In this post, we will learn java set to array conversion.
Table of Contents
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]
