PriorityQueue

title: PriorityQueue in Java description: Priority based ordering queue

Elements priority ke hisaab se nikalta hai — by default min-heap (smallest first).

Create karna

java exampleWoHoTech

PriorityQueue<Integer> pq = new PriorityQueue<>();            // Min-heap
PriorityQueue<Integer> maxPQ = new PriorityQueue<>(Collections.reverseOrder()); // Max-heap

Operations

java exampleWoHoTech

PriorityQueue<Integer> pq = new PriorityQueue<>();
pq.offer(30);
pq.offer(10);
pq.offer(20);

pq.peek();    // 10 (smallest, not removed)
pq.poll();    // 10 (removed)
pq.poll();    // 20
pq.poll();    // 30

pq.size();
pq.isEmpty();
pq.contains(20);

Custom Priority (Comparator)

// Task priority — higher number = higher priority PriorityQueue<int[]> pq = new PriorityQueue<>((a, b) -> b[1] - a[1]); pq.offer(new int[]{1, 5}); // task 1, priority 5 pq.offer(new int[]{2, 10}); // task 2, priority 10 pq.offer(new int[]{3, 1}); // task 3, priority 1 int[] task = pq.poll(); // task 2 (priority 10 — highest)

String Priority Queue

java exampleWoHoTech

PriorityQueue<String> pq = new PriorityQueue<>();
pq.offer("Banana");
pq.offer("Apple");
pq.offer("Mango");
// Alphabetical order mein nikalega
while (!pq.isEmpty()) System.out.println(pq.poll());
// Apple, Banana, Mango

Use Cases

Task scheduling
Dijkstra's algorithm
Huffman coding
Top K elements

title: PriorityQueue in Java description: Priority based ordering queue

Elements priority ke hisaab se nikalta hai — by default min-heap (smallest first).

Create karna

java exampleWoHoTech

PriorityQueue<Integer> pq = new PriorityQueue<>();            // Min-heap
PriorityQueue<Integer> maxPQ = new PriorityQueue<>(Collections.reverseOrder()); // Max-heap

Operations

java exampleWoHoTech

PriorityQueue<Integer> pq = new PriorityQueue<>();
pq.offer(30);
pq.offer(10);
pq.offer(20);

pq.peek();    // 10 (smallest, not removed)
pq.poll();    // 10 (removed)
pq.poll();    // 20
pq.poll();    // 30

pq.size();
pq.isEmpty();
pq.contains(20);

Custom Priority (Comparator)

String Priority Queue

java exampleWoHoTech

PriorityQueue<String> pq = new PriorityQueue<>();
pq.offer("Banana");
pq.offer("Apple");
pq.offer("Mango");
// Alphabetical order mein nikalega
while (!pq.isEmpty()) System.out.println(pq.poll());
// Apple, Banana, Mango

Use Cases

Task scheduling
Dijkstra's algorithm
Huffman coding
Top K elements

PriorityQueue

Create karna

Operations

Custom Priority (Comparator)

String Priority Queue

Use Cases

Continue learning this concept

PriorityQueue

Create karna

Operations

Custom Priority (Comparator)

String Priority Queue

Use Cases

Continue learning this concept