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Java Coding Problems - Second Edition

You're reading from  Java Coding Problems - Second Edition

Product type Book
Published in Mar 2024
Publisher Packt
ISBN-13 9781837633944
Pages 798 pages
Edition 2nd Edition
Languages
Author (1):
Anghel Leonard Anghel Leonard
Profile icon Anghel Leonard

Table of Contents (16) Chapters

Preface Text Blocks, Locales, Numbers, and Math Objects, Immutability, Switch Expressions, and Pattern Matching Working with Date and Time Records and Record Patterns Arrays, Collections, and Data Structures Java I/O: Context-Specific Deserialization Filters Foreign (Function) Memory API Sealed and Hidden Classes Functional Style Programming – Extending APIs Concurrency – Virtual Threads and Structured Concurrency Concurrency ‒ Virtual Threads and Structured Concurrency: Diving Deeper Garbage Collectors and Dynamic CDS Archives Socket API and Simple Web Server Other Books You May Enjoy
Index

162. Introducing the memory segment view VarHandle

Let’s consider the following simple memory segment for storing an int (arena is an instance of Arena):

MemorySegment segment = arena.allocate(ValueLayout.JAVA_INT);

We know that we can create a VarHandle via PathElement:

// VarHandle[varType=int, 
// coord=[interface java.lang.foreign.MemorySegment]]
VarHandle handle = ValueLayout.JAVA_INT.varHandle();

Or, via arrayElementVarHandle():

// VarHandle[varType=int, 
// coord=[interface java.lang.foreign.MemorySegment, long]]
VarHandle arrhandle
  = ValueLayout.JAVA_INT.arrayElementVarHandle();

The MethodHandles.memorySegmentViewVarHandle(ValueLayout layout) is another approach for creating a VarHandle that can be used to access a memory segment. The returned VarHandle perceives/views the content of the memory segment as a sequence of the given ValueLayout. In our case, the code looks as follows:

// VarHandle[varType=int, 
// coord=[interface java.lang...
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