单选题11. public void addStrings(List list) {  12. list.add(”foo”);  13. list.add(”bar”);  14. }  What must you change in this method to compile without warnings?()A  add this code after line 11: list = (List) list;B  change lines 12 and 13 to: list.add(”foo

题目
单选题
11. public void addStrings(List list) {  12. list.add(”foo”);  13. list.add(”bar”);  14. }  What must you change in this method to compile without warnings?()
A

 add this code after line 11: list = (List) list;

B

 change lines 12 and 13 to: list.add(”foo”); list.add(”bar”);

C

 change the method signature on line 11 to: public void addStrings(List< extends String> list) {

D

 change the method signature on line 11 to: public void addStrings(List< super String> list) {

E

 No changes are necessary. This method compiles without warnings.

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相似问题和答案

第1题:

3.importjava.util.*;4.classForInTest{5.staticListlist=newArrayList();6.7.publicstaticvoidmain(String[]args){8.list.add("a");list.add("b");list.add("c");9.//insertcodehere10.System.out.print(o);11.}12.}哪一行插入到第9行将导致输出abc”?()

A.for(Objecto:list)

B.for(Iteratoro:list)

C.for(Objecto:list.iterator())

D.for(Iteratoro:list.iterator();o.hasNext();)


参考答案:A

第2题:

publicstaticvoidsearch(Listlist){list.clear();list.add(”b”);list.add(”a”);list.add(”c”);System.out.println(Collections.binarySearch(list,a”));}WhatistheresultofcallingsearchwithavalidListimplementation?()

A.0

B.1

C.a

D.b

E.c

F.Theresultisundefined.


参考答案:F

第3题:

现有:3.importjava.util.*;4.classForInTest{5.staticListlist=newArrayList();6.publicstaticvoidmain(String[]args){7.8.list.add("a");list.add("b");list.add("c");9.//insertcodehere10.System.out.print(o);}}哪一行插入到第9行将导致输出abc”?()

A.for(Objecto:list)

B.for(Iteratoro:list)

C.for(Objecto:list.iterator())

D.for(Iteratoro:list.iterator();o.hasNext();)


参考答案:A

第4题:

11. public void addStrings(List list) {  12. list.add(”foo”);  13. list.add(”bar”);  14. }  What must you change in this method to compile without warnings?() 

  • A、 add this code after line 11: list = (List) list;
  • B、 change lines 12 and 13 to: list.add(”foo”); list.add(”bar”);
  • C、 change the method signature on line 11 to: public void addStrings(List< extends String> list) {
  • D、 change the method signature on line 11 to: public void addStrings(List< super String> list) {
  • E、 No changes are necessary. This method compiles without warnings.

正确答案:D

第5题:

publicstaticIteratorreverse(Listlist){Collections.reverse(list);returnlist.iterator();}publicstaticvoidmain(String[]args){Listlist=newArrayList();list.add(”1”);list.add(”2”);list.add(”3”);for(Objectobj:reverse(list))System.out.print(obj+,”);}Whatistheresult?()

A.3,2,1,

B.1,2,3,

C.Compilationfails.

D.Thecoderunswithnooutput.

E.Anexceptionisthrownatruntime.


参考答案:C

第6题:

现有:1.importjava.util.*;

现有:

1.importjava.util.*;

2.classForInTest{

3.staticListlist-newArrayList():

4.

5.staticListgetList(){returnlist;}

6.

7.publicstaticvoidmain(Strincj[]args){

8.list.add("a");list.add("b");list.add("c");

9.//insertcodehere

10.System.out.print(o);

11.}

12.}

第9行插入哪一项将输出abc?()


参考答案:D

第7题:

publicvoidaddStrings(Listlist){12.list.add(”foo”);13.list.add(”bar”);14.}Whatmustyouchangeinthismethodtocompilewithoutwarnings?()

A.addthiscodeafterline11:list=(List)list;

B.changelines12and13to:list.add(”foo”);list.add(”bar”);

C.changethemethodsignatureonline11to:publicvoidaddStrings(List<extendsString>list){

D.changethemethodsignatureonline11to:publicvoidaddStrings(List<superString>list){

E.Nochangesarenecessary.Thismethodcompileswithoutwarnings.


参考答案:D

第8题:

1.importjava.util.*;2.classForInTest{3.staticListlist=newArrayList();4.5.staticListgetList(){returnlist;}6.7.publicstaticvoidmain(String[]args){8.list.add("a");list.add("b");list.add("c");9.//insertcodehere10.System.out.print(o);11.}12.}第9行插入哪一项将输出abc?()

A.for(charo:list)

B.for(Objecto:getList())

C.for(Objecto:getList();)

D.for(Objecto:o.getList())


参考答案:B

第9题:

现有:   3.import java.util.*;   4.class ForInTest {   5.static List list = new ArrayList();  6.public static void main (String [] args){   7.  8.list.add("a"); list.add("b"); list.add("c");   9.//insert code here      10.System.out.print(o);  } }   哪一行插入到第9行将导致输出“abc”?() 

  • A、 for(Object o : list)
  • B、 for(Iterator o : list)
  • C、 for(Object o : list.iterator())
  • D、 for(Iterator o : list.iterator(); o.hasNext (); )

正确答案:A

第10题:

10. interface A { void x(); }  11. class B implements A { public void x() { } public voidy() { } }  12. class C extends B { public void x() {} }  And:  20. java.util.List list = new java.util.ArrayList();  21. list.add(new B());  22. list.add(new C());  23. for (A a:list) {  24. a.x();  25. a.y();;  26. }  What is the result?() 

  • A、 The code runs with no output.
  • B、 An exception is thrown at runtime.
  • C、 Compilation fails because of an error in line 20.
  • D、 Compilation fails because of an error in line 21.
  • E、 Compilation fails because of an error in line 23.
  • F、 Compilation fails because of an error in line 25.

正确答案:F

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