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
A: 15.0,8.0
B: 15.08
C: 158
D: 815
举一反三
- 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()
- 中国大学MOOC:编译并运行下面的程序，运行结果为（ ）。publicclassMain{publicstaticvoidmain(String[]args){AAobj=newBB();System.out.println(obj.f(4,6));}}classAA{doublef(doublex,doubley){returnx*y;}}classBBextendsAA{doublef(doublex,doubley){returnx+y;}}
- 执行下列程序，输出结果为（）。publicclassB{publicstaticvoidmain(String[]args){intx=5;doubley=10.5f;floatz=(float)(x*y);System.out.println(z);}}
- 请说出E类中【代码1】，【代码2】的输出结果。 interface A { double f(double x,double y); } class B implements A { public double f(double x,double y) { return x*y; } int g(int a,int b) { return a+b; } } public class E { public static void main(String args[]) { A a = new B(); System.out.println(a.f(3,5)); //【代码1】 B b = (B)a; System.out.println(b.g(3,5)); //【代码2】 } }
- 中国大学MOOC: 下列代码中构造方法的返回类型是（）public class Village { Village () { System .out .println(“hiding in Village”) ; } public static void main( String args [ ]) { Village c =new Village ( ) ;}class Village { public static void main( String args [ ]) { Village c =new Village ( ) ; } Village () { System .out .println(“hiding in Village”) ; } }