Claude
c51641b7db
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b7rnC7jppGGdHGESvy
14 lines
1015 B
Plaintext
14 lines
1015 B
Plaintext
Q1 eager: getInstance() == getInstance() -> true
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Q2 naive lazy, 8 threads: distinct instances=more than 1 constructor runs=8
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Q3 synchronized, 8 threads: distinct instances=1 constructor runs=1
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Q4 DCL with volatile, 8 threads: distinct instances=1 constructor runs=1
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Q4 DclSingleton.instance volatile? true
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Q4 DclWithoutVolatile.instance volatile? false
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Q5 holder before first getInstance(): constructor runs=0
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Q5 holder after two getInstance() calls: constructor runs=1 same=true
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Q6 serialisation round trip keeps the same instance? classic=false hardened(readResolve)=true enum=true
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Q6 reflection newInstance() on classic private constructor returns the singleton? false
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Q6 reflection on hardened constructor: InvocationTargetException caused by java.lang.IllegalStateException: already initialised
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Q6 reflection on enum constructor: java.lang.IllegalArgumentException: Cannot reflectively create enum objects
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Q7 Spring singleton scope: same bean twice from one context? true; same bean across two contexts? false
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