Polymorphism and Interface Methods in Enums Java enums support polymorphism through interface implementation. This means you can treat different enum constants as instances of their common interface type. For i
The above code shows howenum Carsfunctionality is used in theenum DriveCars. Which means the functionality is extended. Thename()method in the above code isfinal, which cannot be overridden, and thevalueOfmethod will be generated by the compiler. Both of these methods are a good fit for eac...
By design, this converter is calledEnum.valueOf(Class, String),which means that the given string must match exactly one of the declared enum constants. For instance, let’s consider theLevelenum: public enum Level { LOW, MEDIUM, HIGH } Next, let’s create ahandler methodthat accepts our ...
However, if we work with the==(equals) operator and compare enum values/objects, it will not throw thenullpointerexception. That means this operator isnullsafe and better to use than theequals()method. See the example below. enumColor{red,green,yello,white,black,purple,blue;}publicclassSimpl...
Adding a new strategy means adding a new implementation class. With enums, we can achieve this with less effort, and adding a new implementation means simply defining another instance with some implementation. The code snippet below shows how to implement the Strategy pattern: ...
Enum is short for "enumerations", which means "specifically listed". 2.4 使用场景 Enums are often used in switch statements to check for corresponding values The enum type has a values() method, which returns an array of all enum constants. ...
1. It returns the Collection view of the values contained in this map. 2. The returned collection obeys the general contract outlined in Map.values(). 3. The collection iterator will return the values in the order of keys in enum map. It means iterator will return the values in the natu...
(in the form of methods) to a typesafe enum. For example, suppose you need to introduce an enum for Canadian coins, and you want the class to provide the means to return the number of nickels, dimes, quarters, or dollars contained in an arbitrary number of pennies. Listing 2 shows you...
Third, there is the fact that Enum is generic in the first place. It means that some of the methods of class Enum take an argument or return a value of an unknown type (or otherwise depend on an unknown type). As we already know, this unknown type will later be a subtype X of En...
It means that all enums arecomparableandserializableimplicitly. Also, all enum types in Java aresingletonby default. As noted all enums extendsjava.lang.Enum, soenum cannot extend any other classbecause Java does not supportmultiple inheritancethis way. But enums can implement any number of inte...