Module java.base

Package java.lang.foreign

Interface UnionLayout

All Superinterfaces:

GroupLayoutPREVIEW, MemoryLayoutPREVIEW

public sealed interface UnionLayout
extends GroupLayoutPREVIEW

UnionLayout is a preview API of the Java platform.

Programs can only use UnionLayout when preview features are enabled.

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

A group layout whose member layouts are laid out at the same starting offset.

Implementation Requirements:

Implementing classes are immutable, thread-safe and value-based.

Since:

20

Nested Class Summary

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

MemoryLayout.PathElementPREVIEW

Method Summary

Modifier and Type	Method	Description
UnionLayoutPREVIEW	withByteAlignment(long byteAlignment)	Returns a memory layout of the same type with the same size and name as this layout, but with the specified alignment constraint (in bytes).
UnionLayoutPREVIEW	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.
UnionLayoutPREVIEW	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.GroupLayout^PREVIEW

memberLayouts

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

byteAlignment, byteOffset, byteOffsetHandle, byteSize, equals, hashCode, name, select, sliceHandle, toString, varHandle

Method Details

withName

UnionLayoutPREVIEW 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 GroupLayoutPREVIEW

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

UnionLayoutPREVIEW 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 GroupLayoutPREVIEW

Specified by:

withoutName in interface MemoryLayoutPREVIEW

Returns:

a memory layout without a name.

See Also:

• MemoryLayout.name()^PREVIEW

withByteAlignment

UnionLayoutPREVIEW withByteAlignment(long byteAlignment)

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

Specified by:

withByteAlignment in interface GroupLayoutPREVIEW

Specified by:

withByteAlignment in interface MemoryLayoutPREVIEW

Parameters:

byteAlignment - the layout alignment constraint, expressed in bytes.

Returns:

a memory layout with the given alignment constraint.

Throws:

IllegalArgumentException - if byteAlignment is not a power of two, or if it's less than 1.

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