Interface ValueLayout
- All Superinterfaces:
MemoryLayout
- All Known Subinterfaces:
AddressLayout,ValueLayout.OfBoolean,ValueLayout.OfByte,ValueLayout.OfChar,ValueLayout.OfDouble,ValueLayout.OfFloat,ValueLayout.OfInt,ValueLayout.OfLong,ValueLayout.OfShort
Each value layout has a size, an alignment (both expressed in bytes), a byte order, and a carrier, that is, the Java type that should be used when accessing a region of memory using the value layout.
This class defines useful value layout constants for Java primitive types and addresses.
- API Note:
- Some characteristics of the Java layout constants are platform-dependent.
For instance, the byte order of these constants is set to the
native byte order, thus making it easy
to work with other APIs, such as arrays and
ByteBuffer. - Implementation Requirements:
- implementing classes and subclasses are immutable, thread-safe and value-based.
- Sealed Class Hierarchy Graph:
- Since:
- 22
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Nested Class Summary
Nested ClassesModifier and TypeInterfaceDescriptionstatic interfaceA value layout whose carrier isboolean.class.static interfaceA value layout whose carrier isbyte.class.static interfaceA value layout whose carrier ischar.class.static interfaceA value layout whose carrier isdouble.class.static interfaceA value layout whose carrier isfloat.class.static interfaceA value layout whose carrier isint.class.static interfaceA value layout whose carrier islong.class.static interfaceA value layout whose carrier isshort.class.Nested classes/interfaces declared in interface java.lang.foreign.MemoryLayout
MemoryLayout.PathElement -
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final AddressLayoutAn address layout constant whose size is the same as that of a machine address (size_t), byte alignment set tosizeof(size_t), byte order set toByteOrder.nativeOrder().static final AddressLayoutAn unaligned address layout constant whose size is the same as that of a machine address (size_t), and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfBooleanA value layout constant whose size is the same as that of a Javaboolean, byte alignment set to 1, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfByteA value layout constant whose size is the same as that of a Javabyte, byte alignment set to 1, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfCharA value layout constant whose size is the same as that of a Javachar, byte alignment set to 2, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfCharAn unaligned value layout constant whose size is the same as that of a Javacharand byte order set toByteOrder.nativeOrder().static final ValueLayout.OfDoubleA value layout constant whose size is the same as that of a Javadouble, byte alignment set to 8, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfDoubleAn unaligned value layout constant whose size is the same as that of a Javadoubleand byte order set toByteOrder.nativeOrder().static final ValueLayout.OfFloatA value layout constant whose size is the same as that of a Javafloat, byte alignment set to 4, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfFloatAn unaligned value layout constant whose size is the same as that of a Javafloatand byte order set toByteOrder.nativeOrder().static final ValueLayout.OfIntA value layout constant whose size is the same as that of a Javaint, byte alignment set to 4, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfIntAn unaligned value layout constant whose size is the same as that of a Javaintand byte order set toByteOrder.nativeOrder().static final ValueLayout.OfLongA value layout constant whose size is the same as that of a Javalong, byte alignment set to 8, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfLongAn unaligned value layout constant whose size is the same as that of a Javalongand byte order set toByteOrder.nativeOrder().static final ValueLayout.OfShortA value layout constant whose size is the same as that of a Javashort, byte alignment set to 2, and byte order set toByteOrder.nativeOrder().static final ValueLayout.OfShortAn unaligned value layout constant whose size is the same as that of a Javashortand byte order set toByteOrder.nativeOrder(). -
Method Summary
Modifier and TypeMethodDescriptionClass<?> carrier()Returns the carrier associated with this value layout.order()Returns the value's byte order.Returns a var handle which can be used to access values described by this value layout, in a given memory segment.withByteAlignment(long byteAlignment) Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes).Returns a memory layout with the same characteristics as this layout, but with the given name.Returns a value layout with the same characteristics as this layout, but with the given byte order.Returns a memory layout with the same characteristics as this layout, but with no name.Methods declared in interface java.lang.foreign.MemoryLayout
arrayElementVarHandle, byteAlignment, byteOffset, byteOffsetHandle, byteSize, equals, hashCode, name, scale, scaleHandle, select, sliceHandle, toString, varHandle
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Field Details
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ADDRESS
An address layout constant whose size is the same as that of a machine address (size_t), byte alignment set tosizeof(size_t), byte order set toByteOrder.nativeOrder(). -
JAVA_BYTE
A value layout constant whose size is the same as that of a Javabyte, byte alignment set to 1, and byte order set toByteOrder.nativeOrder(). -
JAVA_BOOLEAN
A value layout constant whose size is the same as that of a Javaboolean, byte alignment set to 1, and byte order set toByteOrder.nativeOrder(). -
JAVA_CHAR
A value layout constant whose size is the same as that of a Javachar, byte alignment set to 2, and byte order set toByteOrder.nativeOrder(). -
JAVA_SHORT
A value layout constant whose size is the same as that of a Javashort, byte alignment set to 2, and byte order set toByteOrder.nativeOrder(). -
JAVA_INT
A value layout constant whose size is the same as that of a Javaint, byte alignment set to 4, and byte order set toByteOrder.nativeOrder(). -
JAVA_LONG
A value layout constant whose size is the same as that of a Javalong, byte alignment set to 8, and byte order set toByteOrder.nativeOrder(). -
JAVA_FLOAT
A value layout constant whose size is the same as that of a Javafloat, byte alignment set to 4, and byte order set toByteOrder.nativeOrder(). -
JAVA_DOUBLE
A value layout constant whose size is the same as that of a Javadouble, byte alignment set to 8, and byte order set toByteOrder.nativeOrder(). -
ADDRESS_UNALIGNED
An unaligned address layout constant whose size is the same as that of a machine address (size_t), and byte order set toByteOrder.nativeOrder(). Equivalent to the following code:ADDRESS.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_CHAR_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javacharand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_CHAR.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_SHORT_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javashortand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_SHORT.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_INT_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javaintand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_INT.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_LONG_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javalongand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_LONG.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_FLOAT_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javafloatand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_FLOAT.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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JAVA_DOUBLE_UNALIGNED
An unaligned value layout constant whose size is the same as that of a Javadoubleand byte order set toByteOrder.nativeOrder(). Equivalent to the following code:JAVA_DOUBLE.withByteAlignment(1);- API Note:
- Care should be taken when using unaligned value layouts as they may induce performance and portability issues.
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Method Details
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order
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withOrder
Returns a value layout with the same characteristics as this layout, but with the given byte order.- Parameters:
order- the desired byte order- Returns:
- a value layout with the same characteristics as this layout, but with the given byte order
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withoutName
ValueLayout withoutName()Returns a memory layout with the same characteristics as this layout, but with no name.- Specified by:
withoutNamein interfaceMemoryLayout- Returns:
- a memory layout with the same characteristics as this layout, but with no name
- See Also:
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carrier
Class<?> carrier()Returns the carrier associated with this value layout.- Returns:
- the carrier associated with this value layout
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withName
Returns a memory layout with the same characteristics as this layout, but with the given name.- Specified by:
withNamein interfaceMemoryLayout- Parameters:
name- the layout name- Returns:
- a memory layout with the same characteristics as this layout, but with the given name
- See Also:
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withByteAlignment
Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes).- Specified by:
withByteAlignmentin interfaceMemoryLayout- Parameters:
byteAlignment- the layout alignment constraint, expressed in bytes- Returns:
- a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes)
- Throws:
IllegalArgumentException- ifbyteAlignmentis not a power of two
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varHandle
VarHandle varHandle()Returns a var handle which can be used to access values described by this value layout, in a given memory segment.The returned var handle's var type is the carrier type of this value layout, and the list of coordinate types is
(MemorySegment, long), where the memory segment coordinate corresponds to the memory segment to be accessed, and thelongcoordinate corresponds to the byte offset into the accessed memory segment at which the access occurs.The returned var handle checks that accesses are aligned according to this value layout's alignment constraint.
- API Note:
- This method is similar, but more efficient than calling
MemoryLayout#varHandle(PathElement...)with an empty path element array, as it avoids the creation of the var args array., The returned var handle features certain access mode restrictions common to all memory access var handles derived from memory layouts. - Returns:
- a var handle which can be used to access values described by this value layout, in a given memory segment
- See Also:
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