List.replaceAll(UnaryOperator<E> operator) method in Java

The replaceAll() method of the List interface accept an object of the UnaryOperator representing a particular operation, performs the specified operation on all the elements of the current list and replaces the existing values in the list with their respective results.

Example

 Live Demo

import java.util.ArrayList;
import java.util.function.UnaryOperator;
class Op implements UnaryOperator<String> {
   public String apply(String str) {
      return str.toUpperCase();
   }
}
public class Test {
   public static void main(String[] args) throws CloneNotSupportedException {
      ArrayList<String> list = new ArrayList<>();
      list.add("Java");
      list.add("JavaScript");
      list.add("CoffeeScript");
      list.add("HBase");
      list.add("OpenNLP");
      System.out.println("Contents of the list: "+list);
      list.replaceAll(new Op());
      System.out.println("Contents of the list after replace operation: \n"+list);
   }
}

Output

Contents of the list: [Java, JavaScript, CoffeeScript, HBase, OpenNLP]
Contents of the list after replace operation:[JAVA, JAVASCRIPT, COFFEESCRIPT, HBASE, OPENNLP]