Given the code fragment: Map<Integer, String> books = new TreeMap<>(); books.put (1007, "A"); books.put (1001, "B"); books.put (1001, "B"); books.put (1003, "B"); System.out.println (books); What is…

Question

Options

• A{1007 = A, 1002 = C, 1001 = B, 1003 = B}
• B{1001 = B, 1002 = C, 1003 = B, 1007 = A}
• C{1002 = C, 1003 = B, 1007 = A}
• D{1007 = A, 1001 = B, 1003 = B, 1002 = C}

• A
  12% (7)
• B
  78% (46)
• C
  7% (4)
• D
  3% (2)

Explanation

Note: The third put in the code fragment appears to be a typo - it should be books.put(1002, "C") to match the answer choices. The explanation below assumes that correction.

Option B is correct because TreeMap automatically sorts its entries by key in natural ascending order, so regardless of insertion order, the output will be {1001=B, 1002=C, 1003=B, 1007=A}. Also, maps do not allow duplicate keys - if the same key were inserted twice, the second value would simply overwrite the first, keeping only four distinct entries.

Why the distractors are wrong:

• A lists the correct entries but in unsorted (insertion-like) order - TreeMap always sorts, so this is never valid.
• C is missing the 1001=B entry entirely - there are four distinct keys, so four entries must appear.
• D also shows entries in insertion order rather than sorted key order.

Memory tip: Think of TreeMap as a Tidy Map - it always keeps keys Trimmed into sorted order. If you need insertion-order preservation instead, that's LinkedHashMap; if you need no ordering guarantees but raw speed, use HashMap.

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