In this post, we will learn java set to array conversion.
Table of Contents
There are many ways to convert set to an array.
1. Using Java 8’s Stream
If you are using Java 8, I would recommend using this method.
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package org.arpit.java2blog; import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class SetToArrayMain { public static void main(String[] args) { // Creating a new HashSet Set<String> s = new HashSet<String>(); s.add("John"); s.add("Martin"); s.add("Mary"); String[] arr = s.stream().toArray(String[] ::new); System.out.println(Arrays.toString(arr)); } } |
Output
[John, Martin, Mary]
2. Using toArray()
We can directly call toArray method on set object for java set to array conversion.
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package org.arpit.java2blog; import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class SetToArrayMain { public static void main(String[] args) { // Creating a new HashSet Set<String> set = new HashSet<String>(); set.add("John"); set.add("Martin"); set.add("Mary"); String array[] = new String[set.size()]; array = set.toArray(array); System.out.println(Arrays.toString(array)); } } |
Output
[John, Martin, Mary]
3. Using System.arraycopy()
We can use System.arraycopy for java set to List conversion.
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package org.arpit.java2blog; import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class SetToArrayMain { public static void main(String[] args) { // Creating a new HashSet Set<String> set = new HashSet<String>(); set.add("John"); set.add("Martin"); set.add("Mary"); String array[] = new String[set.size()]; System.arraycopy(set.toArray(), 0, array, 0, set.size()); System.out.println(Arrays.toString(array)); } } |
Output
[John, Martin, Mary]
4. Using simple iteration
Iterate through set and put the value in array manually.
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package org.arpit.java2blog; import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class SetToArrayMain { public static void main(String[] args) { // Creating a new HashSet Set<String> set = new HashSet<String>(); set.add("John"); set.add("Martin"); set.add("Mary"); String array[] = new String[set.size()]; int i = 0; for (String x : set) { array[i++] = x; } System.out.println(Arrays.toString(array)); } } |
Output
[John, Martin, Mary]
