Example of struct access with layouts and heap segments

Test.java

import java.lang.foreign.MemoryLayout;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.SequenceLayout;
import java.lang.foreign.ValueLayout;
import java.lang.invoke.VarHandle;

public class Test {

    static final ValueLayout.OfChar JAVA_CHAR_UNALIGNED = ValueLayout.JAVA_CHAR.withBitAlignment(8);
    static final ValueLayout.OfInt JAVA_INT_UNALIGNED  = ValueLayout.JAVA_INT.withBitAlignment(8);

    public static void main(String[] args) {
        // a layout
        SequenceLayout tagValues = MemoryLayout.sequenceLayout(
                5, MemoryLayout.structLayout(
                        JAVA_CHAR_UNALIGNED.withName("tag"),
                        JAVA_INT_UNALIGNED.withName("value"))
        );
        // a var handle to read all the fields "tag"
        VarHandle handle_tag = tagValues.varHandle(
                MemoryLayout.PathElement.sequenceElement(),
                MemoryLayout.PathElement.groupElement("tag"));
        // a var handle to read all the fields "value"
        VarHandle handle_value = tagValues.varHandle(
                MemoryLayout.PathElement.sequenceElement(),
                MemoryLayout.PathElement.groupElement("value"));
        // create an heap segment that is big enough
        MemorySegment segment = MemorySegment.ofArray(new byte[(int)tagValues.byteSize()]);
        // create some values
        char[] tags = { 'a', 'b', 'c', 'd', 'e' };
        int[] values = { 1, 2, 3, 4, 5 };
        // set the values into the segment
        for (int i = 0 ; i < tagValues.elementCount() ; i++) {
            handle_tag.set(segment, (long)i, tags[i]);
            handle_value.set(segment, (long)i, values[i]);
        }
        // print the struct fields
        for (int i = 0 ; i < tagValues.elementCount() ; i++) {
            char tag = (char)handle_tag.get(segment, (long)i);
            int value = (int)handle_value.get(segment, (long)i);
            System.out.printf("Struct #%d = { tag = %c ; value = %d } \n", i, tag, value);
        }
    }
}

Apparently, this code requires JDK18. Is there a way to do the same with JDK17?