To use a contrived example in Java, here's the code:
enum Commands{
Save("S");
File("F");
private String shortCut;
private Commands(String shortCut){ this.shortCut = shortCut; }
public String getShortCut(){ return shortCut; }
}
I have the following test/driver code:
public static void main(String args[]){
System.out.println(Commands.Save.getShortCut());
}
The question is:
In Java, when is the constructor for an enumerated constant invoked? In the above example, I am only using the Save enumerated constant. Does this mean that the constructor is called once to create Save only? Or will both Save and File be constructed together regardless?
The constructors are invoked when the enum class is initialized. Each constructor will be invoked, in member declaration order, regardless of which members are actually referenced and used.
Much like the static() {...} method, the constructors are invoked when the Enum class is first initialized. All instances of the Enum are created before any may be used.
public static void main(String args[]){
System.out.println(Commands.Save.getShortCut());
}
In this sample, the ctor for both Save and File will have completed before Save.getShortCut() is invoked.
They are invoked sequentially, as declared in the code.
Both will be created at the class initialization time as others said. I like to point out that this is done before any static initializers so you can use these enums in static block.
