apply.java

来自「Thinking in JAVA第四版源代码」· Java 代码 · 共 52 行

//: interfaces/classprocessor/Apply.java
package interfaces.classprocessor;
import java.util.*;
import static net.mindview.util.Print.*;

class Processor {
  public String name() {
    return getClass().getSimpleName();
  }
  Object process(Object input) { return input; }
}	

class Upcase extends Processor {
  String process(Object input) { // Covariant return
    return ((String)input).toUpperCase();
  }
}

class Downcase extends Processor {
  String process(Object input) {
    return ((String)input).toLowerCase();
  }
}

class Splitter extends Processor {
  String process(Object input) {
    // The split() argument divides a String into pieces:
    return Arrays.toString(((String)input).split(" "));
  }
}	

public class Apply {
  public static void process(Processor p, Object s) {
    print("Using Processor " + p.name());
    print(p.process(s));
  }
  public static String s =
    "Disagreement with beliefs is by definition incorrect";
  public static void main(String[] args) {
    process(new Upcase(), s);
    process(new Downcase(), s);
    process(new Splitter(), s);
  }
} /* Output:
Using Processor Upcase
DISAGREEMENT WITH BELIEFS IS BY DEFINITION INCORRECT
Using Processor Downcase
disagreement with beliefs is by definition incorrect
Using Processor Splitter
[Disagreement, with, beliefs, is, by, definition, incorrect]
*///:~