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Set toArray() method in Java with Example

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  • Last Updated : 24 Aug, 2021

The toArray() method of Java Set is used to form an array of the same elements as that of the Set. Basically, it copies all the element from a Set to a new array.
Syntax: 
 

Object[] toArray()

Parameters: The method takes optional parameter. If we provide the type of Object array we want we can pass it as an argument. for ex: set.toArray(new Integer[0]) returns an array of type Integer, we can also do it as set.toArray(new Integer[size]) where size is the size of the resultant array. Doing it in the former way works as the required size is allocated internally. 
Return Value: The method returns an array containing the elements similar to the Set.
Below programs illustrate the Set.toArray() method:
Program 1:
 

Java




// Java code to illustrate toArray()
 
import java.util.*;
 
public class SetDemo {
    public static void main(String args[])
    {
        // Creating an empty Set
        Set<String> abs_col = new HashSet<String>();
 
        // Use add() method to add
        // elements into the Set
        abs_col.add("Welcome");
        abs_col.add("To");
        abs_col.add("Geeks");
        abs_col.add("For");
        abs_col.add("Geeks");
 
        // Displaying the Set
        System.out.println("The Set: "
                           + abs_col);
 
        // Creating the array and using toArray()
        Object[] arr = abs_col.toArray();
 
        System.out.println("The array is:");
        for (int j = 0; j < arr.length; j++)
            System.out.println(arr[j]);
    }
}

Output: 

The Set: [Geeks, For, Welcome, To]
The array is:
Geeks
For
Welcome
To

 

Program 2:
 

Java




// Java code to illustrate toArray()
 
import java.util.*;
 
public class SetDemo {
    public static void main(String args[])
    {
        // Creating an empty Set
        Set<Integer> abs_col = new HashSet<Integer>();
 
        // Use add() method to add
        // elements into the Set
        abs_col.add(10);
        abs_col.add(15);
        abs_col.add(30);
        abs_col.add(20);
        abs_col.add(5);
        abs_col.add(25);
 
        // Displaying the Set
        System.out.println("The Set: " + abs_col);
 
        // Creating the array and using toArray()
        Integer[] arr = abs_col.toArray(new Integer[0]);
 
        System.out.println("The array is:");
        for (int j = 0; j < arr.length; j++)
            System.out.println(arr[j]);
    }
}

Output: 

The Set: [20, 5, 25, 10, 30, 15]
The array is:
20
5
25
10
30
15

 

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#toArray()
 


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