[1Z0-851A] Question 21~30

QUESTION 21

Given:

 

5.    class Building { }

6.    public class Barn extends Building {

7.        public static void main(String[] args) {

8.             Building build1 = new Building();

9.             Barn barn1 = new Barn();

10.            Barn barn2 = (Barn) build1;

11.            Object obj1 = (Object) build1;

12.            String str1 = (String) build1;

13.            Building build2 = (Building) barn1;

14.   }

15. }

 

Which is true?

 

A.   If line 10 is removed, the compilation succeeds.

B.   If line 11 is removed, the compilation succeeds.

C.   If line 12 is removed, the compilation succeeds.

D.   If line 13 is removed, the compilation succeeds.

E.   More than one line must be removed for compilation to succeed.

 

Correct Answer: C Section: All Explanation

 

Explanation/Reference:

 

Cannot cast from Building to String

 

 

QUESTION 22

A team of programmers is reviewing a proposed API for a new utility class. After some discussion, they realize that they can reduce the number of methods in the API without losing any functionality. If they implement the new design, which two OO principles will they be promoting?

 

A.   Looser coupling

B.   Tighter coupling

C.   Lower cohesion

D.   Higher cohesion

E.   Weaker encapsulation

F.   Stronger encapsulation

 

Correct Answer: A Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 23

Given:

 

21.  class Money {

22.       private String country = "Canada";

23.       public String getC() { return country; }

24. }

25.  class Yen extends Money {

26.       public String getC() { return super.country; }

27. }

28.  public class Euro extends Money {

29.       public String getC(int x) { return super.getC(); }

30.       public static void main(String[] args) {

31.             System.out.print(new Yen().getC() + " " + new Euro().getC());

32.    }

33. }

 

What is the result?

 

A.   Canada

B.   null Canada

C.   Canada null

D.   Canada Canada

E.   Compilation fails due to an error on line 26.

F.   Compilation fails due to an error on line 29.

 

Correct Answer: E Section: All Explanation

 

Explanation/Reference:

The field Money.country is not visible

 

 

QUESTION 24

Assuming that the serializeBanana() and the deserializeBanana() methods will correctly use Java serialization and given:

 

13.  import java.io.*;

14.  class Food implements Serializable {int good = 3;}

15.  class Fruit extends Food {int juice = 5;}

16.  public class Banana extends Fruit {

17.       int yellow = 4;

18.       public static void main(String [] args) {

19.             Banana b = new Banana(); Banana b2 = new Banana();

20.             b.serializeBanana(b); // assume correct serialization

21.             b2 = b.deserializeBanana(); // assume correct

22.             System.out.println("restore "+b2.yellow+ b2.juice+b2.good);

24.    }

25.    // more Banana methods go here

50. }

 

What is the result?

 

A.   restore 400

B.   restore 403

C.   restore 453

D.   Compilation fails.

E.   An exception is thrown at runtime.

 

Correct Answer: C Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 25

Given a valid DateFormat object named df, and

 

16.  Date d = new Date(0L);

17.  String ds = "December 15, 2004";

18.  //insert code here

 

What updates d's value with the date represented by ds?

 

A.   d = df.parse(ds);

B.   d = df.getDate(ds);

C.   try {

d = df.parse(ds);

} catch(ParseException e) { };

D.   try {

d = df.getDate(ds);

} catch(ParseException e) { };

 

Correct Answer: C Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 26

Given:

 

11.  double input = 314159.26;

12.  NumberFormat nf = NumberFormat.getInstance(Locale.ITALIAN);

13.  String b;

14.  //insert code here

 

Which code, inserted at line 14, sets the value of b to 314.159,26?

 

A.   b = nf.parse( input );

B.   b = nf.format( input );

C.   b = nf.equals( input );

D.   b = nf.parseObject( input );

 

Correct Answer: B Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 27

Given:

 

public class TestString1 {

public static void main(String[] args) { String str = "420";

str += 42; System.out.print(str);

}

}

 

What is the output?

 

       A. 42

       B. 420

       C.  462

       D.  42042

E.   Compilation fails.

F.   An exception is thrown at runtime.

 

Correct Answer: D Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 28

Which capability exists only in  java.io.FileWriter?

 

A.   Closing an open stream.

B.   Flushing an open stream.

C.   Writing to an open stream.

D.   Writing a line separator to an open stream.

 

Correct Answer: D Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 29

Given that the current directory is empty, and that the user has read and write permissions, and the following:

 

import java.io.*;

public class DOS {

public static void main(String[] args) { File dir = new File("dir"); dir.mkdir();

File f1 = new File(dir, "f1.txt");

try {

f1.createNewFile();

} catch (IOException e) { ; } File newDir = new File("newDir"); dir.renameTo(newDir);

}

}

 

Which statement is true?

 

A.   Compilation fails.

B.   The file system has a new empty directory named dir.

C.   The file system has a new empty directory named newDir.

D.   The file system has a directory named dir, containing a file f1.txt.

E.   The file system has a directory named newDir, containing a file f1.txt.

 

Correct Answer: E Section: All Explanation

 

Explanation/Reference:

 

 

QUESTION 30

Given:

 

static void test() throws RuntimeException {

try {

System.out.print("test ");

throw new RuntimeException();

}

catch (Exception ex) { System.out.print("exception "); }

}

 

public static void main(String[] args) {

try { test(); }

catch (RuntimeException ex) { System.out.print("runtime "); } System.out.print("end ");

}

 

What is the result?

 

A.   test end

B.   Compilation fails.

C.   test runtime end

D.   test exception end

E.   A Throwable is thrown by main at runtime.

 

Correct Answer: D Section: All Explanation

 

Explanation/Reference:

 

 

 

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Source from : Oracle.Exactexams.1z0-851.v2013-11-27.by.SomeBody ().pdf