![]() ![]() If you use enums instead of integers (or String codes), you increase compile-time checking and avoid errors from passing in invalid constants, and you document which values are legal to use.īetween, overuse of enums might mean that your methods do too much (it’s often better to have several separate methods, rather than one method that takes several flags which modify what it does), but if you have to use flags or type codes, enums are the way to go. Examples would be things like type constants (contract status: “permanent”, “temp”, “apprentice”), or flags (“execute now”, “defer execution”). ![]() You should always use enums when a variable (especially a method parameter) can only take one out of a small set of possible values. This way we can easily create an EnumSet containing all the elements of our Color enum: EnumSet.allOf (Color.class) Likewise, we can use noneOf () to do the opposite and create an empty collection of Color: EnumSet.noneOf (Color. All of the following members are auto-incremented from that point on. The most simple methods to create an EnumSet are allOf () and noneOf (). This request is reviewed by the Team Leader, who escalates it to the Department Manager. Above, we have a numeric enum where Up is initialized with 1. As an example, let’s suppose we have an HR software system that can approve leave requests submitted by employees. This allows for type-safe implementation and more readable code. ![]() When you need a predefined list of values which do represent some kind of numeric or textual data, you should use an enum. A Java Enum is a special type of class that defines a list of constants. For instance, in a chess game you could represent the different types of pieces as an enum: enum ChessPiece Įnums are lists of constants. When you need a predefined list of values which do represent some kind of numeric or textual data, you should use an enum. The Java type system, however, treats enumerations as a type separate from integers, and intermixing of enum and integer values is not allowed. An EnumMap is a compact, efficient, and fast alternative to using a HashMap with enum keys. Have you heard of Final keyword? It’s like that. The EnumMap class in Java is a specialized map implementation that is designed specifically for use with enum keys. A singleton is employed to ensure that only a single instance exists of a given class. Enums are lists of constants like unchangeable variables. One example I use regularly is to employ an enum to implement a singleton pattern. ![]()
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