OnJava8-Examples/interfaces/interfaceprocessor/StringProcessor.java

// interfaces/interfaceprocessor/StringProcessor.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// {java interfaces.interfaceprocessor.StringProcessor}
package interfaces.interfaceprocessor;
import java.util.*;

interface StringProcessor extends Processor {
  @Override
  String process(Object input);  // [1]
  String S = // [2]
  "If she weighs the same as a duck, " +
  "she's made of wood";
  static void main(String[] args) { // [3]
    Applicator.apply(new Upcase(), S);
    Applicator.apply(new Downcase(), S);
    Applicator.apply(new Splitter(), S);
  }
}

class Upcase implements StringProcessor {
  @Override // Covariant return:
  public String process(Object input) {
    return ((String)input).toUpperCase();
  }
}

class Downcase implements StringProcessor {
  @Override
  public String process(Object input) {
    return ((String)input).toLowerCase();
  }
}

class Splitter implements StringProcessor {
  @Override
  public String process(Object input) {
    return Arrays.toString(((String)input).split(" "));
  }
}
/* Output:
Using Processor Upcase
IF SHE WEIGHS THE SAME AS A DUCK, SHE'S MADE OF WOOD
Using Processor Downcase
if she weighs the same as a duck, she's made of wood
Using Processor Splitter
[If, she, weighs, the, same, as, a, duck,, she's, made,
of, wood]
*/