{"id":152867,"date":"2020-09-07T22:23:49","date_gmt":"2020-09-07T14:23:49","guid":{"rendered":"http:\/\/4563.org\/?p=152867"},"modified":"2020-09-07T22:23:49","modified_gmt":"2020-09-07T14:23:49","slug":"%e5%85%b3%e4%ba%8einside-the-java-virtual-machine-chapter-7-the-lifetime-of-a-type-initialization%e7%9a%84%e7%96%91%e9%97%ae","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=152867","title":{"rendered":"\u5173\u4e8e\u201cInside the Java Virtual Machine – Chapter 7 The Lifetime of a Type – Initialization\u201d\u7684\u7591\u95ee"},"content":{"rendered":"
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\u5173\u4e8e\u201cInside the Java Virtual Machine – Chapter 7 The Lifetime of a Type – Initialization\u201d\u7684\u7591\u95ee <\/h1>\n

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\u8cc7\u6df1\u5927\u4f6c : JasonLaw <\/span> <\/i> 0<\/span> <\/div>\n
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\u5728Inside the Java Virtual Machine – Chapter 7 The Lifetime of a Type – Initialization\u4e2d\uff0c\u6709\u8fd9\u4e48\u4e00\u6bb5\uff1a<\/p>\n

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A use of a non-constant static field is an active use of only the class or interface that actually declares the field. For example, a field declared in a class may be referred to via a subclass. A field declared in an interface may be referred to via a subinterface or class that implements the interface. These are passive uses of the subclass, subinterface, or class that implements the interface–uses that won’t trigger their initialization. They are an active use only of the class or interface in which the field is actually declared. Here’s an example that illustrates this principle:<\/p>\n

\/\/ On CD-ROM in file classlife\/ex2\/NewParent.java class NewParent {      static int hoursOfSleep = (int) (Math.random() * 3.0);      static {         System.out.println(\"NewParent was initialized.\");     } }  \/\/ On CD-ROM in file classlife\/ex2\/NewbornBaby.java class NewbornBaby extends NewParent {      static int hoursOfCrying = 6 + (int) (Math.random() * 2.0);      static {         System.out.println(\"NewbornBaby was initialized.\");     } }  \/\/ On CD-ROM in file classlife\/ex2\/Example2.java class Example2 {      \/\/ Invoking main() is an active use of Example2     public static void main(String[] args) {          \/\/ Using hoursOfSleep is an active use of NewParent,         \/\/ but a passive use of NewbornBaby         int hours = NewbornBaby.hoursOfSleep;         System.out.println(hours);     }      static {         System.out.println(\"Example2 was initialized.\");     } } <\/code><\/pre>\n<\/blockquote>\n
\u7136\u540e\u5b83\u8bf4\uff1a<\/p>\n
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In the above example, executing main() of Example2 causes only Example2 and NewParent to be initialized. NewbornBaby is not initialized and need not be loaded.<\/p>\n<\/blockquote>\n
\u6211\u660e\u767d\u201cNewbornBaby is not initialized\u201d\uff0c\u4f46\u662f\u4e3a\u4ec0\u4e48\u201cNewbornBaby need not be loaded\u201d\u5462\uff1f\u5982\u679c NewbornBaby \u90fd\u6ca1\u6709\u88ab loaded\uff0c\u90a3\u4e48 JVM \u600e\u4e48\u53ef\u80fd\u77e5\u9053 hoursOfSleep \u662f\u6765\u6e90\u4e8e NewParent \u7684\u5462\uff1f<\/p>\n
java -verbose:class Example2<\/code>\u7684\u8f93\u51fa\u7247\u6bb5\u5982\u4e0b\uff1a<\/p>\n
[Loaded Example2 from file:\/Users\/jason\/trivial\/] [Loaded sun.launcher.LauncherHelper$FXHelper from \/Library\/Java\/JavaVirtualMachines\/jdk1.8.0_181.jdk\/Contents\/Home\/jre\/lib\/rt.jar] [Loaded java.lang.Class$MethodArray from \/Library\/Java\/JavaVirtualMachines\/jdk1.8.0_181.jdk\/Contents\/Home\/jre\/lib\/rt.jar] [Loaded java.lang.Void from \/Library\/Java\/JavaVirtualMachines\/jdk1.8.0_181.jdk\/Contents\/Home\/jre\/lib\/rt.jar] Example2 was initialized. [Loaded NewParent from file:\/Users\/jason\/trivial\/] [Loaded NewbornBaby from file:\/Users\/jason\/trivial\/] [Loaded java.lang.Math$RandomNumberGeneratorHolder from \/Library\/Java\/JavaVirtualMachines\/jdk1.8.0_181.jdk\/Contents\/Home\/jre\/lib\/rt.jar] [Loaded java.util.Random from \/Library\/Java\/JavaVirtualMachines\/jdk1.8.0_181.jdk\/Contents\/Home\/jre\/lib\/rt.jar] NewParent was initialized. 1 <\/code><\/pre>\n
\u867d\u7136\u7ed3\u679c\u663e\u793a NewbornBaby \u88ab loaded \u4e86\uff0c\u4f46\u662f\u4e3a\u4ec0\u4e48 NewParent \u5148\u4e8e NewbornBaby \u88ab loaded \u5462\uff1f<\/p>\n<\/p><\/div>\n
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 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (22<\/span>)        <\/div>\n
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                                                                 \u5c31\u7b97\u4ece\u4e0d\u521b\u5efa\u7c7b\u7684\u5b9e\u4f8b,\u7c7b\u5b57\u6bb5\u4e5f\u548c\u7c7b\u5173\u8054,\u7c7b\u5b57\u6bb5\u4f1a\u5728\u8c03\u7528\u6784\u9020\u65b9\u6cd5\u524d\u521d\u59cb\u5316,javac \u4f1a\u4e3a\u6bcf\u4e2a\u7c7b\u81ea\u52a8\u751f\u6210\u4e00\u4e2a\u7c7b\u521d\u59cb\u5316\u65b9\u6cd5,\u7c7b\u5b57\u6bb5\u4f1a\u5728\u8fd9\u4e2a\u65b9\u6cd5\u91cc\u521d\u59cb\u5316,\u7c7b\u7684\u521d\u59cb\u5316\u662f\u5185\u90e8\u65b9\u6cd5,\u5bf9\u7a0b\u5e8f\u5458\u4e0d\u53ef\u89c1. <\/p>\n
    \u5982\u679c\u6211\u6ca1\u8bb0\u9519,\u53ef\u4ee5\u7528 javap \u770b\u770b\u521d\u59cb\u5316\u65b9\u6cd5, \u4f60\u7ed9\u7684\u8fd9\u4e2a\u4f8b\u5b50\u5168\u662f static,\u76f4\u63a5\u770b\u6df1\u5165 static \u65b9\u9762\u7684\u77e5\u8bc6\u5c31\u597d\u4e86                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @ik2h #1 \u4f60\u8bf4\u7684\u90fd\u662f\u5173\u4e8e initialization \u7684\uff0c\u800c\u6211\u7684\u95ee\u9898\u662f\u5173\u4e8e loading \u7684\u3002<\/p>\n
    \u987a\u4fbf\u8bf4\u4e00\u4e0b\uff0c\u201cjavac \u4f1a\u4e3a\u6bcf\u4e2a\u7c7b\u81ea\u52a8\u751f\u6210\u4e00\u4e2a\u7c7b\u521d\u59cb\u5316\u65b9\u6cd5\u201d\u4e0d\u662f\u5b8c\u5168\u6b63\u786e\u7684\u3002<\/p>\n
    \u5173\u4e8e\u4ec0\u4e48\u60c5\u51b5\u4f1a\u4ea7\u751f()\u65b9\u6cd5\uff0chttps:\/\/www.artima.com\/insidejvm\/ed2\/lifetype4.html \u4e2d\u63cf\u8ff0\u4e86\u5f88\u6e05\u695a\uff0c\u4ee5\u4e0b\u662f\u4e00\u4e9b\u7247\u6bb5\uff1a<\/p>\n
    Not all classes will necessarily have a () method in their class file. If a class declares no class variables or static initializers, it won’t have a () method. If a class declares class variables, but doesn’t explicitly initialize them with class variable initializers or static initializers, it won’t have a () method. If a class contains only class variable initializers for static final variables, and those class variable initializers use compile-time constant expressions, that class won’t have a () method. Only those classes that actually require Java code to be executed to initialize class variables to proper initial values will have a class initialization method.<\/p>\n
    Interfaces may also be awarded a () method in the class file. All fields declared in an interface are implicitly public, static, and final and must be initialized with a field initializer. If an interface has any field initializers that don’t resolve at compile-time to a constant, that interface will have a () method.                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @JasonLaw https:\/\/docs.oracle.com\/javase\/specs\/jls\/se7\/html\/jls-12.html <\/p>\n
    A reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it, even though it might be referred to through the name of a subclass, a subinterface, or a class that implements an interface.                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : Jooooooooo <\/span>  <\/div>\n
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                                                                 load \u5b50\u7c7b\u80af\u5b9a\u8981\u5148 load \u7236\u7c7b\u5427                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @ik2h #3 \u5148\u629b\u5f00\u5176\u4ed6\u7684\uff0c\u5355\u7eaf\u8ba8\u8bba 3 \u6240\u5f15\u7528\u7684\u5185\u5bb9\u3002<\/p>\n
    \u201cA reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it\u201d\u4e0d\u4e00\u5b9a\u6b63\u786e\u3002\u4e3b\u9898\u6b63\u6587\u4e2d\u7684\u5916\u94fe\uff08\u56e0\u4e3a\u63d0\u793a\u56de\u590d\u4e0d\u80fd\u5305\u542b\u5916\u94fe\uff0c\u6240\u4ee5\u53ea\u80fd\u8fd9\u4e48\u5f04\uff09\u8bf4\u4e86\u201cA use of a field that is both static and final, and initialized by a compile-time constant expression, is not an active use of the type that declares the field.\u201d\uff0c\u5176\u4e2d\u7684 Example3 \u4e5f\u6f14\u793a\u4e86\uff08\u867d\u7136 Example3 \u4e2d\u5f15\u7528\u4e86 Angry.greeting \u548c Dog.greeting\uff0c\u4f46\u662f Angry \u548c Dog \u90fd\u6ca1\u6709\u88ab\u521d\u59cb\u5316\uff09\u3002<\/p>\n
    \u8fd8\u662f\u6211\u54ea\u91cc\u7406\u89e3\u9519\u4e86\uff1f                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @JasonLaw \u7f16\u8bd1\u65f6\u5e38\u91cf                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @JasonLaw \u8fd9\u65b9\u9762\u662f\u5173\u4e8e\u7c7b\u7684\u4e3b\u52a8\u5f15\u7528\u548c\u88ab\u52a8\u5f15\u7528, \u6211\u8bb0\u5f97 final static \u5728 java \u7f16\u7a0b\u601d\u60f3\u91cc\u9762\u4e5f\u6709\u63d0\u53ca\u8fd9\u65b9\u9762\u7684\u5185\u5bb9                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @ik2h #6 \u662f\u7684\uff0c\u6240\u4ee5\u201cA reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it\u201d\u4e0d\u4e00\u5b9a\u6b63\u786e\u5440\u3002\u96be\u9053\u201ca field that is both static and final, and initialized by a compile-time constant expression\u201d\u4e0d\u662f\u4e00\u4e2a\u201cstatic field\u201d\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @Jooooooooo #4 \u4f60\u53ef\u4ee5\u770b\u770b\u7b2c\u4e00\u6761\u9644\u8a00\u3002\u65e2\u7136\u5b50\u7c7b\u6ca1\u6709\u5148\u88ab loaded\uff0cJVM \u662f\u600e\u4e48\u77e5\u9053\u5b50\u7c7b\u7684\u7236\u7c7b\u662f\u4ec0\u4e48\u5462\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @JasonLaw \u300a\u6df1\u5165\u7406\u89e3 Java \u865a\u62df\u673a\u300b 7.2 \u6709\u6bd4\u8f83\u8be6\u7ec6\u7684\u89e3\u91ca,\u7f16\u8bd1\u65f6\u5e38\u91cf\u5728\u7f16\u8bd1\u9636\u6bb5\u4f1a\u5b58\u5165\u8c03\u7528\u7c7b\u7684\u5e38\u91cf\u6c60\u4e2d\uff0c\u672c\u8d28\u4e0a\u5e76\u6ca1\u6709\u76f4\u63a5\u5f15\u7528\u5230\u5b9a\u4e49\u5e38\u91cf\u7684\u7c7b\uff0c\u56e0\u6b64\u4e0d\u4f1a\u89e6\u53d1\u5b9a\u4e49\u5e38\u91cf\u7684\u7c7b\u7684\u521d\u59cb\u5316\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @JasonLaw \u53ef\u4ee5\u6253\u5f00 .class \u6587\u4ef6\u770b\u4e00\u4e0b main \u65b9\u6cd5\u7684\u5b57\u8282\u7801\u662f\u600e\u4e48\u6837\u7684. \u7279\u522b\u662f\u8fd9\u4e00\u53e5 int hours = NewbornBaby.hoursOfSleep; \u5f15\u7528\u7684\u5e38\u91cf\u6c60\u662f\u600e\u4e48\u5bf9\u5e94\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @Jooooooooo #11 “int hours = NewbornBaby.hoursOfSleep;”\u5bf9\u5e94\u7684\u5b57\u8282\u7801\u4e3a”getstatic #2 \u548c istore_1″\u3002\u5728 constant pool \u4e2d\uff0cindex \u4e3a 2 \u7684 entry \u662f\u4e00\u4e2a CONSTANT_Fieldref_info\uff0c\u901a\u8fc7 CONSTANT_Fieldref_info \u4e2d\u7684 class_index \u6700\u540e\u4f1a\u5f97\u5230 NewbornBaby\uff0c\u901a\u8fc7 CONSTANT_Fieldref_info \u4e2d\u7684 name_and_type_index\uff0c\u6700\u540e\u4f1a\u5f97\u5230\u4e00\u4e2a CONSTANT_NameAndType_info\uff0c\u901a\u8fc7 CONSTANT_NameAndType_info \u4e2d\u7684 name_index \u6700\u540e\u4f1a\u5f97\u5230 hoursOfSleep\uff0c\u901a\u8fc7 CONSTANT_NameAndType_info \u4e2d\u7684 descriptor_index \u6700\u540e\u4f1a\u5f97\u5230 I \u3002<\/p>\n
    \u7136\u540e\u5462\uff1f\u4e3a\u4ec0\u4e48\u7236\u7c7b\u5148\u4e8e\u5b50\u7c7b\u88ab loaded \uff1f\u5b50\u7c7b\u6ca1\u6709\u5148\u88ab loaded\uff0cJVM \u662f\u600e\u4e48\u77e5\u9053\u5b50\u7c7b\u7684\u7236\u7c7b\u662f\u4ec0\u4e48\u5462\uff1f                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @ik2h #10 \u6211\u611f\u89c9\uff0c\u6211\u4eec\u6839\u672c\u4e0d\u662f\u5728\u8ba8\u8bba\u4e00\u4e2a\u4e1c\u897f\uff0c\u76f8\u5173\u7684\u56de\u590d\u4e5f\u6ca1\u6709\u4ec0\u4e48\u4e0a\u4e0b\u6587\u5173\u7cfb\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : mind3x <\/span>  <\/div>\n
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                                                                 @JasonLaw 
    > \u201cA reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it\u201d\u4e0d\u4e00\u5b9a\u6b63\u786e\u3002<\/p>\n
    @ik2h \u5728 #3 \u4e2d\u5f15\u7528\u7684\u662f JLS\uff0c\u867d\u7136\u7248\u672c\u65e7\u4e86\u70b9\uff0c\u597d\u6b79\u4e5f\u662f\u6b63\u5b97\u5b98\u65b9\u7684\u8bed\u8a00 specification\uff0c\u4f55\u6765\u7684\u201c\u4e0d\u4e00\u5b9a\u6b63\u786e\u201d\uff1f\u4f60\u5173\u5fc3\u7684\u95ee\u9898\u672c\u6765\u5c31\u5e94\u8be5\u4ece JLS \u548c JVM Spec \u91cc\u9762\u5bfb\u627e\u7b54\u6848\u3002<\/p>\n
    \u81f3\u4e8e\u4f60\u7684\u6838\u5fc3\u95ee\u9898 NewParent \u4e3a\u4ec0\u4e48\u5148\u4e8e NewbornBaby \u88ab load\uff0c\u539f\u56e0\u5f88\u7b80\u5355\uff1a\u7c7b\u52a0\u8f7d\u662f\u4e00\u8fb9\u89e3\u6790\u4e00\u8fb9\u9012\u5f52\u7684\u2014\u2014\u8fd9\u91cc\u7684\u987a\u5e8f\u662f \u5f00\u59cb\u52a0\u8f7d NewbornBaby -> \u89e3\u6790 NewbornBaby -> \u53d1\u73b0\u7236\u7c7b NewParent -> (\u9012\u5f52) \u5f00\u59cb\u52a0\u8f7d NewParent -> … -> \u52a0\u8f7d NewParent \u7ed3\u675f -> \u7ee7\u7eed\u52a0\u8f7d NewbornBaby -> \u52a0\u8f7d NewParent \u7ed3\u675f\u3002\u4f60\u770b\u5230\u7684 log \u53ea\u662f\u6253\u4e86 load \u7ed3\u675f\u800c\u5df2\u3002<\/p>\n
    JVM Spec (1.7 \u7248) 5.3: https:\/\/docs.oracle.com\/javase\/specs\/jvms\/se7\/html\/jvms-5.html#jvms-5.3<\/p>\n
    > A subtlety here is that recursive class loading to load superclasses is performed as part of resolution (\u00a75.3.5, step 3). Therefore, a ClassNotFoundException that results from a class loader failing to load a superclass must be wrapped in a NoClassDefFoundError.                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @mind3x #14<\/p>\n
    typo: “\u7ee7\u7eed\u52a0\u8f7d NewbornBaby -> \u52a0\u8f7d NewParent \u7ed3\u675f” \u5e94\u4e3a “\u7ee7\u7eed\u52a0\u8f7d NewbornBaby -> \u52a0\u8f7d NewbornBaby” \u7ed3\u675f\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : JasonLaw <\/span>  <\/div>\n
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                                                                 @Jooooooooo #4 \u5b50\u7c7b\u8fd8\u662f\u8981\u5148\u88ab loaded \u7684\uff0c\u53ea\u662f\u7236\u7c7b\u5148\u88ab loaded \u5b8c\u6210\uff0c\u5177\u4f53\u53ef\u4ee5\u770b\u770b\u7b2c 2 \u6761\u9644\u8a00\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : JasonLaw <\/span>  <\/div>\n
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                                                                 @mind3x #14 
    @mind3x #15 <\/p>\n
    \u201c\u4e3a\u4ec0\u4e48 NewParent \u5148\u4e8e NewbornBaby \u88ab loaded\u201d\u662f\u6211\u81ea\u5df1\u6ca1\u6709\u8ba4\u771f\u770b\u6e05\u695a\u7684\u95ee\u9898\uff0c\u6211\u7684\u6838\u5fc3\u95ee\u9898\u5e76\u4e0d\u662f\u8fd9\u4e2a\uff0c\u6211\u7684\u6838\u5fc3\u95ee\u9898\u662f\u201c\u4e3a\u4ec0\u4e48 NewbornBaby need not be loaded\u201d\u3002\u5173\u4e8e\u8fd9\u4e2a\u95ee\u9898\uff0cHolger \u5728 Stack Overflow \u4e0a\u9762\u56de\u7b54\u6211\u4e86\uff0c\u5177\u4f53\u53ef\u4ee5\u770b\u770b\u7b2c 2 \u6761\u9644\u8a00\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : JasonLaw <\/span>  <\/div>\n
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                                                                 @mind3x #14 \u4f60\u8bf4\u201cA reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it\u201d\u6765\u6e90\u4e8e\u5b98\u65b9\u6587\u6863\uff0c\u4e00\u5b9a\u662f\u6b63\u786e\u7684\u3002\u96be\u9053\u201ca field that is both static and final, and initialized by a compile-time constant expression\u201d\u4e0d\u662f\u4e00\u4e2a\u201cstatic field\u201d\uff1f<\/p>\n
    \u6bd4\u5982\u6211\u5c06 NewbornBaby \u6539\u4e3a\u4e0b\u9762\u8fd9\u6837\uff1a<\/p>\n
    “`
    class NewbornBaby extends NewParent {<\/p>\n
     static int hoursOfCrying = 6 + (int) (Math.random() * 2.0);<\/p>\n
     static final int hoursOfSleep = 6; \/\/ a field that is both static and final, and initialized by a compile-time constant expression<\/p>\n
     static {
     System.out.println(“NewbornBaby was initialized.”);
     }
    }
    “`<\/p>\n
    \u8fd0\u884c java -verbose Example2\uff0c\u53ef\u4ee5\u770b\u51fa NewbornBaby \u88ab\u6ca1\u6709\u88ab loaded \u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : Jooooooooo <\/span>  <\/div>\n
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                                                                 @JasonLaw \u4f60\u6700\u65e9\u770b\u7684\u90a3\u7bc7\u662f\u6587\u7ae0\u662f\u9519\u7684\u86ee\u5751\u7684.                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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                                                                 @Jooooooooo #19 \u5176\u5b9e Inside the Java Virtual Machine \u8fd8\u662f\u5f88\u597d\u7684\uff0c\u73b0\u5728\u770b\u4e86 Chapter 5-7\uff0c\u53ea\u53d1\u73b0\u4e86\u8fd9\u4e00\u4e2a\u9519\u8bef\uff0c\u5176\u4ed6\u7684\u90fd\u89e3\u91ca\u5f97\u5f88\u597d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : mind3x <\/span>  <\/div>\n
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                                                                 @JasonLaw <\/p>\n
    #17 “NewbornBaby need not be loaded” \u8fd9\u53e5\u8bdd\u662f\u9519\u7684\uff0c\u5f88\u591a\u4e66\u90fd\u6709\u9519\uff0c\u8fd9\u4e2a\u6b63\u5e38\u3002\u4ee5 JLS, JVMS \u4e3a\u51c6\u3002<\/p>\n
    #18 \u6ca1\u9519\uff0c”A reference to a static field (\u00a78.3.1.1) causes initialization of only the class or interface that actually declares it” \u662f\u6b63\u786e\u7684\u3002\u8fd9\u91cc\u7684\u91cd\u70b9\u662f “reference” (\u6572\u9ed1\u677f)\u3002\u4f60\u52a0\u4e86 final\uff0c\u8fd9\u4e2a\u503c\u5c31\u662f\u4e2a\u5e38\u91cf\uff0c\u76f4\u63a5\u5728\u7f16\u8bd1\u65f6\u653e\u8fdb Example2 \u7684\u5e38\u91cf\u6c60\u4e86\uff0c\u800c\u4e0d\u662f\u5f15\u7528 NewbornBaby \u3002\u4f60\u53ef\u4ee5\u770b\u5b57\u8282\u7801\u7684\u533a\u522b\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : JasonLaw <\/span>  <\/div>\n
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                                                                 @mind3x \u5982\u679c\u5bf9\u201ca reference to a static field\u201d\u662f\u8fd9\u6837\u7406\u89e3\u7684\u8bdd\uff0c\u90a3\u53e5\u8bdd\u7684\u786e\u662f\u5bf9\u7684\u3002\u6211\u7684\u5173\u6ce8\u70b9\u662f source code\uff0c\u800c\u4f60\u7684\u662f compiled code \u3002\u603b\u4e4b\u8c22\u8c22\u4f60\u7684\u56de\u590d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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    \u5173\u4e8e\u201cInside the Jav…<\/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\/152867"}],"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=152867"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/152867\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=152867"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=152867"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=152867"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}