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This article is about how to use enumerations in Java. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Enumerated types (Enumerated Types)

Let's first take a look at the following paragraph of Mini Program:

Enum Day {SUNDAY, MONDAY, TUESDAY

WEDNESDAY, THURSDAY, FRIDAY, SATURDAY}

This declaration provides a user-friendly method of variable definition that enumerates all possible values of this data type, that is, from Monday to Sunday. Regardless of the specific programming language, the core function of enumerations should be:

Type safety (Type Safety)

Compact and efficient enumerated value definition (Compact, Efficient Declaration of Enumerated Values)

Seamless interaction with other parts of the program (Seamless integration with other language features)

High efficiency of operation (Runtime efficiency)

Now let's discuss these characteristics one by one.

1. Type safety

Enumeration creates a new type. It is different from other existing types, including primitive types (integers, floating point numbers, etc.) and other enumerated types in the current scope (Scope). When you assign parameters to a function, integer types and enumerated types are not interchangeable (unless you explicitly cast), and the compiler will enforce this. For example, define such a function with the enumeration declared above:

Public void foo (Day)

If you call this function with an integer, the compiler will give you an error.

Foo (4); / / compilation error

By this standard, then Pascal, Ada, and C++ strictly support enumerations, while the C language is not.

two。 Compact and efficient definition of enumerated values

Defining a giant program should be easy. For example, in Java we have a definition of "quasi-enumeration":

Public static final int SUNDAY = 0

Public static final int MONDAY = 1

Public static final int TUESDAY = 2

Public static final int WEDNESDAY = 3

Public static final int THURSDAY = 4

Public static final int FRIDAY = 5

Public static final int SATURDAY = 6

This definition does not seem concise enough. This is especially important if you have a lot of data to define, and you will feel it more deeply. Although this is not as important as the other three points, we always want the statement to be as concise as possible.

3. Seamless interaction with other parts of the program

Language operators, such as assignment, equality / greater than / less than judgment, should support enumeration. Enumerations should also support array subscripts and operations used in switch/case statements to control the process. For example:

For (Day d = SUNDAY; d

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