OnJava8-Examples/enumerations/ObjectMatch.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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// enumerations/ObjectMatch.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// {NewFeature} Preview in JDK 17

// Compile with javac flags:

// --enable-preview --source 17

// Run with java flag: --enable-preview

import java.util.*;

record XX() {}

public class ObjectMatch {

static String match(Object o) {

return switch(o) {

case Dog d -> "Walk the dog";

case Fish f -> "Change the fish water";

case Pet sp -> "Not dog or fish";

case String s -> "String " + s;

case Integer i -> "Integer " + i;

case String[] sa -> String.join(", ", sa);

case null, XX xx -> "null or XX: " + xx;

default -> "Something else";

};

}

public static void main(String[] args) {

List.of(new Dog(), new Fish(), new Pet(),

"Oscar", Integer.valueOf(12),

Double.valueOf("47.74"),

new String[]{ "to", "the", "point" },

new XX()

).forEach(

p -> System.out.println(match(p))

);

}

/* Output:

Walk the dog

Change the fish water

Not dog or fish

String Oscar

Integer 12

Something else

to, the, point

null or Object: XX[]

OnJava8-Examples/enumerations/ObjectMatch.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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