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
public sealed interfaceValueLayoutextendsMemoryLayoutpermitsValueLayout.OfBoolean,ValueLayout.OfByte,ValueLayout.OfChar,ValueLayout.OfShort,ValueLayout.OfInt,ValueLayout.OfFloat,ValueLayout.OfLong,ValueLayout.OfDouble,AddressLayout
A layout that models values of basic data types. Examples of values modeled bya value layout areintegral values (either signed or unsigned),floating-point values andaddress values.

Each value layout has a size, an alignment (both expressed in bytes),abyte order, and acarrier, that is, the Java typethat should be used whenaccessing aregion of memory using the value layout.

This class defines useful value layout constants for Java primitive types andaddresses.

API Note:
Some characteristics of the Java layout constants are platform-dependent. For instance, the byte order of these constants is set to thenative byte order, thus making it easy to work with other APIs, such as arrays andByteBuffer.
Implementation Requirements:
implementing classes and subclasses are immutable, thread-safe andvalue-based.
Sealed Class Hierarchy Graph:
Sealed class hierarchy graph for ValueLayoutSealed class hierarchy graph for ValueLayout
Since:
22

  • Field Details

    • ADDRESS

      static final AddressLayout ADDRESS
      An address layout constant whose size is the same as that of amachine address (size_t), byte alignment set tosizeof(size_t),byte order set toByteOrder.nativeOrder().

    • JAVA_BYTE

      static final ValueLayout.OfByte 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

      static final ValueLayout.OfBoolean 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

      static final ValueLayout.OfChar 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

      static final ValueLayout.OfShort 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

      static final ValueLayout.OfInt 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

      static final ValueLayout.OfLong 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

      static final ValueLayout.OfFloat 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

      static final ValueLayout.OfDouble 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

      static final AddressLayout ADDRESS_UNALIGNED
      An unaligned address layout constant whose size is the same as that of amachine 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.

    • JAVA_CHAR_UNALIGNED

      static final ValueLayout.OfChar 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.

    • JAVA_SHORT_UNALIGNED

      static final ValueLayout.OfShort 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.

    • JAVA_INT_UNALIGNED

      static final ValueLayout.OfInt 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.

    • JAVA_LONG_UNALIGNED

      static final ValueLayout.OfLong 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.

    • JAVA_FLOAT_UNALIGNED

      static final ValueLayout.OfFloat 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.

    • JAVA_DOUBLE_UNALIGNED

      static final ValueLayout.OfDouble 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.

  • Method Details

    • order

      ByteOrder order()
      Returns the value's byte order.
      Returns:
      the value's byte order

    • withOrder

      ValueLayout withOrder(ByteOrder order)
      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

    • withoutName

      ValueLayout withoutName()
      Returns a memory layout with the same characteristics as this layout, but with no name.
      Specified by:
      withoutName in interface MemoryLayout
      Returns:
      a memory layout with the same characteristics as this layout, but with no name
      See Also:

    • carrier

      Class<?> carrier()
      Returns the carrier associated with this value layout.
      Returns:
      the carrier associated with this value layout

    • withName

      ValueLayout withName(String name)
      Returns a memory layout with the same characteristics as this layout, but with the given name.
      Specified by:
      withName in interface MemoryLayout
      Parameters:
      name - the layout name
      Returns:
      a memory layout with the same characteristics as this layout, but with the given name
      See Also:

    • withByteAlignment

      ValueLayout withByteAlignment(long byteAlignment)
      Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes).
      Specified by:
      withByteAlignment in interface MemoryLayout
      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 - ifbyteAlignment is not a power of two

    • 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'svar type is thecarrier type of this value layout, and thelist of coordinate types is(MemorySegment, long), where thememory segment coordinate corresponds to the memory segment to be accessed, andthelong coordinate corresponds to the byte offset into the accessedmemory segment at which the access occurs.

      The returned var handle checks that accesses are aligned according tothis value layout'salignment constraint.

      API Note:
      This method is similar, but more efficient than callingMemoryLayout#varHandle(PathElement...) with an empty path element array, as it avoids the creation of the var args array., The returned var handle features certainaccess 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: