- 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()importjava.util.*;ÂÂpublicclassPriorityQueueDemo {   Âpublicstaticvoidmain(String args[])   Â{       Â// Creating an empty PriorityQueue       ÂPriorityQueue<String> queue =newPriorityQueue<String>();       Â// Use add() method to add elements into the Queue       Âqueue.add("Welcome");       Âqueue.add("To");       Âqueue.add("Geeks");       Âqueue.add("For");       Âqueue.add("Geeks");       Â// Displaying the PriorityQueue       ÂSystem.out.println("The PriorityQueue: "+ queue);       Â// Creating the array and using toArray()       ÂObject[] arr = queue.toArray();       ÂSystem.out.println("The array is:");       Âfor(intj =0; j < arr.length; j++)           ÂSystem.out.println(arr[j]);   Â}}Output:The PriorityQueue: [For, Geeks, To, Welcome, Geeks] The array is: For Geeks To Welcome Geeks
Program 2:
// Java code to illustrate toArray()importjava.util.*;ÂÂpublicclassPriorityQueueDemo {   Âpublicstaticvoidmain(String args[])   Â{       Â// Creating an empty PriorityQueue       ÂPriorityQueue<Integer> queue =newPriorityQueue<Integer>();       Â// Use add() method to add elements into the Queue       Âqueue.add(10);       Âqueue.add(15);       Âqueue.add(30);       Âqueue.add(20);       Âqueue.add(5);       Âqueue.add(25);       Â// Displaying the PriorityQueue       ÂSystem.out.println("The PriorityQueue: "+ queue);       Â// Creating the array and using toArray()       ÂObject[] arr = queue.toArray();       ÂSystem.out.println("The array is:");       Âfor(intj =0; j < arr.length; j++)           ÂSystem.out.println(arr[j]);   Â}}Output:The PriorityQueue: [5, 10, 25, 20, 15, 30] The array is: 5 10 25 20 15 30
- 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[])importjava.util.*;ÂÂpublicclassPriorityQueueDemo {   Âpublicstaticvoidmain(String args[])   Â{       Â// Creating an empty PriorityQueue       ÂPriorityQueue<String> queue =newPriorityQueue<String>();       Â// Use add() method to add elements into the Queue       Âqueue.add("Welcome");       Âqueue.add("To");       Âqueue.add("Geeks");       Âqueue.add("For");       Âqueue.add("Geeks");       Â// Displaying the PriorityQueue       ÂSystem.out.println("The PriorityQueue: "+ queue);       Â// Creating the array and using toArray()       ÂString[] arr =newString[5];       ÂString[] arr1 = queue.toArray(arr);        Â       Â// Displaying arr       ÂSystem.out.println("The arr[] is:");       Âfor(intj =0; j < arr.length; j++)           ÂSystem.out.println(arr[j]);        Â       Â// Displaying arr1       ÂSystem.out.println();   Â       ÂSystem.out.println("The arr1[] is:");       Âfor(inti =0; i < arr1.length; i++)           ÂSystem.out.println(arr1[i]);   Â}}Output:The PriorityQueue: [For, Geeks, To, Welcome, Geeks] The arr[] is: For Geeks To Welcome Geeks The arr1[] is: For Geeks To Welcome Geeks
PriorityQueue toArray() Method in Java
