Claude
c5c435ae20
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b5DfjBGLBr7F5km2AN
50 lines
2.5 KiB
Plaintext
50 lines
2.5 KiB
Plaintext
=== Q28 The Collections Framework hierarchy ===
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ArrayList extends AbstractList implements [List, RandomAccess, Cloneable, Serializable]
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LinkedList extends AbstractSequentialList implements [List, Deque, Cloneable, Serializable]
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HashSet extends AbstractSet implements [Set, Cloneable, Serializable]
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TreeSet extends AbstractSet implements [NavigableSet, Cloneable, Serializable]
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ArrayDeque extends AbstractCollection implements [Deque, Cloneable, Serializable]
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HashMap extends AbstractMap implements [Map, Cloneable, Serializable]
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TreeMap extends AbstractMap implements [NavigableMap, Cloneable, Serializable]
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=== Q29 ArrayList vs LinkedList ===
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ArrayList is RandomAccess: true
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LinkedList is RandomAccess: false
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LinkedList is also a Deque: true
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after add(0, 5): [5, 10, 20, 30], get(2) = 20
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=== Q30 How HashMap works internally ===
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Aa: hashCode=2112, bucket (16 slots)=0
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BB: hashCode=2112, bucket (16 slots)=0
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Ankur: hashCode=63412443, bucket (16 slots)=12
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both survive a collision: first, second, size 2
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=== Q31 HashMap vs Hashtable vs ConcurrentHashMap vs TreeMap ===
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HashMap: null key accepted
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Hashtable: null key throws NullPointerException
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ConcurrentHashMap: null key throws NullPointerException
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TreeMap: null key throws NullPointerException
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=== Q32 HashSet vs LinkedHashSet vs TreeSet ===
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HashSet [banana, apple, cherry, pear, mango]
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LinkedHashSet [pear, apple, mango, banana, cherry]
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TreeSet [apple, banana, cherry, mango, pear]
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=== Q33 Comparable vs Comparator ===
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natural (Comparable): [Student[name=Asha, marks=88], Student[name=Meena, marks=88], Student[name=Ravi, marks=90]]
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marks desc, then name: [Student[name=Ravi, marks=90], Student[name=Asha, marks=88], Student[name=Meena, marks=88]]
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=== Q34 Fail-fast iterators and ConcurrentModificationException ===
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removing 2 inside for-each -> ConcurrentModificationException
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removing the second-to-last element threw nothing, list = [1, 2, 4]
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removeIf even -> [1, 3, 5]
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=== Q35 Arrays.asList() and List.of() pitfalls ===
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write-through to the array: changed
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Arrays.asList().add -> UnsupportedOperationException
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Arrays.asList(int[]) has 1 element
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List.of(.., null) -> NullPointerException
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=== Q36 Queue, Deque and PriorityQueue ===
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PriorityQueue polls: 1 2 3 4 5
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ArrayDeque as a stack pops: cba
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=== Q37 Mutable keys and the equals()/hashCode() contract in a HashMap ===
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get with the mutated key: null
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get with a fresh "A1" key: null
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size is still 1
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=== Q38 unmodifiableList() view vs List.copyOf() snapshot ===
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view sees the change: [a, b, c]
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copy does not: [a, b]
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