Java Enum在switch语句上

Question

I have this piece of code right here , I really don't get it why is that there is a "this" keyword in the switch statement, take a look at this code

public enum InstrumentType{

    GUITAR,BANJO,MANDOLIN,DOBRO, FIDDLE ,BASS,

    public String toString(){
        switch(this){
        case GUITAR:
            return "Guitar";
        case BANJO: 
            return "Banjo";
        case DOBRO:
            return "Dobro";
        case FIDDLE:
            return "Fiddle";
        case BASS:
            return "Bass";
        case MANDOLIN:
            return "Mandolin";
        default: 
            return "Unspecified";
        }
    }
}

Answer 1

Here this refers to the current InstrumentType value

static void MyFunc( )
{
    InstrumentType f = InstrumentType.GUITAR;
    String s = f.toString();
}

When f.toString() is invoked. this will have GUITAR value

Answer 2

It refers to the current instance.

If you had an anum instance "foo":

String s = foo.toString();

Answer 3

this points to its container class/struct/enum like elements. in this case, this is used for InstrumentType . it's a basic rule for most of the OO languages.