Enum Class TypeKind

java.lang.Object

java.lang.Enum<TypeKind^PREVIEW>

java.lang.classfile.TypeKind

All Implemented Interfaces:

Serializable, Comparable<TypeKindPREVIEW>, Constable

public enum TypeKind
extends Enum<TypeKindPREVIEW>

TypeKind is a preview API of the Java platform.

Programs can only use TypeKind when preview features are enabled.

Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.

Describes the data types Java Virtual Machine operates on. This omits returnAddress (JVMS 2.3.3), which is only used by discontinued jsr^PREVIEW and ret^PREVIEW instructions, and includes void (JVMS 4.3.3), which appears as a method return type.

Computational Type

In the class file format, local variables (JVMS 2.6.1), and the operand stack (JVMS 2.6.2) of the Java Virtual Machine, boolean, byte, char, short types do not exist and are represented by the int computational type. int, float, reference, returnAddress, long, and doule are the computational types of the Java Virtual Machine.

See Java Virtual Machine Specification:

2.2 Data Types
2.11.1 Types and the Java Virtual Machine

Since:

22

Nested Class Summary

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

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constants

Enum Constant	Description
BOOLEAN	The primitive type boolean.
BYTE	The primitive type byte.
CHAR	The primitive type char.
DOUBLE	The primitive type double.
FLOAT	The primitive type float.
INT	The primitive type int.
LONG	The primitive type long.
REFERENCE	A reference type.
SHORT	The primitive type short.
VOID	The void type, for absence of a value.

Method Summary

Modifier and Type	Method	Description
TypeKindPREVIEW	asLoadable()	Returns the computational type for this type, or void for void.
static TypeKindPREVIEW	from(TypeDescriptor.OfField<?> descriptor)	Returns the type associated with the specified field descriptor.
static TypeKindPREVIEW	fromDescriptor(CharSequence s)	Returns the type associated with the specified field descriptor.
static TypeKindPREVIEW	fromNewarrayCode(int newarrayCode)	Returns the component type described by the array code used as an operand to newarrayPREVIEW.
int	newarrayCode()	Returns the code used by the newarrayPREVIEW instruction to create an array of this component type, or -1 if this type is not supported by newarray.
int	slotSize()	Returns the number of local variable index or operand stack depth consumed by this type.
ClassDesc	upperBound()	Returns the most specific upper bound field descriptor that can store any value of this type.
static TypeKindPREVIEW	valueOf(String name)	Returns the enum constant of this class with the specified name.
static TypeKindPREVIEW[]	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

BOOLEAN

public static final TypeKindPREVIEW BOOLEAN

The primitive type boolean. Its computational type is int. 0 represents false, and 1 represents true. It is zero-extended to an int when loaded onto the operand stack and narrowed by taking the bitwise AND with 1 when stored.

See Java Virtual Machine Specification:

2.3.4 The boolean Type

BYTE

public static final TypeKindPREVIEW BYTE

The primitive type byte. Its computational type is int. It is sign-extended to an int when loaded onto the operand stack and truncated when stored.

CHAR

public static final TypeKindPREVIEW CHAR

The primitive type char. Its computational type is int. It is zero-extended to an int when loaded onto the operand stack and truncated when stored.

SHORT

public static final TypeKindPREVIEW SHORT

The primitive type short. Its computational type is int. It is sign-extended to an int when loaded onto the operand stack and truncated when stored.

INT

public static final TypeKindPREVIEW INT

The primitive type int.

LONG

public static final TypeKindPREVIEW LONG

The primitive type long. It is of category 2.

FLOAT

public static final TypeKindPREVIEW FLOAT

The primitive type float.

DOUBLE

public static final TypeKindPREVIEW DOUBLE

The primitive type double. It is of category 2.

REFERENCE

public static final TypeKindPREVIEW REFERENCE

A reference type.

See Java Virtual Machine Specification:

2.4 Reference Types and Values

VOID

public static final TypeKindPREVIEW VOID

The void type, for absence of a value. While this is not a data type, this can be a method return type indicating no change in operand stack depth.

See Java Virtual Machine Specification:

4.3.3 Method Descriptors

Method Details

values

public static TypeKindPREVIEW[] 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 TypeKindPREVIEW 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

upperBound

public ClassDesc upperBound()

Returns the most specific upper bound field descriptor that can store any value of this type. This is the primitive class descriptor for primitive types and void and Object descriptor for reference.

Returns:

the most specific upper bound field descriptor that can store any value of this type

newarrayCode

public int newarrayCode()

Returns the code used by the newarray^PREVIEW instruction to create an array of this component type, or -1 if this type is not supported by newarray.

Returns:

the code used by the newarray^PREVIEW instruction to create an array of this component type, or -1 if this type is not supported by newarray

See Java Virtual Machine Specification:

6.5.newarray newarray

Since:

23

slotSize

public int slotSize()

Returns the number of local variable index or operand stack depth consumed by this type. This is also the category of this type for instructions operating on the operand stack without regard to type (JVMS 2.11.1), such as pop^PREVIEW versus pop2^PREVIEW.

Returns:

the number of local variable index or operand stack depth consumed by this type

See Java Virtual Machine Specification:

2.6.1 Local Variables
2.6.2 Operand Stacks

asLoadable

public TypeKindPREVIEW asLoadable()

Returns the computational type for this type, or void for void.

Returns:

the computational type for this type, or void for void

fromNewarrayCode

public static TypeKindPREVIEW fromNewarrayCode(int newarrayCode)

Returns the component type described by the array code used as an operand to newarray^PREVIEW.

Parameters:

newarrayCode - the operand of the newarray instruction

Returns:

the component type described by the array code used as an operand to newarray^PREVIEW

Throws:

IllegalArgumentException - if the code is invalid

See Java Virtual Machine Specification:

6.5.newarray newarray

Since:

23

fromDescriptor

public static TypeKindPREVIEW fromDescriptor(CharSequence s)

Returns the type associated with the specified field descriptor.

Parameters:

s - the field descriptor

Returns:

the type associated with the specified field descriptor

Throws:

IllegalArgumentException - only if the descriptor is not valid

from

public static TypeKindPREVIEW from(TypeDescriptor.OfField<?> descriptor)

Returns the type associated with the specified field descriptor.

Parameters:

descriptor - the field descriptor

Returns:

the type associated with the specified field descriptor