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/OpenJDK 21

Enum Class AccessFlag

java.lang.Object
java.lang.Enum<AccessFlag>
java.lang.reflect.AccessFlag
All Implemented Interfaces:
Serializable, Comparable<AccessFlag>, Constable 
public enum AccessFlag extends Enum<AccessFlag>
Represents a JVM access or module-related flag on a runtime member, such as a class, field, or method.

JVM access and module-related flags are related to, but distinct from Java language modifiers. Some modifiers and access flags have a one-to-one correspondence, such as public. In other cases, some language-level modifiers do not have an access flag, such as sealed (JVMS 4.7.31) and some access flags have no corresponding modifier, such as synthetic.

The values for the constants representing the access and module flags are taken from sections of The Java Virtual Machine Specification including 4.1 (class access and property modifiers), 4.5 (field access and property flags), 4.6 (method access and property flags), 4.7.6 (nested class access and property flags), 4.7.24 (method parameters), and 4.7.25 (module flags and requires, exports, and opens flags).

The mask values for the different access flags are not distinct. Flags are defined for different kinds of JVM structures and the same bit position has different meanings in different contexts. For example, 0x0000_0040 indicates a volatile field but a bridge method; 0x0000_0080 indicates a transient field but a variable arity (varargs) method.

API Note:
The JVM class file format has a new version defined for each new feature release. A new class file version may define new access flags or retire old ones. AccessFlag is intended to model the set of access flags across class file format versions. The range of versions an access flag is recognized is not explicitly indicated in this API. See the current The Java Virtual Machine Specification for details. Unless otherwise indicated, access flags can be assumed to be recognized in the current version.
Implementation Requirements:
The access flag constants are ordered by non-decreasing mask value; that is the mask value of a constant is greater than or equal to the mask value of an immediate neighbor to its (syntactic) left. If new constants are added, this property will be maintained. That implies new constants will not necessarily be added at the end of the existing list.
Since:
20
See Also:

Nested Class Summary

Modifier and Type Class Description
static enum  AccessFlag.Location
A location within a class file where flags can be applied.

Nested classes/interfaces declared in class java.lang.Enum

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constant Description
ABSTRACT
The access flag ACC_ABSTRACT, corresponding to the source modifier abstract, with a mask value of 0x0400.
ANNOTATION
The access flag ACC_ANNOTATION with a mask value of 0x2000.
BRIDGE
The access flag ACC_BRIDGE with a mask value of 0x0040
ENUM
The access flag ACC_ENUM with a mask value of 0x4000.
FINAL
The access flag ACC_FINAL, corresponding to the source modifier final, with a mask value of 0x0010.
INTERFACE
The access flag ACC_INTERFACE with a mask value of 0x0200.
MANDATED
The access flag ACC_MANDATED with a mask value of 0x8000.
MODULE
The access flag ACC_MODULE with a mask value of 0x8000.
NATIVE
The access flag ACC_NATIVE, corresponding to the source modifier native, with a mask value of 0x0100.
OPEN
The module flag ACC_OPEN with a mask value of 0x0020.
PRIVATE
The access flag ACC_PRIVATE, corresponding to the source modifier private, with a mask value of 0x0002.
PROTECTED
The access flag ACC_PROTECTED, corresponding to the source modifier protected, with a mask value of 0x0004.
PUBLIC
The access flag ACC_PUBLIC, corresponding to the source modifier public, with a mask value of 0x0001.
STATIC
The access flag ACC_STATIC, corresponding to the source modifier static, with a mask value of 0x0008.
STATIC_PHASE
The module requires flag ACC_STATIC_PHASE with a mask value of 0x0040.
STRICT
The access flag ACC_STRICT, corresponding to the source modifier strictfp, with a mask value of 0x0800.
SUPER
The access flag ACC_SUPER with a mask value of 0x0020.
SYNCHRONIZED
The access flag ACC_SYNCHRONIZED, corresponding to the source modifier synchronized, with a mask value of 0x0020.
SYNTHETIC
The access flag ACC_SYNTHETIC with a mask value of 0x1000.
TRANSIENT
The access flag ACC_TRANSIENT, corresponding to the source modifier transient, with a mask value of 0x0080.
TRANSITIVE
The module requires flag ACC_TRANSITIVE with a mask value of 0x0020.
VARARGS
The access flag ACC_VARARGS with a mask value of 0x0080.
VOLATILE
The access flag ACC_VOLATILE, corresponding to the source modifier volatile, with a mask value of 0x0040.

Method Summary

Modifier and Type Method Description
Set<AccessFlag.Location> locations()
Returns kinds of constructs the flag can be applied to in the latest class file format version.
Set<AccessFlag.Location> locations(ClassFileFormatVersion cffv)
Returns kinds of constructs the flag can be applied to in the given class file format version.
int mask()
Returns the corresponding integer mask for the access flag.
static Set<AccessFlag> maskToAccessFlags(int mask, AccessFlag.Location location)
Returns an unmodifiable set of access flags for the given mask value appropriate for the location in question.
boolean sourceModifier()
Returns whether or not the flag has a directly corresponding modifier in the Java programming language.
static AccessFlag valueOf(String name)
Returns the enum constant of this class with the specified name.
static AccessFlag[] values()
Returns an array containing the constants of this enum class, in the order they are declared.

Methods declared in class java.lang.Enum

clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods declared in class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details

PUBLIC

public static final AccessFlag PUBLIC
The access flag ACC_PUBLIC, corresponding to the source modifier public, with a mask value of 0x0001.

PRIVATE

public static final AccessFlag PRIVATE
The access flag ACC_PRIVATE, corresponding to the source modifier private, with a mask value of 0x0002.

PROTECTED

public static final AccessFlag PROTECTED
The access flag ACC_PROTECTED, corresponding to the source modifier protected, with a mask value of 0x0004.

STATIC

public static final AccessFlag STATIC
The access flag ACC_STATIC, corresponding to the source modifier static, with a mask value of 0x0008.

FINAL

public static final AccessFlag FINAL
The access flag ACC_FINAL, corresponding to the source modifier final, with a mask value of 0x0010.

SUPER

public static final AccessFlag SUPER
The access flag ACC_SUPER with a mask value of 0x0020.
API Note:
In Java SE 8 and above, the JVM treats the ACC_SUPER flag as set in every class file (JVMS 4.1).

OPEN

public static final AccessFlag OPEN
The module flag ACC_OPEN with a mask value of 0x0020.
See Also:

TRANSITIVE

public static final AccessFlag TRANSITIVE
The module requires flag ACC_TRANSITIVE with a mask value of 0x0020.
See Also:

SYNCHRONIZED

public static final AccessFlag SYNCHRONIZED
The access flag ACC_SYNCHRONIZED, corresponding to the source modifier synchronized, with a mask value of 0x0020.

STATIC_PHASE

public static final AccessFlag STATIC_PHASE
The module requires flag ACC_STATIC_PHASE with a mask value of 0x0040.
See Also:

VOLATILE

public static final AccessFlag VOLATILE
The access flag ACC_VOLATILE, corresponding to the source modifier volatile, with a mask value of 0x0040.

BRIDGE

public static final AccessFlag BRIDGE
The access flag ACC_BRIDGE with a mask value of 0x0040
See Also:

TRANSIENT

public static final AccessFlag TRANSIENT
The access flag ACC_TRANSIENT, corresponding to the source modifier transient, with a mask value of 0x0080.

VARARGS

public static final AccessFlag VARARGS
The access flag ACC_VARARGS with a mask value of 0x0080.
See Also:

NATIVE

public static final AccessFlag NATIVE
The access flag ACC_NATIVE, corresponding to the source modifier native, with a mask value of 0x0100.

INTERFACE

public static final AccessFlag INTERFACE
The access flag ACC_INTERFACE with a mask value of 0x0200.
See Also:

ABSTRACT

public static final AccessFlag ABSTRACT
The access flag ACC_ABSTRACT, corresponding to the source modifier abstract, with a mask value of 0x0400.

STRICT

public static final AccessFlag STRICT
The access flag ACC_STRICT, corresponding to the source modifier strictfp, with a mask value of 0x0800.
API Note:
The ACC_STRICT access flag is defined for class file major versions 46 through 60, inclusive (JVMS 4.6), corresponding to Java SE 1.2 through 16.

SYNTHETIC

public static final AccessFlag SYNTHETIC
The access flag ACC_SYNTHETIC with a mask value of 0x1000.
See Also:

ANNOTATION

public static final AccessFlag ANNOTATION
The access flag ACC_ANNOTATION with a mask value of 0x2000.
See Also:

ENUM

public static final AccessFlag ENUM
The access flag ACC_ENUM with a mask value of 0x4000.
See Also:

MANDATED

public static final AccessFlag MANDATED
The access flag ACC_MANDATED with a mask value of 0x8000.

MODULE

public static final AccessFlag MODULE
The access flag ACC_MODULE with a mask value of 0x8000.

Method Details

values

public static AccessFlag[] values()
Returns an array containing the constants of this enum class, in the order they are declared.
Returns:
an array containing the constants of this enum class, in the order they are declared

valueOf

public static AccessFlag valueOf(String name)
Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)
Parameters:
name - the name of the enum constant to be returned.
Returns:
the enum constant with the specified name
Throws:
IllegalArgumentException - if this enum class has no constant with the specified name
NullPointerException - if the argument is null

mask

public int mask()
Returns the corresponding integer mask for the access flag.
Returns:
the corresponding integer mask for the access flag

sourceModifier

public boolean sourceModifier()
Returns whether or not the flag has a directly corresponding modifier in the Java programming language.
Returns:
whether or not the flag has a directly corresponding modifier in the Java programming language

locations

public Set<AccessFlag.Location> locations()
Returns kinds of constructs the flag can be applied to in the latest class file format version.
Returns:
kinds of constructs the flag can be applied to in the latest class file format version

locations

public Set<AccessFlag.Location> locations(ClassFileFormatVersion cffv)
Returns kinds of constructs the flag can be applied to in the given class file format version.
Parameters:
cffv - the class file format version to use
Returns:
kinds of constructs the flag can be applied to in the given class file format version
Throws:
NullPointerException - if the parameter is null

maskToAccessFlags

public static Set<AccessFlag> maskToAccessFlags(int mask, AccessFlag.Location location)
Returns an unmodifiable set of access flags for the given mask value appropriate for the location in question.
Parameters:
mask - bit mask of access flags
location - context to interpret mask value
Returns:
an unmodifiable set of access flags for the given mask value appropriate for the location in question
Throws:
IllegalArgumentException - if the mask contains bit positions not support for the location in question

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Documentation extracted from Debian's OpenJDK Development Kit package.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/reflect/AccessFlag.html