38 lines
1.0 KiB
Java
38 lines
1.0 KiB
Java
// enums/EnumMaps.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Basics of EnumMaps
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// {java enums.EnumMaps}
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package enums;
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import java.util.*;
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import static enums.AlarmPoints.*;
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interface Command { void action(); }
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public class EnumMaps {
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public static void main(String[] args) {
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EnumMap<AlarmPoints,Command> em =
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new EnumMap<>(AlarmPoints.class);
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em.put(KITCHEN,
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() -> System.out.println("Kitchen fire!"));
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em.put(BATHROOM,
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() -> System.out.println("Bathroom alert!"));
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for(Map.Entry<AlarmPoints,Command> e:
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em.entrySet()) {
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System.out.print(e.getKey() + ": ");
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e.getValue().action();
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}
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try { // If there's no value for a particular key:
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em.get(UTILITY).action();
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} catch(Exception e) {
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System.out.println("Expected: " + e);
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}
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}
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}
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/* Output:
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BATHROOM: Bathroom alert!
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KITCHEN: Kitchen fire!
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Expected: java.lang.NullPointerException
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*/
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