9.3.2

Examples of Field Declarations

INTERFACES

9.3.2   Examples of Field Declarations

The following example illustrates some (possibly subtle) points about field decla 

rations.

9.3.2.1

Ambiguous Inherited Fields

If two fields with the same name are inherited by an interface because, for exam 

ple, two of its direct superinterfaces declare fields with that name, then a single

ambiguous member

 results. Any use of this ambiguous member will result in a

compile time error. Thus in the example:

interface BaseColors {

int RED = 1, GREEN = 2, BLUE = 4;

}

interface RainbowColors extends BaseColors {

int YELLOW = 3, ORANGE = 5, INDIGO = 6, VIOLET = 7;

}

interface PrintColors extends BaseColors {

int YELLOW = 8, CYAN = 16, MAGENTA = 32;

}

interface LotsOfColors extends RainbowColors, PrintColors {

int FUCHSIA = 17, VERMILION = 43, CHARTREUSE = RED+90;

}

the interface

LotsOfColors

 inherits two fields named

YELLOW

. This is all right as

long as the interface does not contain any reference by simple name to the field

YELLOW

. (Such a reference could occur within a variable initializer for a field.)

Even if interface

PrintColors

 were to give the value

3

 to

YELLOW

 rather than

the value

8

, a reference to field

YELLOW

 within interface

LotsOfColors

 would

still be considered ambiguous.

9.3.2.2

Multiply Inherited Fields

If a single field is inherited multiple times from the same interface because, for

example, both this interface and one of this interface's direct superinterfaces

extend the interface that declares the field, then only a single member results. This

situation does not in itself cause a compile time error.

In the example in the previous section, the fields

RED

,

GREEN

, and

BLUE

 are

inherited by interface

LotsOfColors

 in more than one way, through interface

RainbowColors

 and also through interface

PrintColors

, but the reference to

field

RED

 in interface

LotsOfColors

 is not considered ambiguous because only

one actual declaration of the field

RED

 is involved.

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