Module java.base

Package java.lang.foreign

Interface GroupLayout

All Superinterfaces:

MemoryLayoutPREVIEW

All Known Subinterfaces:

StructLayoutPREVIEW, UnionLayoutPREVIEW

public sealed interface GroupLayout
extends MemoryLayoutPREVIEW
permits StructLayoutPREVIEW, UnionLayoutPREVIEW

GroupLayout is a preview API of the Java platform.

Programs can only use GroupLayout when preview features are enabled.

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

A compound layout that aggregates multiple member layouts. There are two ways in which member layouts can be combined: if member layouts are laid out one after the other, the resulting group layout is said to be a struct layout (see MemoryLayout.structLayout(MemoryLayout...)^PREVIEW); conversely, if all member layouts are laid out at the same starting offset, the resulting group layout is said to be a union layout (see MemoryLayout.unionLayout(MemoryLayout...)^PREVIEW).

Implementation Requirements:

This class is immutable, thread-safe and value-based.

Since:

19

Nested Class Summary

Nested classes/interfaces declared in interface java.lang.foreign.MemoryLayout^PREVIEW

MemoryLayout.PathElementPREVIEW

Method Summary

Modifier and Type	Method	Description
List<MemoryLayoutPREVIEW>	memberLayouts()	Returns the member layouts associated with this group.
GroupLayoutPREVIEW	withBitAlignment(long bitAlignment)	Returns a memory layout of the same type with the same size and name as this layout, but with the specified alignment constraint (in bits).
GroupLayoutPREVIEW	withName(String name)	Returns a memory layout of the same type with the same size and alignment constraint as this layout, but with the specified name.
GroupLayoutPREVIEW	withoutName()	Returns a memory layout of the same type with the same size and alignment constraint as this layout, but without a name.

Methods declared in interface java.lang.foreign.MemoryLayout^PREVIEW

bitAlignment, bitOffset, bitOffsetHandle, bitSize, byteAlignment, byteOffset, byteOffsetHandle, byteSize, equals, hashCode, name, select, sliceHandle, toString, varHandle

Method Details

memberLayouts

List<MemoryLayoutPREVIEW> memberLayouts()

Returns the member layouts associated with this group.

API Note:

the order in which member layouts are returned is the same order in which member layouts have been passed to one of the group layout factory methods (see MemoryLayout.structLayout(MemoryLayout...)^PREVIEW, MemoryLayout.unionLayout(MemoryLayout...)^PREVIEW).

Returns:

the member layouts associated with this group.

withName

GroupLayoutPREVIEW withName(String name)

Returns a memory layout of the same type with the same size and alignment constraint as this layout, but with the specified name.

Specified by:

withName in interface MemoryLayoutPREVIEW

Parameters:

name - the layout name.

Returns:

a memory layout with the given name.

See Also:

• MemoryLayout.name()^PREVIEW

withoutName

GroupLayoutPREVIEW withoutName()

Returns a memory layout of the same type with the same size and alignment constraint as this layout, but without a name.

This can be useful to compare two layouts that have different names, but are otherwise equal.

Specified by:

withoutName in interface MemoryLayoutPREVIEW

Returns:

a memory layout without a name.

See Also:

• MemoryLayout.name()^PREVIEW

withBitAlignment

GroupLayoutPREVIEW withBitAlignment(long bitAlignment)

Returns a memory layout of the same type with the same size and name as this layout, but with the specified alignment constraint (in bits).

Specified by:

withBitAlignment in interface MemoryLayoutPREVIEW

Parameters:

bitAlignment - the layout alignment constraint, expressed in bits.

Returns:

a memory layout with the given alignment constraint.

Throws:

IllegalArgumentException - if bitAlignment is not a power of two, or if it's less than 8.

IllegalArgumentException - if bitAlignment is less than M, where M is the maximum alignment constraint in any of the member layouts associated with this group layout.