﻿ Java: Retrieve and remove the first element

# 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

getEnumMap

Converts to enum to Map where key is the name and value is Enum itself.

```public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
return Arrays.stream(enumClass.getEnumConstants())
.collect(Collectors.toMap(Enum::name, Function.identity()));
}
```

Ref: https://bit.ly/3xXcFZt