PriorityQueue toArray() Method in Java
Last Updated :
10 Dec, 2018
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- 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 // 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:Program 2:The PriorityQueue: [For, Geeks, To, Welcome, Geeks] The array is: For Geeks To Welcome Geeks
Java // 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
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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.
Java // 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
