问题描述
// This class is a friend of most classes, to be able to access// private fieldsclass VMStructs {public: // The last entry is identified over in the serviceability agent by // the fact that it has a NULL fieldName static VMStructEntry localHotSpotVMStructs[]; // The last entry is identified over in the serviceability agent by // the fact that it has a NULL typeName static VMTypeEntry localHotSpotVMTypes[]; // Table of integer constants required by the serviceability agent. // The last entry is identified over in the serviceability agent by // the fact that it has a NULL typeName static VMIntConstantEntry localHotSpotVMIntConstants[]; // Table of long constants required by the serviceability agent. // The last entry is identified over in the serviceability agent by // the fact that it has a NULL typeName static VMLongConstantEntry localHotSpotVMLongConstants[]; // This is used to run any checking code necessary for validation of // the data structure (debug build only) static void init();#ifndef PRODUCT // Execute unit tests static void test();#endifprivate: // Look up a type in localHotSpotVMTypes using strcmp() (debug build only). // Returns 1 if found, 0 if not. // debug_only(static int findType(const char* typeName);) static int findType(const char* typeName);};
其中我看不懂的地方就是
static VMStructEntry localHotSpotVMStructs[];
static VMTypeEntry localHotSpotVMTypes[];...
这样的定义究竟是什么呢？看着像函数，但是却又用的是数组，它究竟是什么呢？其中，localHotSpotVMStructs[] 定义如下// These initializers are allowed to access private fields in classes// as long as class VMStructs is a friendVMStructEntry VMStructs::localHotSpotVMStructs[] = { VM_STRUCTS(GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_STATIC_VM_STRUCT_ENTRY, GENERATE_UNCHECKED_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONPRODUCT_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C1_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C2_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C1_UNCHECKED_STATIC_VM_STRUCT_ENTRY, GENERATE_C2_UNCHECKED_STATIC_VM_STRUCT_ENTRY)#if INCLUDE_ALL_GCS VM_STRUCTS_PARALLELGC(GENERATE_NONSTATIC_VM_STRUCT_ENTRY,GENERATE_STATIC_VM_STRUCT_ENTRY) VM_STRUCTS_CMS(GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_STATIC_VM_STRUCT_ENTRY) VM_STRUCTS_G1(GENERATE_NONSTATIC_VM_STRUCT_ENTRY,GENERATE_STATIC_VM_STRUCT_ENTRY)#endif // INCLUDE_ALL_GCS#if INCLUDE_TRACE VM_STRUCTS_TRACE(GENERATE_NONSTATIC_VM_STRUCT_ENTRY,GENERATE_STATIC_VM_STRUCT_ENTRY)#endif VM_STRUCTS_CPU(GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_STATIC_VM_STRUCT_ENTRY, GENERATE_UNCHECKED_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONPRODUCT_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C2_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C1_UNCHECKED_STATIC_VM_STRUCT_ENTRY, GENERATE_C2_UNCHECKED_STATIC_VM_STRUCT_ENTRY) VM_STRUCTS_OS_CPU(GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_STATIC_VM_STRUCT_ENTRY, GENERATE_UNCHECKED_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_NONPRODUCT_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C2_NONSTATIC_VM_STRUCT_ENTRY, GENERATE_C1_UNCHECKED_STATIC_VM_STRUCT_ENTRY, GENERATE_C2_UNCHECKED_STATIC_VM_STRUCT_ENTRY) GENERATE_VM_STRUCT_LAST_ENTRY()};localHotSpotVMTypes[]的定义如下
VMTypeEntry VMStructs::localHotSpotVMTypes[] = { VM_TYPES(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_OOP_VM_TYPE_ENTRY, GENERATE_INTEGER_VM_TYPE_ENTRY, GENERATE_UNSIGNED_INTEGER_VM_TYPE_ENTRY, GENERATE_C1_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_C2_VM_TYPE_ENTRY, GENERATE_C2_TOPLEVEL_VM_TYPE_ENTRY)#if INCLUDE_ALL_GCS VM_TYPES_PARALLELGC(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY) VM_TYPES_CMS(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY) VM_TYPES_PARNEW(GENERATE_VM_TYPE_ENTRY) VM_TYPES_G1(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY)#endif // INCLUDE_ALL_GCS#if INCLUDE_TRACE VM_TYPES_TRACE(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY)#endif VM_TYPES_CPU(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_OOP_VM_TYPE_ENTRY, GENERATE_INTEGER_VM_TYPE_ENTRY, GENERATE_UNSIGNED_INTEGER_VM_TYPE_ENTRY, GENERATE_C1_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_C2_VM_TYPE_ENTRY, GENERATE_C2_TOPLEVEL_VM_TYPE_ENTRY) VM_TYPES_OS_CPU(GENERATE_VM_TYPE_ENTRY, GENERATE_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_OOP_VM_TYPE_ENTRY, GENERATE_INTEGER_VM_TYPE_ENTRY, GENERATE_UNSIGNED_INTEGER_VM_TYPE_ENTRY, GENERATE_C1_TOPLEVEL_VM_TYPE_ENTRY, GENERATE_C2_VM_TYPE_ENTRY, GENERATE_C2_TOPLEVEL_VM_TYPE_ENTRY) GENERATE_VM_TYPE_LAST_ENTRY()};
代码来自jdk8
问题解答
回答1：static VMStructEntry localHotSpotVMStructs[]; | | | | | | | | | | | | 静态 类型 变量名 数组
去看看 VMStructEntry 的定义。不论如何，这就是一个数组，是一个 VMStructEntry 类型的数组。
