java-priority-queue-examples

import java.util.PriorityQueue;

public class CreatePriorityQueueExample {
    public static void main(String[] args) {
        // Create a Priority Queue
        PriorityQueue<Integer> numbers = new PriorityQueue<>();

        // Add items to a Priority Queue (ENQUEUE)
        numbers.add(750);
        numbers.add(500);
        numbers.add(900);
        numbers.add(100);

        // Remove items from the Priority Queue (DEQUEUE)
        while (!numbers.isEmpty()) {
            System.out.println(numbers.remove());
        }

    }
}

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import java.util.PriorityQueue;

public class CreatePriorityQueueStringExample {
    public static void main(String[] args) {
        // Create a Priority Queue
        PriorityQueue<String> namePriorityQueue = new PriorityQueue<>();

        // Add items to a Priority Queue (ENQUEUE)
        namePriorityQueue.add("Lisa");
        namePriorityQueue.add("Robert");
        namePriorityQueue.add("John");
        namePriorityQueue.add("Chris");
        namePriorityQueue.add("Angelina");
        namePriorityQueue.add("Joe");

        // Remove items from the Priority Queue (DEQUEUE)
        while (!namePriorityQueue.isEmpty()) {
            System.out.println(namePriorityQueue.remove());
        }

    }
}

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import java.util.Comparator;
import java.util.PriorityQueue;

public class PriorityQueueCustomComparatorExample {
    public static void main(String[] args) {
        Comparator<String> stringLengthComparator = new Comparator<String>() {
            @Override
            public int compare(String s1, String s2) {
                return s1.length() - s2.length();
            }
        };

        /*
        The above Comparator can also be created using lambda expression like this =>
        Comparator<String> stringLengthComparator = (s1, s2) -> {
            return s1.length() - s2.length();
        };

        The above statement can be shortened even further like this =>
        Comparator<String> stringLengthComparator = Comparator.comparingInt(String::length);
        */

        // Create a Priority Queue with a custom Comparator
        PriorityQueue<String> namePriorityQueue = new PriorityQueue<>(stringLengthComparator);

        // Add items to a Priority Queue (ENQUEUE)
        namePriorityQueue.add("Lisa");
        namePriorityQueue.add("Robert");
        namePriorityQueue.add("John");
        namePriorityQueue.add("Chris");
        namePriorityQueue.add("Angelina");
        namePriorityQueue.add("Joe");

        // Remove items from the Priority Queue (DEQUEUE)
        while (!namePriorityQueue.isEmpty()) {
            System.out.println(namePriorityQueue.remove());
        }
    }
}