priority queue examples

Author: Rajeev Kumar Singh

java-priority-queue-examples/src/CreatePriorityQueueExample.java

@@ -1,27 +1,9 @@
-import java.util.Comparator;
 import java.util.PriorityQueue;
 
 public class CreatePriorityQueueExample {
     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);
+        // Create a Priority Queue
+        PriorityQueue<String> namePriorityQueue = new PriorityQueue<>();
 
         // Add items to a Priority Queue (ENQUEUE)
         namePriorityQueue.add("Lisa");
@@ -35,5 +17,6 @@ public int compare(String s1, String s2) {
         while (!namePriorityQueue.isEmpty()) {
             System.out.println(namePriorityQueue.remove());
         }
+
     }
 }

java-priority-queue-examples/src/PriorityQueueCustomComparatorExample.java

@@ -0,0 +1,39 @@
+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());
+        }
+    }
+}