Basic tasks with priority queues in java.

current/algorithms/java/Queue2.java

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+import java.util.*;
+
+public class Program2 {
+
+  public record Element(
+      int weight) implements Comparable {
+
+    public int compareTo(Object o) {
+
+      if (!(o instanceof Element)) {
+        throw new IllegalArgumentException("Got invalid class to compare: " + o.getClass());
+      }
+
+      Element e = (Element)o;
+
+      return weight - e.weight;
+    }
+
+    public String toString() {
+      return "Element{weight = %d}".formatted(weight);
+    }
+  }
+
+  public static void main(String[] args) {
+
+    var pq = new PriorityQueue<Element>();
+    pq.add(new Element(1));
+    pq.add(new Element(5));
+    pq.add(new Element(-3));
+    pq.add(new Element(-7));
+
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+  }
+
+}