Unqualified enum constant java

Unqualified enum constants in switch cases: A requirement in Java? [duplicate]

After adding the statement, you are able to refer to your enumeration members without qualification. This allows you to use the same constant names in different contexts by organizing them in sets of related constants within enumerations. An inquiry arises as to whether the C standard determines the type of enumeration constants before the completion of the enumeration declaration.

Why must enum constants be unqualified in switch cases in java? [duplicate]

Some background information is necessary. The issue concerns the use of qualified enum names in switch cases, such as in the provided example.

switch(methodReturnungMyEnum()) < case MyEnum.A: // . break case MyEnum.B: // . break >

which yields the compiler error

The constant used for an enum switch case label must remain the same.

Indeed, the answer is uncomplicated; my inquiry does not pertain to the exclusion of the MyEnum. section.

Merely out of curiosity, I am questioning the rationale behind this prohibition. It is nearly impossible to ascertain the exact reasoning behind a decision, therefore, I am seeking possible explanations. What distinguishes qualified and unqualified enum constants (or symbols in general)? Additionally, what negative consequences could arise if the compiler were to permit this?

Although many people inquire about resolving the compiler error, there are few who tackle the aforementioned queries.

The actual enumeration type is declared within the switch statement. Subsequently, for each case condition, the compiler simply needs to confirm the presence of the literal in the enumeration.

Including the qualified (such as full qualified) in the case clause would require the compiler to perform an unnecessary check to confirm whether the symbol belongs to the specified enumeration.

This is why simply negating it by saying «not» is not equivalent, even though it may appear so initially.

The restriction’s resolution is provided and elaborated on in this location.

C enumeration declarations, The name of the enumeration constant is used to assign the value. Since the DAY enumeration type was previously declared, only the enumeration tag …

Enumerations and Name Qualification (Visual Basic)

In order to refer to a member of an enumeration, it is important to always specify the enumeration name along with the member name. This means that when you want to refer to Sunday which is a member of your Days enumeration, you should use the following syntax:

Using the Imports Statement

To eliminate the need for fully qualified names, simply include an Imports statement in the namespace declarations section of your code, similar to the given example.

Imports WindowsApplication1.Form1.Days Imports WindowsApplication1.Form1.WorkDays 

The Imports statement allows importing of namespace names from both referenced projects and assemblies, as well as from within the same project where the statement is located. By adding this statement, you can easily refer to your enumeration members without the need for qualification. An example of this is shown below:

To reuse constant names in different contexts, you can group related constants into enumerations. This allows you to utilize the same names for the weekday constants in both the Days and WorkDays enumerations. However, if you choose to use the Imports statement with your enumerations, it is crucial to avoid ambiguous reference s. Take, for instance, the following example:

Imports WindowsApplication1.Form1.Days Imports WindowsApplication1.Form1.WorkDays 

Public Sub New() ' Insert code to implement constructor. X = Monday End Sub 

If Monday is part of both Days and Workdays enumerations, the compiler will generate an error. To avoid this, specify the enumeration when referring to a constant. To demonstrate, the code below references constants from both Saturday in Days and WorkDays enumerations.

X = Days.Saturday Y = WorkDays.Saturday 

• Constants and Enumerations
• How to: Declare an Enumeration
• How to: Refer to an Enumeration Member
• Guide on Navigating an Enumeration in Visual Basic
• A guide on identifying the string connected to an enumeration value.
• When to Use an Enumeration
• Constant and Literal Data Types
• Enum Statement
• Statement for importing (.NET Namespace and Type)
• Data Types

Java — Why do I get an Enum constant reference cannot, The constants names used as operands for the switch’s case branches must be unqualified, so you’ll need to use a static import to achieve that situation in your …

Type of enumeration constants inside enumerator list in C

I’m developing a parser for multi-platform enumeration and stumbled upon an unusual behavior while attempting to address the aforementioned query.

Is the type of enumeration constant determined by the C standard before the completion of the enumeration declaration?

Upon evaluating the size of the enum constants outside the definition, it is observed that all have the size of int, while specifically, SIZE0 is equal to 1, SIZE1 is equal to 1, and SIZE2 is equal to 8.

Considering that int has a size of 4 bytes, wouldn’t it make sense for all of them to be equivalent to sizeof(int)?

This is what I have for Keil C251:

signed int VALUE0 = (signed char)-1; enum< VALUE1 = (signed char)-1 >; enum< VALUE2 = -1 >; printf( "Is VALUE0 equal to VALUE1? ---> %s", VALUE0 == VALUE1 ? "Yes!" : "No!" ); printf( "Is VALUE0 equal to VALUE2? ---> %s", VALUE0 == VALUE2 ? "Yes!" : "No!" ); 

Is VALUE0 equal to VALUE1? ---> No! Is VALUE0 equal to VALUE2? ---> Yes! 

Could the dissimilarity between VALUE0 and VALUE1’s definitions be attributed to a type cast that I may have overlooked? Alternatively, could this be a compiler bug?

In C, an enumeration constant belongs to the int type, unlike in C++. It is permissible to use an enumeration constant prior to the completion of the type declaration.

In case Keil ARMCC is displaying error code sizeof(VAL0) != sizeof (int) , which involves an enumeration constant VAL0 , it means that Keil ARMCC is not a C compiler that adheres to the standards. Several questions asked here also suggest that it is a non-conforming compiler.

It’s not considered a compiler bug to be non-conforming, unless the vendor asserts that it is conforming, which is not the case to the best of my knowledge.

It is expected that most C compilers that conform to standards will assign the constants with MIN_SIGNED_CHAR_ the value -128 , which is of type int . Similarly, the constants with MIN_SIGNED_CHAR__PLUS_1 should be assigned the value -127 , which is also of type int . Although there is a possibility of an implementation with SCHAR_MIN == -127 , it is unlikely and not the case for Keil compiler(s). Therefore, if you are encountering different results, it may be a bug in the compiler.

The definition of MIN_SIGNED_CHAR_3 can be problematic as the conversion process involves multiple steps. Initially, the value -128 is converted to signed char , which results in no change in value. This is then converted to unsigned int , which finally yields UINT_MAX+1-128 (assuming 32 bits, or 4294967168 ). If an enumeration constant has a specified value outside the range of int , it would violate the constraint and require a diagnostic warning. If the program is not rejected by the compiler, the result would be undefined.

Should I explicitly define the values my enumerated, 2 Answers. The identifiers in an enumerator list are declared as constants that have type int and may appear wherever such are permitted. An …

Use Enum for keeping Constants [duplicate]

I know the usage of enum in java.

Is it advisable to employ enums rather than the class mentioned below for holding the program constants?

Using Enum is advised due to several potential reasons.

• Offers built-in methods for traversing immutable values.
• Use the hashtag static functions to retrieve values associated with a specific key.

One can create their own methods to ensure their class is self-sustaining. However, it is recommended to utilize Enum for a more favorable approach.

It’s advisable to employ enums when storing program constants, as you correctly pointed out.

From the given examples, it is evident that this method enables you to:

add/override useful methods for your string literals:

public boolean equalsName(String otherName)

private EnumSet badDays = EnumSet.of(Days.MONDAY, Days.TUESDAY); 

There is a valuable conversation taking place on this topic.

Enum can be utilized as predefined constants, as intended.

The documentation for enumerated types is also referenced similarly.

Enumerated types are unique data types that allow a variable to represent a group of predetermined values.

This works from Java 1.5 and above:

public enum Constants < DB_CF_NAME("agent"), DB_CF_ID("agent_id"), DB_CF_TEXT("agent_text"), DB_CF_LATITUDE("latitude"); private String name; private Constants(String name) < this.name = name; >public String getName() < return name; >> 

The public static final construct is only necessary when programming for Java 1.4 or earlier versions. It is advisable to avoid using it whenever possible.

Use Enumerated Data in Simulink Models, The name of the enumeration class must be unique among data type names and base workspace variable names, and is case-sensitive. Underlying integer values …

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