\u8bbe\uff0c\u60a8\u60f3\u8981\u5728\u5e94\u7528\u7a0b\u5e8f\u4e2d\u521b\u5efa Employee<\/code> \u548c Customer<\/code> \u7c7b\u3002 \u501f\u52a9\u7ee7\u627f\uff0c\u60a8\u53ef\u4ee5\u7f16\u5199\u8fd9\u4e24\u4e2a\u7c7b\uff0c\u4f7f\u5176\u4ece\u7236 Person<\/code> \u7c7b\u7ee7\u627f name<\/code> \u548c address<\/code> \u5c5e\u6027\u3002 \u5728\u4ee3\u7801\u53ef\u91cd\u7528\u6027\u548c\u6a21\u5757\u5316\u65b9\u9762\uff0c\u8fd9\u6709\u591a\u4e2a\u597d\u5904\uff0c\u672c\u6587\u5c06\u5177\u4f53\u4ecb\u7ecd\u3002<\/p>\n

\u4ec0\u4e48\u662f Java \u4e2d\u7684\u7ee7\u627f\uff1f<\/h2>\n

\u4ecd\u7136\u662f\u524d\u8a00\u4e2d\u7684\u793a\u4f8b\uff1a\u5177\u6709 Person<\/code>\u3001Employee<\/code> \u548c Customer<\/code> \u7c7b\u7684\u5c42\u6b21\u7ed3\u6784\u3002 Person<\/code> \u7c7b\u5e26\u6709\u4e00\u4e2a name<\/code> \u5c5e\u6027\u3001\u8be5\u5c5e\u6027\u7684 getter \u548c\u4e00\u4e2a\u6784\u9020\u51fd\u6570\uff1a<\/p>\n

public class Person {\n    private final String name;\n\n    public Person(String name) {\n        this.name = name;\n    }\n\n    public String getName() {\n        return name;\n    }\n}<\/pre>\n
\u5982\u679c\u8981\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528 Person<\/code> \u7c7b\uff0c\u53ef\u4ee5\u4ece\u4e2d\u5b9e\u4f8b\u5316\u4e00\u4e2a\u65b0\u5bf9\u8c61\uff0c\u4f8b\u5982\uff0c\u5c06\u5176\u540d\u79f0\u6253\u5370\u5230\u63a7\u5236\u53f0\uff1a<\/p>\n
var person = new Person(\"Maarten\");\nSystem.out.println(person.getName());\n\n\/\/ Prints: Maarten<\/pre>\n
Employee<\/code> \u7c7b\u9700\u8981\u4e00\u4e2a name<\/code> \u548c\u4e00\u4e2a employeeId<\/code> \u5c5e\u6027\u3002 \u7531\u4e8e Employee<\/code> \u4e0e\u4eba\u5171\u4eab\u8bb8\u591a\u7279\u5f81\uff08\u81f3\u5c11\u5728\u673a\u5668\u4eba\u62a2\u8d70\u6240\u6709\u5de5\u4f5c\u4e4b\u524d\uff09\uff0c\u60a8\u53ef\u4ee5\u91cd\u7528 Person<\/code> \u7c7b\u4f5c\u4e3a\u57fa\u7840\u3002<\/p>\n
\u5728 Java \u4e2d\uff0c\u57fa\u7c7b\u901a\u5e38\u88ab\u79f0\u4e3a\u8d85\u7c7b<\/em>\uff0c\u800c\u7ee7\u627f\u81ea\u5b83\u7684\u7c7b\u88ab\u79f0\u4e3a\u5b50\u7c7b<\/em>\u3002 \u60a8\u4e5f\u53ef\u80fd\u9047\u5230\u5176\u4ed6\u672f\u8bed\u7528\u6cd5\uff0c\u4f8b\u5982\u4f7f\u7528\u7236\u7c7b<\/em>\u6307\u4ee3\u8d85\u7c7b\u3002<\/p>\n
\u4ee5 Employee<\/code> \u7c7b\u4e3a\u4f8b\uff0c\u5b83\u7ee7\u627f\u81ea Person<\/code> \u7c7b\uff1a<\/p>\n
public class Employee extends Person {\n    private final int employeeId;\n\n    public Employee(String name, int employeeId) {\n        super(name);\n        this.employeeId = employeeId;\n    }\n\n    public int getEmployeeId() {\n        return employeeId;\n    }\n}<\/pre>\n
\u6709\u51e0\u70b9\u9700\u8981\u5c55\u5f00\u8bf4\u660e\u3002 \u9996\u5148\uff0cextends<\/code> \u5173\u952e\u5b57\u7528\u4e8e\u544a\u8bc9 Java \u7f16\u8bd1\u5668 Employee extends Person<\/code>\u3002 \u63a5\u4e0b\u6765\uff0c\u5728 Employee<\/code> \u6784\u9020\u51fd\u6570\u4e2d\uff0c\u53ef\u4ee5\u770b\u5230 super(name)<\/code> \u8bed\u6cd5\u5c06 name<\/code> \u5f62\u53c2\u4f20\u9012\u5230\u8d85\u7c7b\u6784\u9020\u51fd\u6570\u4e2d\uff0c\u4f7f\u5e95\u5c42 Person<\/code> \u53ef\u4ee5\u5b58\u50a8\u6b64\u5c5e\u6027\u503c\u3002<\/p>\n
\u6709\u8da3\u7684\u662f\uff0c\u56e0\u4e3a\u6211\u4eec\u4f7f\u7528\u7ee7\u627f\uff0cEmployee<\/code> \u4e0d\u5fc5\u5b9e\u73b0 name<\/code>\u3002 \u7136\u800c\uff0cEmployee<\/code> \u7c7b\u73b0\u5728\u516c\u5f00\u4e24\u4e2a\u5c5e\u6027\uff1aname<\/code> \u548c employeeId<\/code>\uff1a<\/p>\n
var employee = new Employee(\"Maarten\", 123);\nSystem.out.printf(\"%s (%s)\", employee.getName(), employee.getEmployeeId());\n\n\/\/ Prints: Maarten (123)<\/pre>\n
\u7c7b\u4f3c\u5730\uff0c\u60a8\u53ef\u4ee5\u521b\u5efa\u4e00\u4e2a\u540c\u6837\u6269\u5c55 Person<\/code> \u7684 Customer<\/code> \u7c7b\uff0c\u5e76\u6dfb\u52a0 String<\/code> \u7c7b\u578b\u7684 customerId<\/code> \u5c5e\u6027\uff1a<\/p>\n
public class Customer extends Person {\n    private final String customerId;\n\n    public Customer(String name, String customerId) {\n        super(name);\n        this.customerId = customerId;\n    }\n\n    public String getCustomerId() {\n        return customerId;\n    }\n}<\/pre>\n
\u4f7f\u7528 Customer<\/code> \u7c7b\u65f6\uff0c\u60a8\u5c06\u4ece Person<\/code> \u8d85\u7c7b\u83b7\u53d6 name<\/code> \u5c5e\u6027\u53ca\u5176 getter\uff1a<\/p>\n
var customer = new Customer(\"Maarten\", \"ABC\");\nSystem.out.printf(\"%s (%s)\", customer.getName(), customer.getCustomerId());\n\n\/\/ Prints: Maarten (ABC)<\/pre>\n
\u5982\u6b64\u793a\u4f8b\u6240\u793a\uff0c\u7ee7\u627f\u8ba9\u60a8\u53ef\u4ee5\u5728\u4efb\u4f55\u5b50\u7c7b\u4e2d\u91cd\u7528\u8d85\u7c7b\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\u3002<\/p>\n
\u5982\u679c\u60a8\u4f7f\u7528 IntelliJ IDEA Ultimate\uff0c\u53ef\u4ee5\u4ece\u8fd9\u4e9b\u7c7b\u521b\u5efa UML \u56fe<\/a>\u5e76\u76f4\u89c2\u5448\u73b0\u6211\u4eec\u521a\u521a\u521b\u5efa\u7684\u5c42\u6b21\u7ed3\u6784\u3002 \u5728 Windows\/Linux \u4e0a\u4f7f\u7528 Ctrl+Alt+Shift+D<\/em> \u5feb\u6377\u952e\uff0c\u6216\u5728 macOS \u4e0a\u4f7f\u7528 \u2318\u0421md+\u2325Opt+\u21e7Shift+U<\/em>\uff0c\u6216\u8005\u4f7f\u7528 Project<\/em>\uff08\u9879\u76ee\uff09\u5de5\u5177\u7a97\u53e3\u4e2d\u8f6f\u4ef6\u5305\u6216\u7c7b\u4e0a\u7684\u4e0a\u4e0b\u6587\u83dc\u5355\uff1a<\/p>\n
\"\"<\/figure>\n
\u63d0\u793a\uff1a\u4f7f\u7528\u5de5\u5177\u680f\u4e2d\u7684\u56fe\u6807\u5207\u6362\u662f\u5426\u663e\u793a\u5b57\u6bb5\u3001\u6784\u9020\u51fd\u6570\u3001\u65b9\u6cd5\u6216\u5c5e\u6027\u3002<\/em><\/p>\n
\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u60a8\u53ef\u80fd\u60f3\u6709\u4e00\u4e2a\u65e0\u6cd5\u5b9e\u4f8b\u5316\u7684\u901a\u7528\u8d85\u7c7b\u548c\u53ef\u4ee5\u5b9e\u4f8b\u5316\u7684\u5b50\u7c7b\u3002 \u5982\u679c\u6709\u901a\u7528\u5c5e\u6027\u6216\u65b9\u6cd5\uff0c\u8fd9\u5f88\u6709\u7528\uff0c\u4f46\u5982\u679c\u6ca1\u6709\u5b50\u7c7b\uff0c\u76f4\u63a5\u4f7f\u7528\u8d85\u7c7b\u4e5f\u6ca1\u6709\u610f\u4e49\u3002 \u5728 Java \u4e2d\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 abstract<\/code> \u4fee\u9970\u7b26\u544a\u8bc9\u7f16\u8bd1\u5668\u53ef\u4ee5\u4f7f\u7528\u7c7b\u578b\u540d\u79f0\u5e76\u4e14\u53ef\u4ee5\u7ee7\u627f\u7c7b\uff0c\u4f46\u60a8\u4e0d\u4f1a\u60f3\u76f4\u63a5\u521b\u5efa\u65b0\u5bf9\u8c61\uff1a<\/p>\n
public abstract class Person { } \/\/ can be inherited from, but not instantiated\nnew Person(); \/\/ does not work\npublic class Employee extends Person { } \/\/ can be inherited from & instantiated\nnew Employee(); \/\/ works\npublic class Customer extends Person { } \/\/ can be inherited from & instantiated\nnew Customer(); \/\/ works<\/pre>\n
\u9664\u4e86\u62bd\u8c61\u7c7b\u5916\uff0c\u60a8\u8fd8\u53ef\u4ee5\u5b9a\u4e49\u548c\u7ee7\u627f\u63a5\u53e3\u3002 \u867d\u7136\u62bd\u8c61\u7c7b\u901a\u5e38\u5e94\u5305\u542b\u5176\u67d0\u4e9b\u6210\u5458\u7684\u57fa\u672c\u5b9e\u73b0\uff0c\u4f46\u63a5\u53e3\u66f4\u52a0\u8f7b\u91cf\u3002 \u63a5\u53e3\u5b9a\u4e49\u4e86\u5176\u5b50\u7c7b\u4e0a\u53ef\u7528\u7684\u6210\u5458\uff0c\u4f46\u4e0d\u6dfb\u52a0\u5b9e\u73b0\u3002 \u5b83\u4eec\u5f88\u50cf\u4e00\u4e2a\u534f\u5b9a\u3002<\/p>\n
\u5982\u679c\u5c06 Person<\/code> \u91cd\u5199\u4e3a\u63a5\u53e3\uff0c\u5219\u53ef\u4ee5\u5411\u4ee3\u7801\u7684\u4f7f\u7528\u8005\u4f20\u8fbe Person<\/code> \u5b9e\u73b0\u5c06\u5177\u6709 name<\/code> \u5c5e\u6027\u7684 getter\u3002 \u4e0d\u8fc7\uff0c\u6ca1\u6709\u8be5 getter \u7684\u5b9e\u73b0\uff0c\u4e5f\u6ca1\u6709\u5305\u542b\u8be5\u540d\u79f0\u7684\u652f\u6301\u5b57\u6bb5\u3002 \u76f8\u53cd\uff0c\u63a5\u53e3\u7684\u5b9e\u73b0\u5fc5\u987b\u63d0\u4f9b\uff1a<\/p>\n
public interface Person {\n  String getName(); \/\/ consumers can expect this getter to exist, and subclasses have to provide an implementation\n}\n\nclass Employee implements Person {\n\n  @Override\n  public String getName() {\n      return \"\"; \/\/ may need a backing field, constructor, ...\n  }\n}<\/pre>\n
\u6ce8\u610f\uff0c\u8fd9\u91cc\u4e0d\u662f\u4f7f\u7528 extends<\/code> \u5173\u952e\u5b57\uff0c\u800c\u662f\u4f7f\u7528 implements<\/code> \u5173\u952e\u5b57\u7ee7\u627f\u63a5\u53e3\u3002<\/p>\n
\u4e0b\u9762\u6211\u4eec\u6765\u70b9\u66f4\u6709\u610f\u601d\u7684\uff01<\/p>\n
\u91cd\u5199 Java \u7c7b\u7684\u65b9\u6cd5<\/h2>\n
\u5728\u7c7b\u5c42\u6b21\u7ed3\u6784\u4e2d\uff0c\u5b50\u7c7b\u53ef\u4ee5\u91cd\u5199\u8d85\u7c7b\u7684\u884c\u4e3a\u3002 \u6211\u4eec\u7a0d\u5fae\u6269\u5c55\u4e00\u4e0b\u793a\u4f8b\uff0c\u5411 Employee<\/code> \u7c7b\u6dfb\u52a0\u4e00\u4e2a title<\/code> \u5c5e\u6027\u53ca\u5176 getter\u3002<\/p>\n
\u63d0\u793a\uff1a\u5728 Employee<\/code> \u7684\u6784\u9020\u51fd\u6570\u4e2d\u6dfb\u52a0 String title<\/code> \u4f5c\u4e3a\u5b9e\u53c2\u65f6\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 Alt+Enter (Windows\/Linux) \u6216 \u2325Opt+Enter (macOS) \u8ba9 IntelliJ IDEA \u521b\u5efa\u5b57\u6bb5\u5e76\u66f4\u65b0\u73b0\u6709\u7528\u6cd5\uff1a<\/em><\/p>\n
\"\"<\/figure>\n
\u66f4\u65b0\u540e\u7684 Employee<\/code>\uff1a<\/p>\n
public class Employee extends Person {\n    private final String title;\n    private final int employeeId;\n\n    public Employee(String name, String title, int employeeId) {\n        super(name);\n        this.title = title;\n        this.employeeId = employeeId;\n    }\n\n    public int getEmployeeId() {\n        return employeeId;\n    }\n\n    public String getTitle() {\n        return title;\n    }\n}<\/pre>\n
Employee<\/code> \u7c7b\u73b0\u5728\u53ef\u4ee5\u4ee3\u8868\u5404\u4f4d\u5458\u5de5\uff0c\u5305\u542b\u5458\u5de5\u7684\u5934\u8854\u548c ID\uff1a<\/p>\n
var employee1 = new Employee(\"Maarten\", \"Developer Advocate\", 123);\nvar employee2 = new Employee(\"Hadi\", \"Developer Advocate\", 456);<\/pre>\n
\u5c31\u5c42\u6b21\u7ed3\u6784\u800c\u8a00\uff0cEmployee<\/code> \u662f\u4e00\u4e2a\u5f88\u597d\u7684\u4f8b\u5b50\u3002 \u4f46\u95ee\u9898\u662f\uff1aHadi \u5b9e\u9645\u662f\u56e2\u961f\u4e3b\u7ba1\uff0c\u800c\u4e0d\u4ec5\u4ec5\u662f Employee<\/code>\u3002 \u600e\u6837\u624d\u80fd\u4f53\u73b0\u8fd9\u4e00\u70b9\u5462\uff1f \u4f7f\u7528\u66f4\u591a\u7ee7\u627f\uff01 \u6211\u4eec\u6765\u5f15\u5165\u4e00\u4e2a\u7ee7\u627f\u81ea Employee<\/code> \u7684 TeamLead<\/code> \u5b50\u7c7b\uff0c\u5e76\u4e14\u59cb\u7ec8\u7ed9 title<\/code> \u7684 getter \u8fd4\u56de\u503c\u52a0\u4e0a\u201c(team lead)\u201d\u540e\u7f00\uff1a<\/p>\n
public class TeamLead extends Employee {\n\n    public TeamLead(String name, String title, int employeeId) {\n        super(name, title, employeeId);\n    }\n\n    @Override\n    public String getTitle() {\n        return super.getTitle() + \" (team lead)\";\n    }\n}<\/pre>\n
TeamLead<\/code> \u7c7b\u7684\u5b9e\u73b0\u975e\u5e38\u7b80\u5355\uff1a\u5b83\u91cd\u7528 Employee<\/code> \u8d85\u7c7b\u4e2d\u7684\u6240\u6709\u4ee3\u7801\u3002 \u4e0d\u8fc7\uff0c\u5b83\u4f1a\u91cd\u5199<\/em> getTitle()<\/code> getter \u5b9e\u73b0\uff1a<\/p>\n
    \n
  • @Override<\/code> \u6ce8\u89e3\u901a\u77e5 Java \u7f16\u8bd1\u5668\u60a8\u6b63\u5728\u91cd\u5199\u8d85\u7c7b\u4e2d\u7684\u65b9\u6cd5\u3002 \u8fd9\u6709\u52a9\u4e8e\u7f16\u8bd1\u5668\u5728\u65b9\u6cd5\u4e0d\u5b58\u5728\u6216\u4e0d\u5177\u6709\u4e0e\u57fa\u7c7b\u76f8\u540c\u7684\u7b7e\u540d\u65f6\u53d1\u51fa\u8b66\u544a\u3002<\/li>\n
  • \u4f7f\u7528 super.getTitle()<\/code> \u4ece Employee<\/code> \u8c03\u7528 getter\uff0c\u7136\u540e\u91cd\u5199\u7248\u672c\uff0c\u5728\u8fd4\u56de\u503c\u4e4b\u524d\u9644\u52a0\u4e00\u4e2a\u540e\u7f00\u3002<\/li>\n<\/ul>\n
    \u60a8\u53ef\u4ee5\u4f7f\u7528 TeamLead<\/code> \u7c7b\u5e76\u67e5\u770b\u6253\u5370\u5230\u63a7\u5236\u53f0\u7684\u540e\u7f00\uff1a<\/p>\n
    var employee = new TeamLead(\"Hadi\", \"Developer Advocate\", 456);\n\nSystem.out.printf(\"%s (%s) - %s\", employee.getName(), employee.getEmployeeId(), employee.getTitle());\n\n\/\/ Prints: Hadi (456) - Developer Advocate (team lead)<\/pre>\n
    \u4f7f\u7528 final<\/code> \u4fee\u9970\u7b26\u9632\u6b62\u7ee7\u627f<\/h2>\n
    \u4fd7\u8bdd\u8bf4\uff1a\u201c\u80fd\u529b\u8d8a\u5927\uff0c\u8d23\u4efb\u8d8a\u5927\u201d\uff0c\u7ee7\u627f\u4e5f\u662f\u5982\u6b64\u3002 \u4e00\u4e2a\u8d85\u7c7b\u53ef\u4ee5\u6709\u65e0\u9650\u4e2a\u5b50\u7c7b\uff0c\u4f46\u8fd9\u4e0d\u4e00\u5b9a\u662f\u7406\u60f3\u9009\u62e9\u3002 \u5728\u6211\u4eec\u7684\u793a\u4f8b\u4e2d\uff0c\u60a8\u53ef\u80fd\u60f3\u963b\u6b62 TeamLead<\/code> \u62e5\u6709\u66f4\u591a\u5b50\u7c7b\u6216\u5b8c\u5168\u963b\u6b62\u4ece\u67d0\u4e2a\u7c7b\u7ee7\u627f\u3002<\/p>\n
    \u5728 Java \u4e2d\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 final<\/code> \u4fee\u9970\u7b26\u8bbe\u7f6e\u53ef\u6269\u5c55\u6027\u7684\u9650\u5236\u3002 \u60a8\u53ef\u80fd\u5df2\u7ecf\u6ce8\u610f\u5230 final<\/code> \u88ab\u7528\u4e8e Person<\/code> \u4e2d\u7684 name<\/code> \u5c5e\u6027\uff0c\u4f7f\u5176\u6210\u4e3a\u201c\u53ea\u8bfb\u201d\u5e76\u907f\u514d\u88ab\u91cd\u65b0\u8d4b\u503c\u3002<\/p>\n
    final<\/code> \u4fee\u9970\u7b26\u4e5f\u53ef\u4ee5\u4e0e\u7ee7\u627f\u4e00\u8d77\u4f7f\u7528\u3002 \u5f53 final<\/code> \u5e94\u7528\u4e8e\u7c7b\u65f6\uff0c\u5c06\u65e0\u6cd5\u4ece\u5b83\u7ee7\u627f\u3002 \u4f8b\u5982\uff0c\u5411 Employee<\/code> \u7c7b\u6dfb\u52a0 final<\/code> \u65f6\uff0c\u6211\u4eec\u5728\u4e0a\u4e00\u90e8\u5206\u4e2d\u521b\u5efa\u7684 TeamLead<\/code> \u7c7b\u5c06\u4e0d\u518d\u7f16\u8bd1\uff0cIntelliJ IDEA \u8fd8\u4f1a\u663e\u793a\u4e00\u6761\u9519\u8bef\u6d88\u606f\uff0c\u544a\u8bc9\u60a8\u7c7b\u4e0d\u80fd\u4ece Employee<\/code> \u7ee7\u627f\uff1a<\/p>\n
    \"\"<\/figure>\n
    \u60a8\u8fd8\u53ef\u4ee5\u5c06 final<\/code> \u4fee\u9970\u7b26\u6dfb\u52a0\u5230\u7c7b\u5c42\u6b21\u7ed3\u6784\u4e2d\u7684\u65b9\u6cd5\u3002 \u4f8b\u5982\uff0c\u5982\u679c\u60a8\u60f3\u9632\u6b62 getTitle()<\/code> getter \u88ab\u91cd\u5199\uff0c\u60a8\u53ef\u4ee5\u5c06\u5176\u8bbe\u4e3a final<\/code>\uff1a<\/p>\n
    \"\"<\/figure>\n
    \u5982\u679c\u8981\u9632\u6b62\u4e00\u4e2a\u7c7b\u88ab\u6269\u5c55\u5e76\u5c06\u7ee7\u627f\u9650\u5236\u4e3a\u51e0\u4e2a\u5df2\u77e5\u7684\u5b50\u7c7b\uff0c\u60a8\u8fd8\u53ef\u4ee5\u4f7f\u7528 sealed<\/code> \u4fee\u9970\u7b26\u548c permits<\/code> \u5b50\u53e5\uff1a<\/p>\n
    public sealed class Person permits Employee { } \/\/ no other classes than Employee can extend Person<\/pre>\n
    \u5982\u679c\u60a8\u60f3\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528 sealed<\/code> \u7c7b\uff0cIntelliJ IDEA \u5c06\u5e2e\u52a9\u60a8\u6839\u636e\u73b0\u6709\u7c7b\u5c42\u6b21\u7ed3\u6784\u751f\u6210 permits<\/code> \u5b50\u53e5\uff0c\u5e76\u76f8\u5e94\u5730\u66f4\u65b0\u5c42\u6b21\u7ed3\u6784\u4e2d\u7684\u6240\u6709\u7c7b\uff1a<\/p>\n
    \"\u4f7f\u7528<\/p>\n
    \u7ee7\u627f\u548c\u8bbf\u95ee\u7ea7\u522b\u4fee\u9970\u7b26<\/h2>\n
    Java \u6709\u591a\u4e2a\u8bbf\u95ee\u4fee\u9970\u7b26\uff0c\u53ef\u7528\u4e8e\u63a7\u5236\u7c7b\u3001\u6784\u9020\u51fd\u6570\u3001\u5c5e\u6027\u3001\u65b9\u6cd5\u548c\u5176\u4ed6\u6210\u5458\u7684\u4f5c\u7528\u57df\u3002<\/p>\n
    \u5bf9\u4e8e\u7c7b\uff0c\u6709\u4e24\u4e2a\u8bbf\u95ee\u7ea7\u522b\u4fee\u9970\u7b26\uff1apublic<\/code>\uff0c\u4f7f\u7c7b\u5728\u4efb\u4f55\u4f4d\u7f6e\u90fd\u53ef\u7528\uff1bpackage-private\uff0c\u4f7f\u7c7b\u4ec5\u5728\u5b9a\u4e49\u5b83\u7684\u8f6f\u4ef6\u5305\u4e2d\u53ef\u7528\u3002<\/p>\n
    \u5728\u7ee7\u627f\u548c\u7c7b\u5c42\u6b21\u7ed3\u6784\u4e0a\uff0c\u4efb\u4f55\u4f4d\u7f6e\u90fd\u53ef\u4ee5\u7ee7\u627f public<\/code> \u7c7b \u2013 \u60a8\u81ea\u5df1\u7684\u4ee3\u7801\u5e93\u7684\u6240\u6709\u8f6f\u4ef6\u5305\u548c\u6a21\u5757\u4e2d\uff0c\u4ee5\u53ca\u5f15\u7528\u4ee3\u7801\u4e2d\u3002 package-private \u7c7b\u53ea\u80fd\u5728\u540c\u4e00\u4e2a\u8f6f\u4ef6\u5305\u5185\u7ee7\u627f\uff0c\u5e76\u4e14\u5728\u6b64\u8f6f\u4ef6\u5305\u5916\u4e0d\u53ef\u7528\u3002 \u4e5f\u5c31\u662f\u8bf4\uff0c\u9664\u975e\u5b83\u4eec\u5177\u6709 final<\/code> \u4fee\u9970\u7b26\uff0c\u5426\u5219\u7ee7\u627f\u5b8c\u5168\u4e0d\u88ab\u5141\u8bb8\u3002<\/p>\n
    public class A { } \/\/ available everywhere, can be inherited from in any package\nclass B { } \/\/ available in the current package, can be inherited from in the current package<\/pre>\n
    \u5728\u6210\u5458\u7ea7\u522b\uff0c\u540c\u6837\u7684\u539f\u5219\u9002\u7528\uff1a\u60a8\u53ef\u4ee5\u4f7f\u7528 public<\/code> \u4fee\u9970\u7b26\u4f7f\u6210\u5458\u5728\u4efb\u4f55\u4f4d\u7f6e\u90fd\u53ef\u7528\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528 private<\/code> \u4f7f\u5176\u4ec5\u5728\u540c\u4e00\u4e2a\u7c7b\u4e2d\u53ef\u7528\u3002 \u60a8\u4e5f\u53ef\u4ee5\u4e0d\u4f7f\u7528\u4fee\u9970\u7b26\uff0c\u8fd9\u5c06\u4f7f\u6210\u5458\u5728\u6210\u5458\u6240\u5728\u8f6f\u4ef6\u5305\u4e2d\u53ef\u7528\u3002<\/p>\n
    \u6b64\u5916\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 protected<\/code> \u4fee\u9970\u7b26\u5141\u8bb8\u5b50\u7c7b\u8bbf\u95ee\u7279\u5b9a\u6210\u5458\u3002<\/p>\n
    public class C { \/\/ available everywhere, can be inherited from in any package\n  private int a; \/\/ available only within class C\n  public void b() { } \/\/ available everywhere\n  protected void c() \/\/ available only within class C and its subclasses in any package\n}<\/pre>\n
    \u4ee5\u4e0b\u662f\u8bbf\u95ee\u7ea7\u522b\u4ee5\u53ca\u5177\u4f53\u7c7b\u6210\u5458\u53ef\u7528\u4f4d\u7f6e\u7684\u5feb\u901f\u603b\u7ed3\uff1a<\/p>\n
    \n\n\n\n\n\n\n\n
    \u53ef\u7528\u4f4d\u7f6e\uff1a<\/strong><\/td>\n\u7c7b<\/strong><\/td>\n\u8f6f\u4ef6\u5305<\/strong><\/td>\n\u540c\u4e00\u8f6f\u4ef6\u5305\u7684\u5b50\u7c7b<\/strong><\/td>\n\u53e6\u4e00\u4e2a\u8f6f\u4ef6\u5305\u7684\u5b50\u7c7b<\/strong><\/td>\n\u4efb\u4f55\u5730\u65b9<\/strong><\/td>\n<\/tr>\n
    public<\/code><\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n<\/tr>\n
    protected<\/code><\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u00a0<\/td>\n<\/tr>\n
    package-private\uff08\u65e0\u4fee\u9970\u7b26\uff09<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u2714<\/td>\n\u00a0<\/td>\n\u00a0<\/td>\n<\/tr>\n
    private<\/code><\/td>\n\u2714<\/td>\n\u00a0<\/td>\n\u00a0<\/td>\n\u00a0<\/td>\n\u00a0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n
    \u56de\u5230\u6211\u4eec\u7684\u793a\u4f8b\uff0c\u60a8\u53ef\u4ee5\u770b\u5230 name<\/code> \u5b57\u6bb5\u4e3a private<\/code>\uff0c\u8fd9\u610f\u5473\u7740\u4efb\u4f55\u5b50\u7c7b\u90fd\u5fc5\u987b\u4f7f\u7528 getName()<\/code> getter \u8bbf\u95ee\u5b83\u7684\u503c\u3002 \u5982\u679c\u5c06\u5176\u8bbe\u4e3a protected<\/code>\uff0cname<\/code> \u5b57\u6bb5\u5c06\u5728 Person<\/code> \u7684\u6240\u6709\u5b50\u7c7b\u4e2d\u53ef\u7528\u3002<\/p>\n
    \u867d\u7136\u6240\u6709\u8bbf\u95ee\u7ea7\u522b\u4fee\u9970\u7b26\u90fd\u9002\u7528\u4e8e\u5b9a\u4e49\u7c7b\u53ca\u5176\u6210\u5458\u7684\u53ef\u7528\u4f5c\u7528\u57df\uff0c\u4f46 protected<\/code> \u4fee\u9970\u7b26\u5728\u901a\u8fc7\u7ee7\u627f\u521b\u5efa\u7c7b\u5c42\u6b21\u7ed3\u6784\u65f6\u975e\u5e38\u6709\u7528\u3002 \u8d85\u7c7b\u53ef\u4ee5\u5b9a\u4e49 protected \u5b57\u6bb5\u6216\u65b9\u6cd5\uff0c\u8fd9\u4e9b\u5b57\u6bb5\u6216\u65b9\u6cd5\u53ef\u4ee5\u7531\u5b50\u7c7b\u8bbf\u95ee\uff0c\u4f46\u4e0d\u80fd\u7531\u8fd9\u4e9b\u7c7b\u7684\u4f7f\u7528\u8005\u8bbf\u95ee\u3002<\/p>\n
    \u7ee7\u627f\u7684\u7f3a\u70b9<\/h2>\n
    \u7ee7\u627f\u6709\u5f88\u591a\u597d\u5904\uff0c\u4f8b\u5982\u91cd\u7528\u4ee3\u7801\u548c\u6269\u5c55\u73b0\u6709\u529f\u80fd\u3002 \u901a\u7528\u5c5e\u6027\u548c\u884c\u4e3a\u53ef\u4ee5\u5728\u8d85\u7c7b\u4e2d\u5b9a\u4e49\uff0c\u5b50\u7c7b\u53ef\u4ee5\u7ee7\u627f\u548c\u57fa\u4e8e\u5b83\u4eec\u6784\u5efa\uff0c\u5e76\u6dfb\u52a0\u6216\u91cd\u5199\u529f\u80fd\u3002<\/p>\n
    \u4f46\u4e5f\u6709\u4e00\u4e9b\u7f3a\u70b9\uff0c\u4f8b\u5982\u7c7b\u4e4b\u95f4\u7684\u7d27\u5bc6\u8026\u5408\u3002 \u5bf9\u8d85\u7c7b\u7684\u4efb\u4f55\u66f4\u6539\u90fd\u4f1a\u5f71\u54cd\u6240\u6709\u5b50\u7c7b\u3002 \u62e5\u6709\u8f83\u5927\u7684\u7c7b\u5c42\u6b21\u7ed3\u6784\u53ef\u80fd\u589e\u52a0\u590d\u6742\u7a0b\u5ea6\uff0c\u5c24\u5176\u662f\u5728\u6d89\u53ca\u591a\u4e2a\u7ee7\u627f\u7ea7\u522b\u7684\u5927\u578b\u9879\u76ee\u4e2d\u3002<\/p>\n
    \u603b\u7ed3<\/h2>\n
    \u5728\u8fd9\u7bc7\u535a\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u7ee7\u627f\u89c6\u4e3a Java \u7f16\u7a0b\u4e2d\u7684\u4e00\u4e2a\u57fa\u672c\u6982\u5ff5\u3002 \u7ee7\u627f\u5141\u8bb8\u901a\u8fc7\u4f7f\u7528 extends<\/code> \u5173\u952e\u5b57\u4ece\u73b0\u6709\u7c7b\uff08\u8d85\u7c7b\uff09\u6269\u5c55\u5c5e\u6027\u548c\u884c\u4e3a\u6765\u521b\u5efa\u65b0\u7c7b\uff08\u5b50\u7c7b\uff09\u3002 \u6211\u4eec\u8fd8\u8ba8\u8bba\u4e86\u62bd\u8c61\u7c7b\u548c\u63a5\u53e3\u3002<\/p>\n
    \u6211\u4eec\u8fd8\u63d0\u5230\u4e86 final<\/code> \u4fee\u9970\u7b26\uff0c\u5b83\u7528\u4e8e\u9632\u6b62\u7c7b\u7684\u7ee7\u627f\u6216\u9632\u6b62\u91cd\u5199\u7279\u5b9a\u7c7b\u6210\u5458\u3002 \u5c06\u5176\u4e0e\u8bbf\u95ee\u7ea7\u522b\u4fee\u9970\u7b26\u76f8\u7ed3\u5408\uff0c\u60a8\u53ef\u4ee5\u5b9a\u4e49\u53ef\u4ee5\u7ee7\u627f\u7c7b\u7684\u4f4d\u7f6e\u4ee5\u53ca\u7c7b\u6210\u5458\u7684\u53ef\u7528\u4f4d\u7f6e\u3002<\/p>\n
    \u5728 <\/strong>IntelliJ IDEA<\/strong><\/a> \u4e2d\u5c1d\u8bd5\u4e00\u4e0b<\/strong>\uff01<\/p>\n\n\n
    <\/p>\n\n\n\n
    \u672c\u535a\u6587\u82f1\u6587\u539f\u4f5c\u8005\uff1a<\/p>\n\n\n    
    \n        
    \n            
    \n                
    \n                    \"\"\n                <\/div>\n                
    \n                                                        <\/div>\n            <\/div>\n        <\/div>\n    <\/div>\n","protected":false},"author":1297,"featured_media":434328,"comment_status":"closed","ping_status":"closed","template":"","categories":[4759,5088],"tags":[40,155,743],"cross-post-tag":[],"acf":[],"_links":{"self":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/idea\/461288"}],"collection":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/idea"}],"about":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/types\/idea"}],"author":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/users\/1297"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/comments?post=461288"}],"version-history":[{"count":8,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/idea\/461288\/revisions"}],"predecessor-version":[{"id":461349,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/idea\/461288\/revisions\/461349"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/media\/434328"}],"wp:attachment":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/media?parent=461288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/categories?post=461288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/tags?post=461288"},{"taxonomy":"cross-post-tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/cross-post-tag?post=461288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}