JAVA試習題英文版(答案)

1、一Which two demonstrate an “is a” relationship (Choose Two) A. public interface Person /語法錯了public class Employee extends Person B. public interface Shape /語法錯了public class Employee extends Sha pe C. public interface Color /語法錯了public class Employee extends Color D. public class Species public class

2、Animalprivate Species species;E. interface Component Class Container implements Component (         Private Component children;二which statement is true A. An anonymous inner class may be declared as final B. An anonymous inner class can be declared as private

3、C. An anonymous inner class can implement mutiple interfaces D. An anonymous inner class can access final variables in any enclosing scope （不能）E. Construction of an instance of a static inner class requires an instance of the encloing outer class 構(gòu)造一個靜態(tài)的內(nèi)部類對象需要構(gòu)造包含它的外部類的對象三. Given:1. package foo;2.&

4、#160; 3. public class Outer (4.    public static class Inner (5.    )6. )Which statement is true? A. An instance of the Inner class can be constructed with “new Outer.Inner ()”B. An instance of the inner class cannot be constructed outside of package foo他們都是public的，只要在外

5、部import就行C. An instance of the inner class can only be constructed from within the outer classD. From within the package bar, an instance of the inner class can be constructed with “new inner()”四Exhibit（展覽、陳列）：1 public class enclosinggone2 public class insideone3 4 public class inertest5 public stat

6、ic void main (String args)6 enclosingone eo = new enclosingone();7 /insert code here8 Which statement at line 7 constructs an instance of the inner class?A. InsideOne ei = eo.new InsideOne(); 寫程序試出來B. Eo.InsideOne ei = eo.new InsideOne();C InsideOne ei = EnclosingOne.new InsideOne();D.EnclosingOne I

7、nsideOne ei = eo.new InsideOne();五 1)  interface Foo    2)           int k=0;    3)       4) public class Test implements Foo    5)          

8、0;  public static void main(String args)    6)                        int i;    7)              

9、0;           Test test =new Test();    8)                           i=test.k;    9)   

10、;                        i=Test.k;   10)                       &#

11、160;  i=Foo.k;   11)                             12)  What is the result? A. Compilation succeeds.B. An error at line 2 causes compilation to fail.C.

12、An error at line 9 causes compilation to fail.D. An error at line 10 causes compilation to fail.E. An error at line 11 causes compilation to fail.六 /point X public class Foo public static void main(String args) PrintWriter out=new PrintWriter(new java.io.OutputStreamWriter(System.out),true); out.pri

13、ntln("Hello");     which statement at point X on line 1 allows this code to compile and run 在point X這個位置要填入什么代碼才能使程序運行A.import java.io.PrintWriter         B.include java.io.PrintWriter C.import java.io.OutputStreamWriter   D.inclu

14、de java.io.OutputStreamWriter E.No statement is needed 本來兩個都要import，但是后者OutputStreamWriter指定了包結(jié)構(gòu)java.io.OutputStreamWriter七 what is reserved words in java 保留字而非關(guān)鍵字A. run B. default C. implement D. import 八. which three are valid declaraction of a float （float作為整數(shù)是可以的，其余幾個都是double） A. float foo=

15、-1;  B. float foo=1.0;  C. float foo=42e1;  D. float foo=2.02f;  E. float foo=3.03d;  F. float foo=0x0123; 九.  Given:8.   int index = 1;9.   boolean test = new boolean3; （數(shù)組作為對象缺省初始化為false）10. boolean foo= test index; What is the result? A. foo

16、has the value of 0B. foo has the value of nullC. foo has the value of trueD. foo has the value of falseE. an exception is thrownF. the code will not compile十. Given:1. public class test(2. public static void main(Stringargs)3. String foo = args 1;4. String foo = args 2;5. String foo = args 3;6. 7. A

17、nd the command line invocation:Java Test What is the result? A. baz has the value of “”B. baz has the value of nullC. baz has the value of “red”D. baz has the value of “blue”E. bax has the value of “green”F. the code does not compileG. the program throws an exception(此題題目出錯了，重復定義了變量foo，如果沒有重復的話，應選G，

18、因為只傳遞了0-2三個數(shù)組元素，而題目中需要訪問args 3，所以會拋出數(shù)組越界異常)十一. int index=1; int foo=new int3; int bar=fooindex; /bar=0int baz=bar+index; /baz=1what is the result A. baz has a value of 0 B. baz has value of 1 C. baz has value of 2 D. an exception is thrown E. the code will not compile 十二. 1）public class Foo 2） publi

19、c static void main(String args) 3） String s; 4） System.out.println("s="+s); 5）  6）  what is the result A. The code compiles and “s=” is printed.B. The code compiles and “s=null” is printed.C. The code does not compile because string s is not initialized. D. The code does not comp

20、ile because string s cannot be referenced.E. The code compiles, but a NullPointerException is thrown when toString is called.十三. Which will declare a method that forces a subclass to implement it? （誰聲明了一個方法，子類必須實現(xiàn)它）A. public double methoda();B. static void methoda (double d1) C. public native double

21、 methoda();D. abstract public void methoda();E. protected void methoda (double d1)十四. You want subclasses in any package to have access to members of a superclass. Which is the most restrictive access modifier that will accomplish this objective?（你希望子類在任何包里都能訪問父類，為完成這個目的，下列哪個是最嚴格的訪問權(quán)限）A. PublicB. Pr

22、ivateC. ProtectedD. TransientE. No access modifier is qualified十五. Given:1. abstract class abstrctIt 2. abstract float getFloat ();3. )4. public class AbstractTest extends AbstractIt 5. private float f1= 1.0f;6. private float getFloat () return f1;7. What is the result?A. Compilation is successful.B

23、. An error on line 6 causes a runtime failure.（拋出實時異常）C. An error at line 6 causes compilation to fail.D. An error at line 2 causes compilation to fail.（子類覆蓋父類方法的時候，不能比父類方法具有更嚴格的訪問權(quán)限）十六. Click the exhibit button:1.  public class test2.  public int aMethod()3.  static int i=0; 4.  

24、;i+; 5.  return I; 6.  7.  public static void main (String args) 8.  test test = new test(); 9.  test.aMethod(); 10. int j = test.aMethod(); 11. System.out.printIn(j); 12. 13.      （局部變量不能聲明為靜態(tài)） What is the result? A. Compilation will fail.B. Compila

25、tion will succeed and the program will print “0”.C. Compilation will succeed and the program will print “1”.D. Compilation will succeed and the program will print “2”.十七.1)  class Super 2)  public float getNum()return 3.0f; 3)  4) 5)  public class Sub extends Super 6) 7)  wh

26、ich method, placed at line 6, will cause a compiler error A. public float getNum()return 4.0f; B. public void getNum() 返回值類型不同不足以構(gòu)成方法的重載C. public void getNum(double d) D. public double getNum(float d)return 4.0d; 十八. Which declaration prevents creating a subclass of an outer class  A.static class FooBar  B.pivate class Foobar  C.abstract class FooBar  D.final public class FooBar  E.final abstract class FooBar 抽象類不能聲明為final十九. byte array1,array2 byte array3 byte ar