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TreeMap
Last Updated : 26 May, 2026
title: TreeMap in Java
Collections Framework30 words3 headingsExamples included
title: TreeMap in Java description: TreeMap - sorted key-value store
Keys sorted order mein. Internally Red-Black Tree. NavigableMap implement karta hai.
Create karna
java exampleWoHoTech
TreeMap<String, Integer> tm = new TreeMap<>();
TreeMap<String, Integer> desc = new TreeMap<>(Comparator.reverseOrder());Operations
java exampleWoHoTech
TreeMap<String, Integer> tm = new TreeMap<>();
tm.put("Banana", 3);
tm.put("Apple", 1);
tm.put("Mango", 2);
// Sorted by key
tm.forEach((k, v) -> System.out.println(k + ": " + v));
// Apple: 1, Banana: 3, Mango: 2
// Navigation
tm.firstKey(); // "Apple"
tm.lastKey(); // "Mango"
tm.higherKey("Apple"); // "Banana"
tm.lowerKey("Mango"); // "Banana"
tm.ceilingKey("B"); // "Banana"
tm.floorKey("C"); // "Banana"
// Range views
tm.headMap("Mango"); // Keys < "Mango"
tm.tailMap("Banana"); // Keys >= "Banana"
tm.subMap("Apple", "Mango"); // Apple to Banana
// Poll
tm.pollFirstEntry(); // Remove and return first
tm.pollLastEntry(); // Remove and return lastNull Keys Allowed? No!
java exampleWoHoTech
tm.put(null, 5); // NullPointerExceptionExam Focus
Revise definitions, diagrams, examples, and short-answer points for TreeMap.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
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