OpenJDK 27 · java.lang.classfile.TypeKind · APIdia, the JavaDoc alternative

Describes the data types Java Virtual Machine operates on. This omits returnAddress (JVMS 2.3.3) and includes void (JVMS 4.3.3), which appears as a method return type.

The returnAddress type is only used by discontinued jump subroutine and return from subroutine instructions. Jump subroutine instructions push returnAddress to the operand stack; astore instructions store returnAddress from the operand stack to local variables; return from subroutine instructions load returnAddress from local variables.

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.

Field Summary

Modifier and Type	Field and Description
public static final TypeKind	BOOLEAN The primitive type `boolean`.
public static final TypeKind	BYTE The primitive type `byte`.
public static final TypeKind	CHAR The primitive type `char`.
public static final TypeKind	DOUBLE The primitive type `double`.
public static final TypeKind	FLOAT The primitive type `float`.
public static final TypeKind	INT The primitive type `int`.
public static final TypeKind	LONG The primitive type `long`.
private final int	newarrayCode
public static final TypeKind	REFERENCE A reference type.
public static final TypeKind	SHORT The primitive type `short`.
private final int	slots
private ClassDesc	upperBound
public static final TypeKind	VOID The `void` type, for absence of a value.

Constructor Summary

Access	Constructor and Description
private	TypeKind(int slots, int newarrayCode)

Method Summary

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

Inherited from java.lang.Enum:: clone compareTo describeConstable equals finalize getDeclaringClass hashCode name ordinal toString valueOf

Field Detail

BOOLEAN back to summary

BOOLEAN	back to summary
public static final TypeKind 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. Java Virtual Machine Specification 2.3.4 The `boolean` Type

public static final TypeKind 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.

Java Virtual Machine Specification: 2.3.4 The boolean Type

BYTE	back to summary
public static final TypeKind 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	back to summary
public static final TypeKind 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.

DOUBLE	back to summary
public static final TypeKind DOUBLE The primitive type `double`. It is of category 2. All NaN values of `double` may or may not be collapsed into a single "canonical" NaN value in loading and storing.

FLOAT	back to summary
public static final TypeKind FLOAT The primitive type `float`. All NaN values of `float` may or may not be collapsed into a single "canonical" NaN value in loading and storing.

INT	back to summary
public static final TypeKind INT The primitive type `int`.

LONG	back to summary
public static final TypeKind LONG The primitive type `long`. It is of category 2.

newarrayCode	back to summary
private final int newarrayCode

REFERENCE	back to summary
public static final TypeKind REFERENCE A reference type. Java Virtual Machine Specification 2.4 Reference Types and Values

REFERENCE

back to summary

public static final TypeKind REFERENCE

A reference type.

Java Virtual Machine Specification: 2.4 Reference Types and Values

SHORT	back to summary
public static final TypeKind 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.

slots	back to summary
private final int slots

upperBound	back to summary
private ClassDesc upperBound Annotations @Stable

VOID back to summary

VOID	back to summary
public static final TypeKind 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. Java Virtual Machine Specification 4.3.3 Method Descriptors

public static final TypeKind 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.

Java Virtual Machine Specification: 4.3.3 Method Descriptors

Constructor Detail

TypeKind	back to summary
private TypeKind(int slots, int newarrayCode)

Method Detail

asLoadable back to summary

asLoadable	back to summary
public TypeKind asLoadable() Returns the computational type for this type, or `void` for `void`. Returns:TypeKind the computational type for this type, or `void` for `void` See Also `LoadInstruction`, `StoreInstruction`

public TypeKind asLoadable()

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

Returns:TypeKind: the computational type for this type, or void for void
See Also: LoadInstruction, StoreInstruction

fetchUpperBound	back to summary
private ClassDesc fetchUpperBound()

from	back to summary
public static TypeKind from(TypeDescriptor.OfField<?> descriptor) Returns the type associated with the specified field descriptor. Parameters descriptor:TypeDescriptor.OfField<?> the field descriptor Returns:TypeKind the type associated with the specified field descriptor

from

back to summary

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

Returns the type associated with the specified field descriptor.

Parameters

descriptor:TypeDescriptor.OfField<?>: the field descriptor

Returns:TypeKind

the type associated with the specified field descriptor

fromDescriptor	back to summary
public static TypeKind fromDescriptor(CharSequence s) Returns the type associated with the specified field descriptor. Parameters s:CharSequence the field descriptor Returns:TypeKind the type associated with the specified field descriptor Exceptions IllegalArgumentException: only if the descriptor is not valid

fromDescriptor

back to summary

public static TypeKind fromDescriptor(CharSequence s)

Returns the type associated with the specified field descriptor.

Parameters

s:CharSequence: the field descriptor

Returns:TypeKind

the type associated with the specified field descriptor

Exceptions

IllegalArgumentException:: only if the descriptor is not valid

fromNewarrayCode back to summary

fromNewarrayCode	back to summary
public static TypeKind fromNewarrayCode(int newarrayCode) Returns the component type described by the array code used as an operand to `newarray`. Parameters newarrayCode:int the operand of the `newarray` instruction Returns:TypeKind the component type described by the array code used as an operand to `newarray` Exceptions IllegalArgumentException: if the code is invalid Java Virtual Machine Specification 6.5.newarray newarray See Also `NewPrimitiveArrayInstruction`, `newarrayCode()`

public static TypeKind fromNewarrayCode(int newarrayCode)

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

Parameters

newarrayCode:int: the operand of the newarray instruction

Returns:TypeKind

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

Exceptions

IllegalArgumentException:: if the code is invalid

Java Virtual Machine Specification

6.5.newarray newarray

newarrayCode back to summary

newarrayCode	back to summary
public int newarrayCode() Returns the code used by the `newarray` instruction to create an array of this component type, or `-1` if this type is not supported by `newarray`. Returns:int the code used by the `newarray` instruction to create an array of this component type, or `-1` if this type is not supported by `newarray` Java Virtual Machine Specification 6.5.newarray newarray See Also `NewPrimitiveArrayInstruction`, `fromNewarrayCode(int)`

public int newarrayCode()

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

Returns:int: the code used by the newarray instruction to create an array of this component type, or -1 if this type is not supported by newarray
Java Virtual Machine Specification: 6.5.newarray newarray
See Also: NewPrimitiveArrayInstruction, fromNewarrayCode(int)

slotSize back to summary

slotSize	back to summary
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` versus `pop2`. Returns:int the number of local variable index or operand stack depth consumed by this type Java Virtual Machine Specification 2.6.1 Local Variables, 2.6.2 Operand Stacks

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 versus pop2.

Returns:int: the number of local variable index or operand stack depth consumed by this type
Java Virtual Machine Specification: 2.6.1 Local Variables, 2.6.2 Operand Stacks

upperBound back to summary

upperBound	back to summary
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:ClassDesc the most specific upper bound field descriptor that can store any value of this type

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

valueOf	back to summary
public static TypeKind valueOf(String name)

values	back to summary
public static TypeKind[] values()

public final Enum TypeKind

Computational Type

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail