// enumerations/Tanks.java

// (c)2021 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.

// {NewFeature} Preview in JDK 17

// Compile with javac flags:

// --enable-preview --source 17

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

import java.util.*;

enum Type { TOXIC, FLAMMABLE, NEUTRAL }

record Level(int percent) {

Level {

if(percent < 0 || percent > 100)

throw new IndexOutOfBoundsException(

percent + " percent");

}

}

record Tank(Type type, Level level) {}

public class Tanks {

static String check(Tank tank) {

return switch(tank) {

case Tank t && t.type() == Type.TOXIC

-> "Toxic: " + t;

case Tank t && ( // [1]

t.type() == Type.TOXIC &&

t.level().percent() < 50

) -> "Toxic, low: " + t;

case Tank t && t.type() == Type.FLAMMABLE

-> "Flammable: " + t;

// Equivalent to "default":

case Tank t -> "Other Tank: " + t;

};

}

public static void main(String[] args) {

List.of(

new Tank(Type.TOXIC, new Level(49)),

new Tank(Type.FLAMMABLE, new Level(52)),

new Tank(Type.NEUTRAL, new Level(75))

).forEach(

t -> System.out.println(check(t))

);

}

}