登陆题目详情
单选题 设B是类,C和D是接口,以下声明正确的是( )
学科：JAVA编程技术
时间：2024-12-17 15:56:19
相关题目
相关作业
题目1单选题
1. public class SimpleCalc{ 2. public int value; 3. public void calculate(){value += 7;} 4. } And: 1. public class MultiCalc extends SimpleCalc{ 2. public void calculate(){value -= 3;} 3. public void calculate(int multiplier){ 4. calculate(); 5. super.calculate(); 6. value *= multiplier; 7. } 8. public static void main(String[] args){ 9. MultiCalc calculator = new MultiCalc(); 10. calculator.calculate(2); 11. System.out.println("Value is: " + calculator.value); 12. } 13. } What is the resultA. 12B. 8C. -12D. Compilation fails
题目2单选题
下面接口声明1-7中,用法错误有几个( ) public interface A { 1. int var=1; 2. public A() { } 3. void method1() { } 4. protected void method2(); 5. static void method3(); 6. static void method4() { } 7. default void method5() { } }A. 3B. 5C. 4D. 6
题目3单选题
10. interface Foo{ } 11. class Alpha implements Foo{ } 12. class Beta extends Alpha{ } 13. class Delta extends Beta{ 14. public static void main(String[ ] args){ 15. Beta x = new Beta(); 16. //insert code here 17. } 18. } Which code, inserted at line 16, will cause a java.lang.ClassCastExceptionA. Foo f = (Delta)xB. Foo f = (Alpha)xC. Beta b = (Beta)(Alpha)xD. Alpha a = x
题目4单选题
B是一个抽象类,C是B的非抽象子类,下列创建对象x的语句中正确的是( )A. B b= new C( )B. C x= new B( )C. B b= new B( )D. C x= C( )
题目5单选题
11.public interface A {12. public static final int EASY = 3;13. void doStuff(int t);14.}15.16.public class Test implements A {17. void doStuff(int s) {18. s += A.EASY + ++s;19. System.out.println("s " + s);20. }21. public static void main(String[] args) {22. int x = 5;23. new Test2().doStuff(++x);24. }35.}What is the resultA. Compilation failsB. s 16C. s 10D. s 14
题目6单选题
下面程序运行结果( ) public class Alpha{ public void foo(){ System.out.print("A"); } } public class Beta extends Alpha{ public void foo(){ System.out.print("B"); } } public class test{ public static void main(String[] args){ Alpha a = new Beta(); Beta b = (Beta)a; a.foo(); b.foo(); }}A. BAB. BBC. ABD. AA
题目7单选题
11. class Alpha{ 12. public void foo(){System.out.print("A");} 13. } 14. public class Beta extends Alpha{ 15. public void foo(){System.out.print("B");} 16. public static void main(String[ ] args){ 17. Alpha a = new Beta(); 18. Beta b = (Beta)a; 19. a.foo(); 20. b.foo(); 21. } 22. } What is the resultA. BAB. BBC. AAD. AB
题目8单选题
设B是类,C和D是接口,以下声明正确的是( )A. public interface A implements C extends B { }B. public interface A extends B { }C. public class A implements C extends B { }D. public class A extends B implements C, D { }
题目9单选题
1. interface TestA{ String toString(); } 2. public class Test{ 3. public static void main(String[ ] args){ 4. System.out.println(new TestA(){ 5. public String toString(){return "test";} 6. }); 7. } 8. } What is the resultA. Compilation fails because of an error in line 5B. Compilation fails because of an error in line 4C. testD. null
题目10单选题
11. public interface A{ public void m1(); } 13. class B implements A{ } 14. class C implements A{ public void m1(){ }} 15. class D implements A{ public void m1(int x){ }} 16. abstract class E implements A { } 17. abstract class F implements A { public void m1(){ } } 18. abstract class G implements A { public void m1(int x){ } } What is the resultA. Exactly one class does NOT compileB. Exactly four class does NOT compileC. Exactly three class does NOT compileD. Exactly two class does NOT compile
下载 题海APP
拍照搜题更快捷
- 海量题库
- 无搜索限制
- 快捷拍照搜题
