Which statement is true?
Answer: C
This is a great way to think about when objects can be garbage collected.
Option A and B assume guarantees that the garbage collector never makes.
Option D is wrong because of the now famous islands of isolation scenario.
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Which statement is true?
Answer: D
All objects are placed in the garbage collectible heap.
Option A is incorrect because the garbage collector makes no guarantees.
Option B is incorrect because islands of isolated objects can exist.
Option C is incorrect because finalize() has no such mystical powers.
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Which statement is true?
Answer: B
Option B is correct. If an object can be accessed from a live thread, it can't be garbage collected.
Option A is wrong. Runtime.gc() asks the garbage collector to run, but the garbage collector never makes any guarantees about when it will run or what unreachable objects it will free from memory.
Option C is wrong. The garbage collector runs immediately the system is out of memory before an OutOfMemoryException is thrown by the JVM.
Option D is wrong. If this were the case then the garbage collector would actively hang onto objects until a program finishes - this goes against the purpose of the garbage collector.
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Which statement is true?
Answer: D
Option D is correct.
Option C is wrong. See the note above on Islands of Isolation (An object is eligible for garbage collection when no live thread can access it - even though there might be references to it).
Option B is wrong. "Never again be used" does not mean that there are no more references to the object.
Option A is wrong. Even though Java applications can run out of memory there another answer supplied that is more right.
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