1. class A {  2. public byte getNumber ()  {  3.   return 1;

题目
单选题
1. class A {  2. public byte getNumber ()  {  3.   return 1;  4.   }  5. }  6.    7. class B extends A {  8. public short getNumber()  {  9.  return 2;  10. }  11.    12. public static void main (String args[]) {   13.    B  b = new B ();  14.      System.out.printIn(b.getNumber())     15.   }  16. }    What is the result?()
A

 Compilation succeeds and 1 is printed.

B

 Compilation succeeds and 2 is printed.

C

 An error at line 8 causes compilation to fail.

D

 An error at line 14 causes compilation to fail.

E

 Compilation succeeds but an exception is thrown at line 14.

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相似问题和答案

第1题:

1. public class ReturnIt {  2. return Type methodA(byte x, double y) {  3. return (long)x / y * 2;  4. }  5. }  What is the narrowest valid returnType for methodA in line2?()  

  • A、 int
  • B、 byte
  • C、 long
  • D、 short
  • E、 float
  • F、 double

正确答案:F

第2题:

1. public class Target {  2. private int i = 0;  3. public int addOne() {  4. return ++i;  5. }  6. }  And:  1. public class Client {  2. public static void main(String[] args) {  3. System.out.println(new Target().addOne());  4. }  5. }  Which change can you make to Target without affecting Client?() 

  • A、 Line 4 of class Target can be changed to return i++;
  • B、 Line 2 of class Target can be changed to private int i = 1;
  • C、 Line 3 of class Target can be changed to private int addOne() {
  • D、 Line 2 of class Target can be changed to private Integer i = 0;

正确答案:D

第3题:

class A

{public int getNumber(int a){return a+1;}}

class B extends A

{public int getNumber(int a, char c){return a+2;}public static void main(String[] args){B b=new B();System.out.println(b.getNumber(0));}}

what is the result?()

A.compilation succeeds and 1 is printed

B.compilation succeeds and 2 is printed

C.compilation succeeds and 3 is printed

D.An error at this program cause compilation to fail


参考答案:A

第4题:

现有:   1. class Synapse {    2.    protected int gap() { return 7; }    3. }   4.     5. class Creb extends Synapse {    6.   // insert code here   7. }    分别插入到第 6 行,哪三行可以编译?()

  • A、 int gap() { return 7; }
  • B、 public int gap() { return 7; }
  • C、 private int gap(int x) { return 7; }
  • D、 protected Creb gap() { return this; }
  • E、 public int gap() { return Integer.getInteger ("42"); }

正确答案:B,C,E

第5题:

1. public class A {  2. public void doit() {  3. }  4. public String doit() {  5. return “a”;  6. }  7. public double doit(int x) {  8. return 1.0;  9. }  10.}  What is the result?() 

  • A、 An exception is thrown at runtime.
  • B、 Compilation fails because of an error in line 7.
  • C、 Compilation fails because of an error in line 4.
  • D、 Compilation succeeds and no runtime errors with class A occur.

正确答案:C

第6题:

1. class BaseClass {  2. private float x = 1.of;  3. protected float getVar() { return x; }  4. }  5. class SubClass extends BaseClass {  6. private float x = 2.Of;  7. // insert code here 8. }   Which two are valid examples of method overriding when inserted at line 7?() 

  • A、 float getVar() { return x; }
  • B、 public float getVar() { return x; }
  • C、 public double getVar() { return x; }
  • D、 protected float getVar() { return x; }
  • E、 public float getVar(float f) { return f; }

正确答案:B,D

第7题:

1. public interface A {  2. public void doSomething(String thing);  3. }  1. public class AImpl implements A {  2. public void doSomething(String msg) { }  3. }  1. public class B {  2. public A doit() {  3. // more code here  4. }  5.  6. public String execute() { 7. // more code here  8. }  9. }  1. public class C extends B {  2. public AImpl doit() {  3. // more code here  4. }  5.  6. public Object execute() {  7. // more code here  8. }  9. }  Which statement is true about the classes and interfaces in the exhibit?() 

  • A、 Compilation will succeed for all classes and interfaces.
  • B、 Compilation of class C will fail because of an error in line 2.
  • C、 Compilation of class C will fail because of an error in line 6.
  • D、 Compilation of class AImpl will fail because of an error in line 2.

正确答案:C

第8题:

写出程序运行的结果

Public class Base

Public virtual string Hello() {return “Base”;}

Public class Sub:Base

Public override string Hello() {return “Sub”;}

1. Base b = new Base(); b.Hello;

2. Sub s = new Sub(); s.Hello;

3. Base b = new Sub (); b.Hello;

4. Sub s = new Base(); s.Hello;


正确答案:
 

第9题:

Given classes defined in two different files:  1. package util;  2. public class BitUtils {  3. private static void process(byte[] b) { }  4. }  1. package app;  2. public class SomeApp {  3. public static void main(String[] args) {  4. byte[] bytes = new byte[256];  5. // insert code here  6. }  7. }  What is required at line 5 in class SomeApp to use the process method of BitUtils?() 

  • A、 process(bytes);
  • B、 BitUtils.process(bytes);
  • C、 app.BitUtils.process(bytes);
  • D、 util.BitUtils.process(bytes);
  • E、 import util.BitUtils. *; process(bytes);
  • F、 SomeApp cannot use the process method in BitUtils.

正确答案:F

第10题:

1. public class returnIt (  2. returnType methodA(byte x, double y) (  3. return (short) x/y * 2;  4. )  5. )   What is the valid returnType for methodA in line 2?()  

  • A、 Int
  • B、 Byte
  • C、 Long
  • D、 Short
  • E、 Float
  • F、 Double

正确答案:F

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