java constants class vs interface
Do not use Interfaces for constants The most common way to define a constant is in a class and using public static final. The static import feature should always be considered as a replacement for this practice.
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An interface is a reference type in Java.
. That a class uses some constants internally is an implementation detail. An abstract class can have abstract and non-abstract methods. Interface An interface is just like Java Class but it only has static constants and abstract methodJava uses Interface to implement multiple inheritanceA Java class can implement multiple Java Interfaces.
In fact it may even confuse them. It is similar to class. The constant interface pattern is a poor use of interfaces.
It is of no consequence to the users of a class that the class implements a constant interface. If the constant string belongs to the class and you only need the string value keep in the class that uses it Dont use an Interface for situation 1. On a more technical side the Java compiler places the value of the constant into referencing variables in the classes in.
Constants are usually defined in. As mentioned in the link above as Constant Interface Anti-pattern. That a class uses some constants internally is an implementation detail.
Interfaces specify what a class must do and not how. If a class implements such an interface then the class can refer to those constants without a qualifying class name. Java enums constants Share Improve this question edited May 23 2017 at 1144.
An interface can have abstract methods and static constants. One can then use the constant in another class using ClassNameCONSTANT_NAME. It is the same as the final variables.
Along with abstract methods an interface may also contain constants default methods static methods and nested types. This is only a minor advantage. Static imports are introduced in Java 5.
It is the blueprint of the class. It is a collection of abstract methods. Implementing a constant interface causes this implementation detail to leak into the classs exported API.
That a class uses some constants internally is an implementation detail. How do you define and use constants in Java. Implementing a constant interface causes this implementation detail to leak into the classs exported API.
It is of no consequence to the users of a class that the class implements a constant interface. Using static imports you can import static membersproperties of a class so that you can directly access them without prefixing its parent classs name. From Java 8 it can have default and static methods also.
As well the constants used by a class are typically an implementation detail but placing them in an interface promotes them to the public API of the class. In addition to the logistics of maintaining the Constants class itself were also inviting other maintainability problems by encouraging too much interdependency with this one global constants class and various other parts of our application. The constant interface pattern is a poor use of interfaces.
Thanks in advance for thoughts and opinions. So it specifies a set of methods that the class has to implement. Interfaces should only be.
Use Java static imports. A class implements an interface thereby inheriting the abstract methods of the interface. It is of no consequence to the users of a class that the class implements a constant interface.
Implementing a constant interface causes this implementation detail to leak into the classes exported API. An Interface is about capabilities like a Player may be an interface and any class implementing Player must be able to or must implement move. It is of no consequence to the users of a class that the class implements a constant interface.
So we can define a Constants class as shown in first approach above and the use static. Generated on Tue Dec 4 2012 134100 for OpenJDK VM. We can still do better than this.
An abstract class can give complete default code which should be overridden. Its possible to place widely used constants in an interface. We cannot define the method body in the interface.
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