What is an enum class?

An enum class is like a list of predefined options that you can choose from. It helps make your code clearer and safer by limiting the possible choices to a specific set of values. It’s useful when you have a variable that can only have a certain number of options, and you want to make sure it’s always set to one of those options.

How to build one?

a classic enum class with getters

Java

public enum MyEnumClass {

 // Enum constants with values
 A("data A", 1, true),
 B("data B", 1, true),
 C("data C", 1, true);

 // Fields to hold values
 private final String data;
 private final int number;
 private final boolean flag;

 // Constructor to assign values to the fields
 MyEnumClass(String data, int number, boolean flag) {
  this.data = data;
  this.number = number;
  this.flag = flag;
 }

// getters
 public String getData() {
  return data;
 }
 public int getNumber() {
  return number;
 }
 public boolean isFlag() {
  return flag;
 }
}

an enum class with record

Java

public enum MyEnumClassWithRecord {
 D("data D", 1, true),
 E("data E", 1, true),
 F("data F", 1, true);

 // Record class to hold associated values and generate getters
 public record EnumData(String data, int number, boolean flag) {
 }
 // Field to hold the associated EnumData object
 private final EnumData enumData;

 // Constructor to assign values to the EnumData object
 MyEnumClassWithRecord(String data, int number, boolean flag) {
  this.enumData = new EnumData(data, number, flag);
 }
 // Getter method to retrieve the EnumData object
 public EnumData getEnumData() {
  return enumData;
 }
}

To call them, thy both work almost the same way:

Java

MyEnumClass myValue = MyEnumClass.A;
System.out.println(myValue.getData());   // Output: "data A"
System.out.println(myValue.getNumber()); // Output: 1
System.out.println(myValue.isFlag());    // Output: true


MyEnumClassWithRecord myValue = MyEnumClassWithRecord.D;
MyEnumClassWithRecord.EnumData enumData = myValue.getEnumData();
System.out.println(enumData.data());   // Output: "data D"
System.out.println(enumData.number()); // Output: 1
System.out.println(enumData.flag());   // Output: true

In conclusion, if you are using a big list of enums (who would do that, for heaven’s sake?) using the record class is better. If you only have a few constants, the classic way is much cleaner.

Java ENUM with multiple values and record class

What is an enum class?

How to build one?

a classic enum class with getters

an enum class with record

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