48 lines
1.3 KiB
Java
48 lines
1.3 KiB
Java
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// enumerations/Tanks.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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// {NewFeature} Preview in JDK 17
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// Compile with javac flags:
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// --enable-preview --source 17
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// Run with java flag: --enable-preview
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import java.util.*;
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enum Type { TOXIC, FLAMMABLE, NEUTRAL }
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record Level(int percent) {
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Level {
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if(percent < 0 || percent > 100)
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throw new IndexOutOfBoundsException(
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percent + " percent");
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}
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}
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record Tank(Type type, Level level) {}
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public class Tanks {
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static String check(Tank tank) {
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return switch(tank) {
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case Tank t && t.type() == Type.TOXIC
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-> "Toxic: " + t;
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case Tank t && ( // [1]
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t.type() == Type.TOXIC &&
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t.level().percent() < 50
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) -> "Toxic, low: " + t;
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case Tank t && t.type() == Type.FLAMMABLE
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-> "Flammable: " + t;
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// Equivalent to "default":
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case Tank t -> "Other Tank: " + t;
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};
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}
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public static void main(String[] args) {
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List.of(
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new Tank(Type.TOXIC, new Level(49)),
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new Tank(Type.FLAMMABLE, new Level(52)),
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new Tank(Type.NEUTRAL, new Level(75))
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).forEach(
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t -> System.out.println(check(t))
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);
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}
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}
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