The toArray() method of DelayQueue is used to return an array containing all the elements in DelayQueue. There elements are not in any specific order in the array.
Syntax:
public Object[] toArray ()
or
public T[] toArray (T[] a)
Parameters: This method either accepts no parameters or it takes an array T[] a as parameter which is the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
Return Value: The function returns an array containing all the elements in this list.
Exception: The first overload of this method throws no exceptions. However, the second overload throws following exceptions:
- ArrayStoreException: if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue.
- NullPointerException: if the specified array is null.
Below programs illustrate the DelayQueue.toArray() method:
Program 1:
Java
// Java Program Demonstrate DelayQueue toArray() methodimport java.util.concurrent.*;import java.util.*;// The DelayObject for DelayQueue// It must implement Delayed and// its getDelay() and compareTo() methodclass DelayObject implements Delayed { private String name; private long time; // Constructor of DelayObject public DelayObject(String name, long delayTime) { this.name = name; this.time = System.currentTimeMillis() + delayTime; } // Implementing getDelay() method of Delayed @Override public long getDelay(TimeUnit unit) { long diff = time - System.currentTimeMillis(); return unit.convert(diff, TimeUnit.MILLISECONDS); } // Implementing compareTo() method of Delayed @Override public int compareTo(Delayed obj) { if (this.time < ((DelayObject)obj).time) { return -1; } if (this.time > ((DelayObject)obj).time) { return 1; } return 0; } // Implementing toString() method of Delayed @Override public String toString() { return "\n{" + " " + name + ", time=" + time + "}"; }}// Driver Classpublic class GFG { public static void main(String[] args) throws InterruptedException { // create object of DelayQueue // using DelayQueue() constructor BlockingQueue<DelayObject> DQ = new DelayQueue<DelayObject>(); // Add numbers to end of DelayQueue // using add() method DQ.add(new DelayObject("A", 1)); DQ.add(new DelayObject("B", 2)); DQ.add(new DelayObject("C", 3)); DQ.add(new DelayObject("D", 4)); // print queue System.out.println("DelayQueue: " + DQ); // Get the array of the elements // of the ArrayList // using toArray() method Object[] arr = DQ.toArray(); // print the array elements System.out.println("Elements of DelayQueue" + " as Array: " + Arrays.toString(arr)); }} |
Output:
DelayQueue: [
{ A, time=1546842694862},
{ B, time=1546842694863},
{ C, time=1546842694864},
{ D, time=1546842694865}]
Elements of DelayQueue as Array: [
{ A, time=1546842694862},
{ B, time=1546842694863},
{ C, time=1546842694864},
{ D, time=1546842694865}]
Program 2:
Java
// Java Program Demonstrate DelayQueue toArray() methodimport java.util.concurrent.*;import java.util.*;// The DelayObject for DelayQueue// It must implement Delayed and// its getDelay() and compareTo() methodclass DelayObject implements Delayed { private String name; private long time; // Constructor of DelayObject public DelayObject(String name, long delayTime) { this.name = name; this.time = System.currentTimeMillis() + delayTime; } // Implementing getDelay() method of Delayed @Override public long getDelay(TimeUnit unit) { long diff = time - System.currentTimeMillis(); return unit.convert(diff, TimeUnit.MILLISECONDS); } // Implementing compareTo() method of Delayed @Override public int compareTo(Delayed obj) { if (this.time < ((DelayObject)obj).time) { return -1; } if (this.time > ((DelayObject)obj).time) { return 1; } return 0; } // Implementing toString() method of Delayed @Override public String toString() { return "\n{" + " " + name + ", time=" + time + "}"; }}// Driver Classpublic class GFG { public static void main(String[] args) throws InterruptedException { // create object of DelayQueue // using DelayQueue() constructor BlockingQueue<DelayObject> DQ = new DelayQueue<DelayObject>(); // Add numbers to end of DelayQueue // using add() method DQ.add(new DelayObject("A", 1)); DQ.add(new DelayObject("B", 2)); DQ.add(new DelayObject("C", 3)); DQ.add(new DelayObject("D", 4)); // print queue System.out.println("DelayQueue: " + DQ); // Get the array of the elements // of the DelayQueue // using toArray(T[]) method Delayed arr[] = new Delayed[DQ.size()]; arr = DQ.toArray(arr); // print the array elements System.out.println("Elements of ArrayList" + " as Array: " + Arrays.toString(arr)); }} |
Output:
DelayQueue: [
{ A, time=1546842699503},
{ B, time=1546842699504},
{ C, time=1546842699505},
{ D, time=1546842699506}]
Elements of ArrayList as Array: [
{ A, time=1546842699503},
{ B, time=1546842699504},
{ C, time=1546842699505},
{ D, time=1546842699506}]
