举一反三
- E类中System.out.println的输出结果是__________、________________。interface Com{int add(int a,int b);}abstract class A{abstract int add(int a,int b);}class B extends A implements Com{public int add(int a,int b){return a+b;}}public class E{public static void main(String args[ ]){B b=new B();Com com=b;System.out.println(com.add(12,6));A a=b;System.out.println(a.add(10,5));}}
- 阅读程序题(给出【代码】注释标注的代码的输出结果)interface Com {int add( int a, int b);}abstract class People {abstract int add( int a, int b);}class Student extends People implements Com{public int add(int a,int b) {return a + b;}}public class 习题5_阅读3 {public static void main(String args[ ]) {Student stu = new Student ();Com com = stu;int m = com.add(12,6);People p = stu;int n = p.add(12,8);System.out.printf("%d:%d",m,n); //【代码】}}
- 下列代码的输出结果是（ ）interface Com{ int M=100; int on();}class A implements Com{ public int on(){ return Com.M; }}public class E{ public static void main(String args[]){ Com com=new A(); int m=com.on(); System.out.println(m); }}
- 阅读程序题(给出【代码】注释标注的代码的输出结果)interface Com {int add(int a, int b);public static int get(int n){return n;}public default int see( int n){return n;}public default int look( int n) {return n;}}class A implements Com{public int add( int a, int b) { return a + b;}public int see(int n){ return n + 1;}}public class 习题5_阅读4{public static void main( String args[ ]) {A a = new A();int m = a.add(12,6);int n = Com.get( 12);int t = a.see(6);int q = a.look(6);System.out.printf("%d:%d:%d:%d",m,n, t,q); //【代码】 }}}
- 说出下列B类中【代码1】，【代码2】的输出结果 class A { public int getNumber(int a) { return a+1; } } class B extends A { public int getNumber (int a) { return a+100; } public static void main (String args[]) { A a =new A(); System.out.println(a.getNumber(10)); //【代码1】 a = new B(); System.out.println(a.getNumber(10)); //【代码2】 } }
内容
- 0
public class test1 { public static int add(int a, int b) { return a+b; } public static double add(double a, double b) { return a+b; } ________________ ___________________ { ________________ ___________________ } public static void main(String[] args) { System.out.println("调用add方法:"+add(2.1,3.4,4.5)); } }
- 1
给出下列【代码】注释标注的代码的输出结果。abstract class A {abstract int get(int a,int b);}public class E {public static void main(String args[]) {A a=new A() {public int get(int a,int b){return a+b;}};int m = a.get(2,5);a=new A() {public int get(int a,int b){return a*b;}};int n = a.get(2,5);System.out.printf("%d:%d",m,n);//【代码】}}
- 2
关于下列代码说法正确的是( ) public class Foo{ public int add(int a,int b){ return a+b; } public static void main(String[] args){ Foo foo = null; System.out.println(foo.add(10,20)); } }
- 3
请写出下列程序的输出结果。class A{public int f(int x) {return x+1;}}class B extends A{public int f(int x){return x*x;}}public class E{public static void main(String args[]){A a=new B();int m=a.f(10);System. out. println(m) ;}}
- 4
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】 } }