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Why is the enum type used in Java?
The Java enum type provides a language-supported way to create and use constant values. By defining a finite set of values, the enum is more type safe than constant literal variables like String or int .
Is the enum value valid in a string?
By defining a finite set of values, the enum is more type safe than constant literal variables like String or int. However, enum values are required to be valid identifiers, and we’re encouraged to use SCREAMING_SNAKE_CASE by convention. Given those limitations, the enum value alone is not suitable for human-readable strings or non-string values.
How is the number stored in an enum treated?
For binary or case-sensitive collations, lettercase is taken into account when assigning values to the column. If you store a number into an ENUM column, the number is treated as the index into the possible values, and the value stored is the enumeration member with that index.
What is the maximum number of elements in an enum column?
For example, a column specified as ENUM (‘Mercury’, ‘Venus’, ‘Earth’) can have any of the values shown here. The index of each value is also shown. An ENUM column can have a maximum of 65,535 distinct elements.
How to get enum in to key value pair in Java?
You could use the values () method on the enum, giving you all possible combinations, and put that in a map using the iterator. I think that the eaiest method for using an Enum as a key in a map is using an EnumMap http://download.oracle.com/javase/1,5.0/docs/api/java/util/EnumMap.html
Which is an example of an enumeration in Java?
Enumerations serve the purpose of representing a group of named constants in a programming language. For example the 4 suits in a deck of playing cards may be 4 enumerators named Club, Diamond, Heart, and Spade, belonging to an enumerated type named Suit.