- 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.*;publicclassPriorityQueueDemo {publicstaticvoidmain(String args[]){// Creating an empty PriorityQueuePriorityQueue<String> queue =newPriorityQueue<String>();// Use add() method to add elements into the Queuequeue.add("Welcome");queue.add("To");queue.add("Geeks");queue.add("For");queue.add("Geeks");// Displaying the PriorityQueueSystem.out.println("The PriorityQueue: "+ queue);// Creating the array and using toArray()Object[] arr = queue.toArray();System.out.println("The array is:");for(intj =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()importjava.util.*;publicclassPriorityQueueDemo {publicstaticvoidmain(String args[]){// Creating an empty PriorityQueuePriorityQueue<Integer> queue =newPriorityQueue<Integer>();// Use add() method to add elements into the Queuequeue.add(10);queue.add(15);queue.add(30);queue.add(20);queue.add(5);queue.add(25);// Displaying the PriorityQueueSystem.out.println("The PriorityQueue: "+ queue);// Creating the array and using toArray()Object[] arr = queue.toArray();System.out.println("The array is:");for(intj =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.
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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.*;publicclassPriorityQueueDemo {publicstaticvoidmain(String args[]){// Creating an empty PriorityQueuePriorityQueue<String> queue =newPriorityQueue<String>();// Use add() method to add elements into the Queuequeue.add("Welcome");queue.add("To");queue.add("Geeks");queue.add("For");queue.add("Geeks");// Displaying the PriorityQueueSystem.out.println("The PriorityQueue: "+ queue);// Creating the array and using toArray()String[] arr =newString[5];String[] arr1 = queue.toArray(arr);// Displaying arrSystem.out.println("The arr[] is:");for(intj =0; j < arr.length; j++)System.out.println(arr[j]);// Displaying arr1System.out.println();System.out.println("The arr1[] is:");for(inti =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
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