TreeSet

title: TreeSet in Java description: TreeSet - sorted unique elements

Sorted order mein unique elements. Internally Red-Black tree (TreeMap) use karta hai.

Create karna

java exampleWoHoTech

TreeSet<Integer> ts = new TreeSet<>();
TreeSet<String> ts2 = new TreeSet<>(Comparator.reverseOrder());

Operations

java exampleWoHoTech

TreeSet<Integer> ts = new TreeSet<>();
ts.add(30); ts.add(10); ts.add(20); ts.add(50); ts.add(40);

// Iteration — sorted order
for (int n : ts) System.out.print(n + " "); // 10 20 30 40 50

// Navigation methods
ts.first();          // 10 (smallest)
ts.last();           // 50 (largest)
ts.higher(20);       // 30 (next greater)
ts.lower(30);        // 20 (next smaller)
ts.ceiling(25);      // 30 (>=25)
ts.floor(25);        // 20 (<=25)
ts.headSet(30);      // {10, 20} (less than 30)
ts.tailSet(30);      // {30, 40, 50} (>=30)
ts.subSet(20, 40);   // {20, 30} (20 to 39)

// Poll
ts.pollFirst();      // Remove and return smallest
ts.pollLast();       // Remove and return largest

Custom Sort

java exampleWoHoTech

TreeSet<String> names = new TreeSet<>(Comparator.comparingInt(String::length));
names.add("Ram");
names.add("Shyam");
names.add("Geeta");
// Sorted by length

Null Nahi Allowed

java exampleWoHoTech

TreeSet<String> ts = new TreeSet<>();
ts.add(null); // NullPointerException!

title: TreeSet in Java description: TreeSet - sorted unique elements

Sorted order mein unique elements. Internally Red-Black tree (TreeMap) use karta hai.

Create karna

java exampleWoHoTech

TreeSet<Integer> ts = new TreeSet<>();
TreeSet<String> ts2 = new TreeSet<>(Comparator.reverseOrder());

Operations

java exampleWoHoTech

TreeSet<Integer> ts = new TreeSet<>();
ts.add(30); ts.add(10); ts.add(20); ts.add(50); ts.add(40);

// Iteration — sorted order
for (int n : ts) System.out.print(n + " "); // 10 20 30 40 50

// Navigation methods
ts.first();          // 10 (smallest)
ts.last();           // 50 (largest)
ts.higher(20);       // 30 (next greater)
ts.lower(30);        // 20 (next smaller)
ts.ceiling(25);      // 30 (>=25)
ts.floor(25);        // 20 (<=25)
ts.headSet(30);      // {10, 20} (less than 30)
ts.tailSet(30);      // {30, 40, 50} (>=30)
ts.subSet(20, 40);   // {20, 30} (20 to 39)

// Poll
ts.pollFirst();      // Remove and return smallest
ts.pollLast();       // Remove and return largest

Custom Sort

java exampleWoHoTech

TreeSet<String> names = new TreeSet<>(Comparator.comparingInt(String::length));
names.add("Ram");
names.add("Shyam");
names.add("Geeta");
// Sorted by length

Null Nahi Allowed

java exampleWoHoTech

TreeSet<String> ts = new TreeSet<>();
ts.add(null); // NullPointerException!

TreeSet

Create karna

Operations

Custom Sort

Null Nahi Allowed

Continue learning this concept

TreeSet

Create karna

Operations

Custom Sort

Null Nahi Allowed

Continue learning this concept