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Published inMar 2024
PublisherPackt
ISBN-139781837633944
Edition2nd Edition
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Anghel Leonard
Anghel Leonard
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Anghel Leonard

Anghel Leonard is a Chief Technology Strategist and independent consultant with 20+ years of experience in the Java ecosystem. In daily work, he is focused on architecting and developing Java distributed applications that empower robust architectures, clean code, and high-performance. Also passionate about coaching, mentoring and technical leadership. He is the author of several books, videos and dozens of articles related to Java technologies.
Read more about Anghel Leonard

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154. Shaping C-like unions into memory segments

Let’s consider the C-like union from the following figure (the members of a C union share the same memory location (the member’s largest data type dictates the size of the memory location), so only one of the members has a value at any moment in time):

Figure 7.18.png

Figure 7.15: A C-like union

In Figure 7.15, we have a C-like union named product to shape two members, price (double) and sku (int), while only one can have a value at any moment in time. We can shape a memory segment to fit this model as follows (arena is an instance of Arena):

MemorySegment segment = arena.allocate(
  ValueLayout.JAVA_DOUBLE.byteSize(),
  ValueLayout.JAVA_DOUBLE.byteAlignment());

Because double needs 8 bytes and int needs only 4 bytes, we choose ValueLayout.JAVA_DOUBLE to shape the size of the memory segment. This way, the segment can accommodate a double and an int at the same offset.

Next, we can set the price or the sku and...

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Java Coding Problems - Second Edition
Published in: Mar 2024Publisher: PacktISBN-13: 9781837633944

Author (1)

author image
Anghel Leonard

Anghel Leonard is a Chief Technology Strategist and independent consultant with 20+ years of experience in the Java ecosystem. In daily work, he is focused on architecting and developing Java distributed applications that empower robust architectures, clean code, and high-performance. Also passionate about coaching, mentoring and technical leadership. He is the author of several books, videos and dozens of articles related to Java technologies.
Read more about Anghel Leonard