How to Declare Enum in Java

1. Purpose of Enums in Java
2. an int Is Required
3. No int Required

Declaring an enum for a DownloadType in Java will be the topic of discussion in this article. Let’s start by looking at the purpose of enums.

Purpose of Enums in Java

1. Enumerations are used so that a collection of objects may be maintained as constants inside a program without the need to depend on an external value, such as an integer.
2. In Java, enums may be used as input on switch statements, and they can be compared securely using the == or equality operator, among other comparison methods.

Because enums are essentially objects of their type and not primitives, you can’t get around having to call a method or use a .value to extract the value from an enum if you need to do so.

To begin, we have to ask ourselves whether or not an int is required. Then there will be two possible outcomes, which we will go through in the following section.

an int Is Required

When you want an integer, you are willing to risk the loss of type safety and the possibility that users would send invalid information to your API. You can declare the below constants as integers as well.

Make the constructor private when you only have static members and wish to simulate a static class in Java.

public final class DownloadType {
  public static final int audio = 0;
  public static final int video = 1;
  public static final int audio_and_video = 2;
  private DownloadType() {}
}

Since the .ordinal() function is available regardless of whether the value field is present, the enum might be defined as:

enum DownloadType { audio, video, audio_and_video }

To get the matching number for an enum value, use the .ordinal() function. Each enumerated value is automatically allocated a unique number beginning with zero and increasing by one for each successive value in the same sequence as declared.

DownloadType.audio_and_video.ordinal();

No int Required

The integer value of an enum isn’t always reliable. Use the value itself instead.

In cases when an associated integer is unnecessary, try this instead:

private enum DownloadType { audio, video, audio_and_video }
DownloadType dt = MyObj.getDownloadType();
if (dt == DownloadType.audio) {
}

You can write your logic in the switch and if() body to perform actions. Further, you can use the switch statement instead of the if() condition.

private enum DownloadType { audio, video, audio_and_video }
DownloadType dt = MyObj.getDownloadType();

switch (dt) {
  case audio:
    break;
  case video:
    break;
  case audio_and_video:
    break;
}

Good Practices

1. You will compromise your program’s type-safety if you use integer constants instead of enumeration constants. Therefore try to avoid doing so.
2. When you don’t necessarily have to, avoid combining an integer with an enum in your code.