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merged 4 commits into from
Sep 25, 2024
Merged

update enums article #116

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03123b0
update enums article
danthe1st Jun 28, 2024
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address review comments
danthe1st Jul 8, 2024
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add missing space
danthe1st Jul 8, 2024
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Merge branch 'main' into enum-update
ammbra Sep 25, 2024
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20 changes: 11 additions & 9 deletions ...earn/01_tutorial/03_getting-to-know-the-language/04_classes_objects/01_enums.md
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Expand Up @@ -17,7 +17,7 @@ toc:
- Precautions {precautions}
- Conclusion {conclusion}
description: "Working with enums."
last_update: 2023-10-02
last_update: 2024-07-08
author: ["DanielSchmid"]
---
<a id="intro">&nbsp;</a>
Expand All @@ -32,7 +32,7 @@ No instances of the enum can be created outside of enum constants.

```java
public enum DayOfWeek {
// enum constant are listed here:
// enum constants are listed here:
MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
}
```
Expand Down Expand Up @@ -71,11 +71,12 @@ switch (someDay) {
}
```

With [Switch Expressions](id:lang.basics.switch_expressions),
With [switch expressions](id:lang.classes-objects.switch-expression),
the compiler can check whether all values of the enum are handled.
If any possible value is missing in a switch expression, there will be a compiler error.
This is referred to as Exhaustiveness and can also be achieved with regular classes
through [Sealed Classes](jep:409).
This is referred to as exhaustiveness checking and can also be achieved with regular classes
through [sealed classes](https://openjdk.org/jeps/409) and [pattern matching](/learn/pattern-matching/#switch).


```java
DayOfWeek someDay = DayOfWeek.FRIDAY;
Expand All @@ -99,7 +100,8 @@ Arguments to the constructor are passed in parenthesis after the declaration of

```java
public enum DayOfWeek {
MONDAY("MON"), TUESDAY("TUE"), WEDNESDAY("WED"), THURSDAY("THU"), FRIDAY("FRI"), SATURDAY("SAT"), SUNDAY("SUN");
MONDAY("MON"), TUESDAY("TUE"), WEDNESDAY("WED"), THURSDAY("THU"), FRIDAY("FRI"),
SATURDAY("SAT"), SUNDAY("SUN");

private final String abbreviation;

Expand Down Expand Up @@ -140,9 +142,9 @@ This allows for comparing instances of enums as well as sorting or searching.
```java
public void compareDayOfWeek(DayOfWeek dayOfWeek){
int comparison = dayOfWeek.compareTo(DayOfWeek.WEDNESDAY);
if ( comparison < 0) {
if (comparison < 0) {
System.out.println("It's before the middle of the work week.");
} else if(comparison > 0){
} else if (comparison > 0) {
System.out.println("It's after the middle of the work week.");
} else {
System.out.println("It's the middle of the work week.");
Expand Down Expand Up @@ -210,6 +212,6 @@ and reading these configuration files in the program in cases like this.
<a id="conclusion">&nbsp;</a>
## Conclusion

Enums provide a simple and safe way of representing a fixed set of constants while keeping most of the flexibilities of classes. They are a special type of class that can be used to write code that is elegant, readable, and maintainable, and work well with other newer modern features like [Switch Expressions](id:lang.basics.switch_expressions). Another special class is the Record class introduced in Java 19. Visit our [Records tutorial](id:lang.records) to learn more.
Enums provide a simple and safe way of representing a fixed set of constants while keeping most of the flexibilities of classes. They are a special type of class that can be used to write code that is elegant, readable, maintainable and works well with other modern Java features like [switch expressions](id:lang.classes-objects.switch-expression). Another special class is the Record class introduced in Java 19. Visit our [records tutorial](id:lang.records) to learn more.

To learn more about enums, visit the [`java.lang.Enum`](javadoc:Enum) javadoc.