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Java Coding Problems

You're reading from   Java Coding Problems Become an expert Java programmer by solving over 250 brand-new, modern, real-world problems

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Product type Paperback
Published in Mar 2024
Publisher Packt
ISBN-13 9781837633944
Length 798 pages
Edition 2nd Edition
Languages
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Author (1):
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Anghel Leonard Anghel Leonard
Author Profile Icon Anghel Leonard
Anghel Leonard
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Table of Contents (16) Chapters Close

Preface 1. Text Blocks, Locales, Numbers, and Math 2. Objects, Immutability, Switch Expressions, and Pattern Matching FREE CHAPTER 3. Working with Date and Time 4. Records and Record Patterns 5. Arrays, Collections, and Data Structures 6. Java I/O: Context-Specific Deserialization Filters 7. Foreign (Function) Memory API 8. Sealed and Hidden Classes 9. Functional Style Programming – Extending APIs 10. Concurrency – Virtual Threads and Structured Concurrency 11. Concurrency ‒ Virtual Threads and Structured Concurrency: Diving Deeper 12. Garbage Collectors and Dynamic CDS Archives 13. Socket API and Simple Web Server 14. Other Books You May Enjoy
15. 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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