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Java 27 and 26: runnable demos and captured output for every JEP, plus version lanes

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Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3
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asmhatre
2026-09-21 15:08:50 +00:00
committed by Claude
co-authored by Claude Sonnet 5
commit f59c1de96d
152 changed files with 5049 additions and 0 deletions
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docs/output/12-headers-jdk27-opt-out.txt
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java.version = 27
# WARNING: Unable to attach Serviceability Agent. sun.jvm.hotspot.runtime.VM.isCompressedKlassPointersEnabled()
# VM mode: 64 bits
# Compressed references (oops): 3-bit shift
# Compressed class pointers: 3-bit shift
# WARNING | Compressed references base/shifts are guessed by the experiment!
# WARNING | Therefore, computed addresses are just guesses, and ARE NOT RELIABLE.
# WARNING | Make sure to attach Serviceability Agent to get the reliable addresses.
# Object alignment: 8 bytes
# ref, bool, byte, char, shrt, int, flt, lng, dbl
# Field sizes: 4, 1, 1, 2, 2, 4, 4, 8, 8
# Array element sizes: 4, 1, 1, 2, 2, 4, 4, 8, 8
# Array base offsets: 16, 16, 16, 16, 16, 16, 16, 16, 16
=== java.lang.Object
java.lang.Object object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) N/A
8 4 (object header: class) N/A
12 4 (object alignment gap)
Instance size: 16 bytes
Space losses: 0 bytes internal + 4 bytes external = 4 bytes total
=== Point { int x; int y; }
HeaderDemo$Point object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) N/A
8 4 (object header: class) N/A
12 4 int Point.x N/A
16 4 int Point.y N/A
20 4 (object alignment gap)
Instance size: 24 bytes
Space losses: 0 bytes internal + 4 bytes external = 4 bytes total
=== Order { long id; int quantity; boolean paid; String customer; }
HeaderDemo$Order object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) N/A
8 4 (object header: class) N/A
12 4 int Order.quantity N/A
16 8 long Order.id N/A
24 1 boolean Order.paid N/A
25 3 (alignment/padding gap)
28 4 java.lang.String Order.customer N/A
Instance size: 32 bytes
Space losses: 3 bytes internal + 0 bytes external = 3 bytes total
=== java.lang.Long and java.lang.Integer (boxed values)
java.lang.Long object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) 0x0000000000000009 (non-biasable; age: 1)
8 4 (object header: class) 0x001aa208
12 4 (alignment/padding gap)
16 8 long Long.value 123456789
Instance size: 24 bytes
Space losses: 4 bytes internal + 0 bytes external = 4 bytes total
java.lang.Integer object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) 0x0000000000000001 (non-biasable; age: 0)
8 4 (object header: class) 0x001a7db8
12 4 int Integer.value 123456
Instance size: 16 bytes
Space losses: 0 bytes internal + 0 bytes external = 0 bytes total
=== int[3]
[I object internals:
OFF SZ TYPE DESCRIPTION VALUE
0 8 (object header: mark) 0x0000000000000001 (non-biasable; age: 0)
8 4 (object header: class) 0x00176c00
12 4 (array length) 3
16 12 int [I.<elements> N/A
28 4 (object alignment gap)
Instance size: 32 bytes
Space losses: 0 bytes internal + 4 bytes external = 4 bytes total
=== What it adds up to: one million objects
1,000,000 boxed Integer values in an ArrayList : 20,861,992 bytes
1,000,000 boxed Long values in an ArrayList : 28,861,992 bytes
1,000,000 Point objects in an ArrayList : 28,861,992 bytes