以下（） 接口的定义是正确的。 A: interfaceA{voidprint(){};} B: abstractinterfaceB{voidprint(){};} C: abstractinterfaceCextendsA,B{abstractvoidprint(){};} D: interfaceD{voidprint();}

interfaceA{doublef(doublex,doubley);}classBimplementsA{publicdoublef(doublex,doubley){returnx*y;}intg(inta,intb){returna+b;}}publicclassE{publicstaticvoidmain(Stringargs[]){Aa=newB();System.out.println(a.f(3,5));//【代码1】Bb=(B)a;System.out.println(b.g(3,5));//【代码2】}}代码1输出()代码2输出()

下列程序段运行结果是()interfaceA{doublef(doublex,doubley);}classBimplementsA{publicdoublef(doublex,doubley){returnx*y;}intg(inta,intb){returna+b;}}publicclassE{publicstaticvoidmain(String[]args){Aa=newB();System.out.println(a.f(3,5));Bb=(B)a;System.out.println(b.g(3,5));}} A: 15.0,8.0 B: 15.08 C: 158 D: 815

以下的类(接口)定义中正确的是( ) A: public class A{ private int x; public getX(){ return x; }} B: public abstract class A{ private int x; public abstract int getX(); public int aMethod(){ return 0; }} C: public class A{ private int x; public abstract int getX();} D: public interface interfaceA{ private int x; public int getX(){ return x; }}