Java Collection, PriorityQueue Exercises: Retrieve and remove the first element

Java Collection, PriorityQueue Exercises: Exercise-9 with Solution

Write a Java program to retrieve and remove the first element.

Sample Solution:-

Java Code:

import java.util.PriorityQueue;

  public class Exercise9 {
  public static void main(String[] args) {
   // Create Priority Queue
      PriorityQueue<Integer> pq1 = new PriorityQueue<Integer>();  
      PriorityQueue<Integer> pq2 = new PriorityQueue<Integer>();     
   // Add numbers in the Priority Queue
   System.out.println("Original Priority Queue: "+pq1);
   System.out.println("Removes the first element: "+pq1.poll());
   System.out.println("Priority Queue after removing first element: "+pq1);

Sample Output:

Original Priority Queue: [10, 14, 36, 16, 22, 70, 82, 89, 25]          
Removes the first element: 10                                          
Priority Queue after removing first element: [14, 16, 36, 25, 22, 70, 8
2, 89] 

Java Code Editor:

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Java: Tips of the Day

Try and catch:

Java is excellent at catching errors, but it can only recover gracefully if you tell it what to do. The cascading hierarchy of attempting to perform an action in Java starts with try, falls back to catch, and ends with finally. Should the try clause fail, then catch is invoked, and in the end, there's always finally to perform some sensible action regardless of the results. Here's an example:

try {
        cmd = parser.parse(opt, args); 
        if(cmd.hasOption("help")) {
                HelpFormatter helper = new HelpFormatter();
                helper.printHelp("Hello ", opt);
        else {
                if(cmd.hasOption("shell") || cmd.hasOption("s")) {
                String target = cmd.getOptionValue("tgt");
                } // else
        } // fi
} catch (ParseException err) {
        } //catch
        finally {
                new Hello().helloWorld(opt);
        } //finally
} //try

It's a robust system that attempts to avoid irrecoverable errors or, at least, to provide you with the option to give useful feedback to the user. Use it often, and your users will thank you!

Ref: https://red.ht/3EZc9OC