- 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]);
}
}
chevron_rightfilter_noneOutput:
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]);
}
}
chevron_rightfilter_noneOutput: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[])
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]);
}
}
chevron_rightfilter_noneOutput: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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