The nested type figure cannot hide an enclosing type

[Birkhoff92]

cerchio

package figureGeometriche;import figureGeometriche.Figura;


publicclassCerchioextendsFigura {


    privatedoubler;
    publicCerchio ( doublex, doubley, doubler) {
        super(x,y);
        this.r=r;
    }
    publicdoubleperimetro() {
        return 2*Math.PI*r;
    }
    publicdoublearea() {
        return Math.PI*r*r;
    }
    
    publicStringtoString() {
        return"Cerchio in ( "+x+" , " +y+" ) di raggio  " +r;
    }
    
    
}