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HashSet
Last Updated : 26 May, 2026
title: HashSet in Java
Collections Framework31 words3 headingsExamples included
title: HashSet in Java description: HashSet - unordered unique elements
Unique elements store karta hai. No duplicates, no guaranteed order. Internally HashMap use karta hai.
Create karna
java exampleWoHoTech
HashSet<String> set = new HashSet<>();
HashSet<Integer> set2 = new HashSet<>(16, 0.75f); // capacity, load factorOperations
java exampleWoHoTech
HashSet<String> set = new HashSet<>();
// Add
set.add("Java");
set.add("Python");
set.add("Java"); // Duplicate — ignore hoga
set.addAll(anotherSet);
// Check
set.contains("Java"); // true
set.size(); // 2 (not 3, duplicate removed)
set.isEmpty();
// Remove
set.remove("Python");
set.clear();
// Iteration
for (String s : set) System.out.println(s);
set.forEach(System.out::println);
// Set Operations
Set<Integer> set1 = new HashSet<>(Arrays.asList(1, 2, 3, 4));
Set<Integer> set2 = new HashSet<>(Arrays.asList(3, 4, 5, 6));
// Union
Set<Integer> union = new HashSet<>(set1);
union.addAll(set2); // {1,2,3,4,5,6}
// Intersection
Set<Integer> inter = new HashSet<>(set1);
inter.retainAll(set2); // {3,4}
// Difference
Set<Integer> diff = new HashSet<>(set1);
diff.removeAll(set2); // {1,2}Duplicate Remove karna
java exampleWoHoTech
List<Integer> listWithDups = Arrays.asList(1,2,2,3,3,3,4);
Set<Integer> unique = new HashSet<>(listWithDups); // {1,2,3,4}Exam Focus
Revise definitions, diagrams, examples, and short-answer points for HashSet.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
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