Dada una lista ( ArrayList o LinkedList ), conviértala en un conjunto ( HashSet o TreeSet ) de strings en Java.
Método 1 (Simple)
Simplemente creamos una lista. Recorremos el conjunto dado y uno por uno agregamos elementos a la lista.
// Java program to demonstrate conversion of
// list to set using simple traversal
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a list of strings
List<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
Set<String> hSet = new HashSet<String>();
for (String x : aList)
hSet.add(x);
System.out.println("Created HashSet is");
for (String x : hSet)
System.out.println(x);
// We can created TreeSet same way
}
}
Método 2 (usando HashSet o TreeSet Constructor)
// Java program to demonstrate conversion of
// list to set using constructor
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a list of strings
List<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
// Creating a hash set using constructor
Set<String> hSet = new HashSet<String>(aList);
System.out.println("Created HashSet is");
for (String x : hSet)
System.out.println(x);
System.out.println("Created TreeSet is");
Set<String> tSet = new TreeSet<String>(aList);
System.out.println("Created TreeSet is");
for (String x : tSet)
System.out.println(x);
}
}
Método 3 (usando el método addAll)
// Java program to demonstrate conversion of
// Set to array using addAll() method.
import java.util.*;
class Test {
public static void main(String[] args)
{
// Creating a list of strings
List<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
Set<String> hSet = new HashSet<String>(aList);
hSet.addAll(aList);
System.out.println("Created HashSet is");
for (String x : hSet)
System.out.println(x);
Set<String> tSet = new TreeSet<String>(aList);
tSet.addAll(aList);
System.out.println("Created TreeSet is");
for (String x : tSet)
System.out.println(x);
}
}
Método 4 (Uso de flujo en Java )
Usamos flujo en Java para convertir una lista dada en flujo, luego flujo en conjunto. Esto funciona solo en Java 8 o versiones posteriores.
// Java program to demonstrate conversion of
// Set to list using stream
import java.util.*;
import java.util.stream.*;
class Test {
public static void main(String[] args)
{
// Creating a list of strings
List<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
// Converting to set using stream
Set<String> set = aList.stream().collect(Collectors.toSet());
for (String x : set)
System.out.println(x);
}
}