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For example, the duplicate color constants in Drawable and Fillable lead to
access operator, or place these constants in their own interface, and have Drawable
and Fillable extend this interface, as demonstrated in Listing 2-46 .
Listing 2-46. Extending the Colors interface
interface Colors
int RED = 1;
int GREEN = 2;
int BLUE = 3;
int BLACK = 4;
interface Drawable extends Colors
void draw(int color);
interface Fillable extends Colors
void fill(int color);
Thefactthat Drawable and Fillable eachinheritconstantsfrom Colors isnot
aproblemforthecompiler.Thereisonlyasinglecopyoftheseconstants(in Colors )
and no possibility of a name collision, and so the compiler is satisfied.
If a class can implement multiple interfaces by declaring a comma-separated list of
interfacenamesafter implements ,itseemsthataninterfaceshouldbeabletoextend
multiple interfaces in a similar way. This feature is demonstrated in Listing 2-47 .
Listing 2-47. Extending a pair of interfaces
interface A
int X = 1;
interface B
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