OnJava8-Examples/enumerated/EnumMaps.java

//: enumerated/EnumMaps.java
// Basics of EnumMaps.
package enumerated;
import java.util.*;
import static enumerated.AlarmPoints.*;
import static net.mindview.util.Print.*;

interface Command { void action(); }

public class EnumMaps {
  public static void main(String[] args) {
    EnumMap<AlarmPoints,Command> em =
      new EnumMap<>(AlarmPoints.class);
    em.put(KITCHEN, (Command) () -> {
      print("Kitchen fire!");
    });
    em.put(BATHROOM, (Command) () -> {
      print("Bathroom alert!");
    });
    for(Map.Entry<AlarmPoints,Command> e : em.entrySet()) {
      printnb(e.getKey() + ": ");
      e.getValue().action();
    }
    try { // If there's no value for a particular key:
      em.get(UTILITY).action();
    } catch(Exception e) {
      print("Expected: " + e);
    }
  }
} /* Output:
BATHROOM: Bathroom alert!
KITCHEN: Kitchen fire!
Expected: java.lang.NullPointerException
*///:~