Given a set (HashSet or TreeSet) of strings in Java, convert it into an array of strings.
Input : Set hash_Set = new HashSet();
hash_Set.add("Geeks");
hash_Set.add("For");
Output : String arr[] = {"Geeks", "for"}
Method 1 (Simple)
We simply create an empty array. We traverse the given set and one by one add elements to the array.
// Java program to demonstrate conversion of
// Set to array using simple traversal
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
int n = s.size();
String arr[] = new String[n];
int i = 0;
for (String x : s)
arr[i++] = x;
for (String x : arr)
System.out.println(x);
}
}
Geeks for
Method 2 (Using toArray())
// Java program to demonstrate conversion of
// Set to array using toArray()
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
int n = s.size();
String arr[] = new String[n];
// Please refer below post for syntax
// details of toArray()
// https://www.geeksforgeeks.org/arraylist-array-conversion-java-toarray-methods/
arr = s.toArray(arr);
for (String x : arr)
System.out.println(x);
}
}
Geeks for
Method 3 (Using stream in Java)
We use stream in Java to convert given set to steam, then stream to array. This works only in Java 8 or versions after that.
// Java program to demonstrate conversion of
// Set to array using stream
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
int n = s.size();
String[] arr = s.stream().toArray(String[] ::new);
for (String x : arr)
System.out.println(x);
}
}
Geeks for
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