Renaming an enum value will still break the database data.column does not need to take the ORDINAL EnumType value since that’s used by default.Removing existing elements from ann Enum will require to shift all entries in case you are using ORDINAL.If we add a new value in the middle or rearrange the enum’s order, we’ll break the existing data model. New enum elements must be added to the end of the list.ORDINAL can use a SMALLINT which is the most compact db option.Database specification for Enum data type // todo.persist the ordinal with persist the String with JPA 2.1 Annotation.You cannot assign anything else other than predefined Enum constants to an Enum variable The value returned by this method may differ from the one returned by the Object.getClass() method for enum constants with constant-specific class bodies.Įnums are POJOs.Two enum constants e1 and e2 are of the same enum type if and only if e1.getDeclaringClass() = e2.getDeclaringClass().GetDeclaringClass() - Returns the Class object corresponding to this enum constant’s enum type. It’s added by the compiler.įor ( Planet p : Planet. It’s not part of Enum’s java documentation. The values() static method of the enum returns an array of all constants that are declared in the enum. Ordinal() – position of the constant within enum type. compareTo() – Enum implements Comparable.toString () – to return constant’s name.hashCode () – because equals is overridden.finalize () – to ensure that constants cannot be finalized.equals () – Returns true if the specified object is equal to this enum constant.This guarantees that enums are never cloned, which is necessary to preserve their “singleton” status. clone () – Throws CloneNotSupportedException.It is designed for use by sophisticated enum-based data structures, such as EnumSet and EnumMap.Its position in its enum declaration, starts from 0.Should use toString to return a more user-friendly name.The name of this enum constant, which is the identifier used to declare it.Protected Enum ( String name, int ordinal ) We can use = to compare enum constants effectively because constants are final and we cannot call an enum’s constructors to create more constants.By defining a finite set of values, the enum is more type safe than constant literal variables like String or int. When anything else other than constants is there, comma-separated constants should be terminated with a semicolon. The Java enum type provides a language-supported way to create and use constant values.We can add fields, constructors and methods to an enum. In plain English, “to enumerate” means to count off or name one by one from a list. Should use Enums any time you need to represent a fixed set of constantsĪn enum type (or enumerated type) is a type whose fields consist of a fixed set of constants.
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