Get empty collection from Collections

static List EMPTY_LIST: The empty list (immutable).
static Map EMPTY_MAP: The empty map (immutable).
static Set EMPTY_SET: The empty set (immutable).
static<T> List<T> emptyList(): Returns the empty list (immutable).
static<K,V> Map<K,V> emptyMap(): Returns the empty map (immutable).
static<T> Set<T> emptySet(): Returns the empty set (immutable).


import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Main {
  public static void main(String args[]) {
    List list = Collections.EMPTY_LIST;
    Set set = Collections.EMPTY_SET;
    Map map = Collections.EMPTY_MAP;

    List<String> s = Collections.emptyList();
    Set<Long> l = Collections.emptySet();
    Map<Date, String> d = Collections.emptyMap();
  }
}

 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

class Letters {
  private List<String> letterList;

  Letters() {
    letterList = Collections.emptyList();
  }

  Letters(String... letterName) {
    letterList = new ArrayList<String>();
    for (String name : letterName)
      letterList.add(name);
  }

  @Override
  public String toString() {
    return letterList.toString();
  }
}

public class Main{
  public static void main(String[] args) {
    Letters letters = new Letters();
    System.out.println(letters);
    letters = new Letters("S", "R", "B", "O");
    System.out.println(letters);
  }
}

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