Return the head of list as or none. - Java java.util

Java examples for java.util:List Operation

  1. HOME
  2. Java
  3. java.util
  4. List Operation

Description

Return the head of list as or none.

Demo Code

/**//from   w w  w.  ja  v  a  2 s . c o  m
 *  Copyright 2009, 2010 The Regents of the University of California
 *  Licensed under the Educational Community License, Version 2.0
 *  (the "License"); you may not use this file except in compliance
 *  with the License. You may obtain a copy of the License at
 *
 *  http://www.osedu.org/licenses/ECL-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an "AS IS"
 *  BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 *  or implied. See the License for the specific language governing
 *  permissions and limitations under the License.
 *
 */
import java.util.List;
import java.util.Optional;

public class Main {
  public static void main(String[] argv) {
    List as = java.util.Arrays.asList("asdf", "java2s.com");
    System.out.println(head(as));
  }

  /**
   * Return the head of list <code>as</code> or <code>none</code>.
   */
  public static <A> Optional<A> head(List<A> as) {
    if (!as.isEmpty())
      return Optional.of(as.get(0));
    return Optional.empty();
  }
}

Related Tutorials