Practice · 2 of 3
The identity matrix
CHALLENGE
Difficulty: advanced+25 XP
Implement four static predicates — each must use == (identity), not equals:
1. static boolean pooledLiterals() — is "jvm" == "jvm" (two literals)?
2. static boolean newStringSameAsLiteral() — is new String("jvm") == "jvm"?
3. static boolean internedMatches() — is new String("jvm").intern() == "jvm"?
4. static boolean boxCacheHolds() — is Integer.valueOf(127) == Integer.valueOf(127)?
5. static boolean boxCacheMisses() — is Integer.valueOf(128) == Integer.valueOf(128)?
6. static boolean bigBoxSame() — is Integer.valueOf(1000) == Integer.valueOf(1000)?
Return the *actual* results, whatever they are — the tests know the truth.
Press Submit to check your solution.
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