PriorityQueue toArray() Method in Java

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  1. The java.util.PriorityQueue.toArray() method in Java is used to form an array of the same elements as that of the Priority Queue. Basically, it copies all the element from a priority queue to a new array.

    Syntax:

    Object[] arr = Priority_Queue.toArray()

    Parameters: The method does not take any parameters.

    Return Value: The method returns an array containing the elements similar to the priority queue.

    Below programs illustrate the java.util.PriorityQueue.toArray() method.
    Program 1:




    // Java code to illustrate toArray()
    import java.util.*;
      
    public class PriorityQueueDemo {
        public static void main(String args[])
        {
            // Creating an empty PriorityQueue
            PriorityQueue<String> queue = new PriorityQueue<String>();
      
            // Use add() method to add elements into the Queue
            queue.add("Welcome");
            queue.add("To");
            queue.add("Geeks");
            queue.add("For");
            queue.add("Geeks");
      
            // Displaying the PriorityQueue
            System.out.println("The PriorityQueue: " + queue);
      
            // Creating the array and using toArray()
            Object[] arr = queue.toArray();
      
            System.out.println("The array is:");
            for (int j = 0; j < arr.length; j++)
                System.out.println(arr[j]);
        }
    }
    		 

    

    

    

    

    

    

    Output:
    

    

    

    The PriorityQueue: [For, Geeks, To, Welcome, Geeks]
The array is:
For
Geeks
To
Welcome
Geeks

    

    

    Program 2:
    

    

    

    

    

    

    


    

    

    

    



    

    

    

    

    

    

    

    


    


    

    // Java code to illustrate toArray()
    

    import java.util.*;
    

      
    

    public class PriorityQueueDemo {
    

        public static void main(String args[])
    

        {
    

            // Creating an empty PriorityQueue
    

            PriorityQueue<Integer> queue = new PriorityQueue<Integer>();
    

      
    

            // Use add() method to add elements into the Queue
    

            queue.add(10);
    

            queue.add(15);
    

            queue.add(30);
    

            queue.add(20);
    

            queue.add(5);
    

            queue.add(25);
    

      
    

            // Displaying the PriorityQueue
    

            System.out.println("The PriorityQueue: " + queue);
    

      
    

            // Creating the array and using toArray()
    

            Object[] arr = queue.toArray();
    

      
    

            System.out.println("The array is:");
    

            for (int j = 0; j < arr.length; j++)
    

                System.out.println(arr[j]);
    

        }
    

    }
    

    
    		

    
    

    

    

    

    

    

    

    

    

    

    

    

    

    

    Output:
    

    

    The PriorityQueue: [5, 10, 25, 20, 15, 30]
The array is:
5
10
25
20
15
30

    

    

    2. 

  2. The java.util.PriorityQueue.toArray(arr[]) method in Java is used to form an array of the same elements as that of the Priority Queue. Basically, it copies all the element from a priority queue to a new array. It creates multiple arrays, unlike the previous method without parameters. This method copies all of the elements into the arr[].
    Syntax:

    Object[] arr1 = Priority_Queue.toArray(arr[])
    

    Parameters: The method accepts one parameter arr[] into which all of the elements of the queue are to be copied.
    

    Return Value: The method returns an array containing the elements similar to the priority queue.
    

      Exception: The method might throw two types of exception:
      

    • ArrayStoreException: When the mentioned array is of the different type and is not able to compare with the elements mentioned in the queue.
      • 

    • NullPointerException: If the array is Null, then this exception is thrown.
      • 

    

    Below program illustrates the working of the java.util.PriorityQueue.toArray(arr[]) method.
    

    

    

    

    

    

    


    

    

    

    



    

    

    

    

    

    

    

    


    


    

    // Java code to illustrate toArray(arr[])
    

    import java.util.*;
    

      
    

    public class PriorityQueueDemo {
    

        public static void main(String args[])
    

        {
    

            // Creating an empty PriorityQueue
    

            PriorityQueue<String> queue = new PriorityQueue<String>();
    

      
    

            // Use add() method to add elements into the Queue
    

            queue.add("Welcome");
    

            queue.add("To");
    

            queue.add("Geeks");
    

            queue.add("For");
    

            queue.add("Geeks");
    

      
    

            // Displaying the PriorityQueue
    

            System.out.println("The PriorityQueue: " + queue);
    

      
    

            // Creating the array and using toArray()
    

            String[] arr = new String[5];
    

            String[] arr1 = queue.toArray(arr);
    

              
    

            // Displaying arr
    

            System.out.println("The arr[] is:");
    

            for (int j = 0; j < arr.length; j++)
    

                System.out.println(arr[j]);
    

              
    

            // Displaying arr1
    

            System.out.println();    
    

            System.out.println("The arr1[] is:");
    

            for (int i = 0; i < arr1.length; i++)
    

                System.out.println(arr1[i]);
    

        }
    

    }
    

    
    		

    
    

    

    

    

    

    

    

    

    

    

    

    

    

    

    Output:
    

    The PriorityQueue: [For, Geeks, To, Welcome, Geeks]
The arr[] is:
For
Geeks
To
Welcome
Geeks

The arr1[] is:
For
Geeks
To
Welcome
Geeks

    

    

    3. 







			
		


				

			

				

						
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