SUN CERTIFIED PROGRAMMER FOR THE JAVA 2 PLATFORM EXAM QUESTION AND ANSWER
QUESTION: 21
Given:
11. abstract class Vehicle { public int speed() { return 0; }
12. class Car extends Vehicle { public int speed() { return 60; }
13. class RaceCar extends Car { public int speed() { return 150; }
...
21. RaceCar racer = new RaceCar();
22. Car car = new RaceCar();
23. Vehicle vehicle = new RaceCar();
24. System.out.println(racer.speed() + ", " +
car.speed()
25. + ", " + vehicle.speed());
What is the result?
A. 0, 0, 0
B. 150, 60, 0
C. Compilation fails.
D. 150, 150, 150
E. An exception is thrown at runtime.
Answer: D
QUESTION: 22
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.
Answer: C
QUESTION: 23
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
Answer: A
QUESTION: 24
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.
Answer: E
QUESTION: 25
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.
Answer: C
QUESTION: 26
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. 18. d = df.parse(ds);
B. 18. d = df.getDate(ds);
C. 18. try {
19. d = df.parse(ds);
20. } catch(ParseException e) { };
D. 18. try {
19. d = df.getDate(ds);
20. } catch(ParseException e) { };
Answer: C
QUESTION: 27
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 );
Answer: B
QUESTION: 28
Given:
1. public class TestString1 {
2. public static void main(String[] args) {
3. String str = "420";
4. str += 42;
5. System.out.print(str);
6. }
7. }
What is the output?
A. 42
B. 420
C. 462
D. 42042
E. Compilation fails.
F. An exception is thrown at runtime.
Answer: D
QUESTION: 29
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.
Answer: D
QUESTION: 30
Given that the current directory is empty, and that the user has
read and write
permissions, and the following:
11. import java.io.*;
12. public class DOS {
13. public static void main(String[] args) {
14. File dir = new File("dir");
15. dir.mkdir();
16. File f1 = new File(dir, "f1.txt");
17. try {
18. f1.createNewFile();
19. } catch (IOException e) { ; }
20. File newDir = new File("newDir");
21. dir.renameTo(newDir);
22. }
23. }
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.
Answer: E
QUESTION: 31
Given:
22. StringBuilder sb1 = new StringBuilder("123");
23. String s1 = "123";
24. // insert code here
25. System.out.println(sb1 + " " + s1);
Which code fragment, inserted at line 24, outputs "123abc
123abc"?
A. sb1.append("abc"); s1.append("abc");
B. sb1.append("abc"); s1.concat("abc");
C. sb1.concat("abc"); s1.append("abc");
D. sb1.concat("abc"); s1.concat("abc");
E. sb1.append("abc"); s1 = s1.concat("abc");
F. sb1.concat("abc"); s1 = s1.concat("abc");
G. sb1.append("abc"); s1 = s1 +
s1.concat("abc");
H. sb1.concat("abc"); s1 = s1 +
s1.concat("abc");
Answer: E
QUESTION: 32
Which code, inserted at line 14, will allow this class to
correctly serialize and deserialize?
import
1.Import java.io.*;
2.public class foo implements Serialisable{
3.public int x,y;
4.public Foo(int x,int y){this.x=x;
this.y=y;
5. }
6.private void writeObject(
ObjectOutputsStream s)
7. throws IOException{
8.s.writeInt(x);
9. s.writeInt(y);
10.}
11.private void readObject(ObjectInputStream)
12 .throws IOException,ClassNotFoundException
13.{
14.//insert code here
15.
16.}
17.}
A.
s.defaultReadObject();
B.
this = s.defaultReadObject();
C. y
= s.readInt(); x = s.readInt();
D. x
= s.readInt(); y = s.readInt();
Answer: D
QUESTION: 33
Given:
1.
public class LineUp {
2.
public static void main(String[] args) {
3.
double d = 12.345;
4.
// insert code here
5. }
6. }
Which
code fragment, inserted at line 4, produces the output | 12.345|?
A.
System.out.printf("|%7d| \n", d);
B.
System.out.printf("|%7f| \n", d);
C.
System.out.printf("|%3.7d| \n", d);
D.
System.out.printf("|%3.7f| \n", d);
E.
System.out.printf("|%7.3d| \n", d);
F.
System.out.printf("|%7.3f| \n", d);
Answer: F
QUESTION: 34
Given:
11.
public class Test {
12.
public static void main(String [] args) {
13.
int x = 5;
14.
boolean b1 = true;
15.
boolean b2 = false;
16.
17.
if ((x == 4) && !b2 )
18.
System.out.print("1 ");
19.
System.out.print("2 ");
20.
if ((b2 = true) && b1 )
21.
System.out.print("3 ");
22.
}
23.
}
What
is the result?
A. 2
B. 3
C. 1
2
D. 2
3
E. 1
2 3
F.
Compilation fails.
G.
An exception is thrown at runtime.
Answer: D
QUESTION: 35
Given:
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.ClassCastException?
A.
Alpha a = x;
B.
Foo f = (Delta)x;
C.
Foo f = (Alpha)x;
D.
Beta b = (Beta)(Alpha)x;
Answer: B
QUESTION: 36
Given:
22.
public void go() {
23.
String o = "";
24.
z:
25.
for(int x = 0; x < 3; x++) {
26.
for(int y = 0; y < 2; y++) {
27.
if(x==1) break;
28.
if(x==2 && y==1) break z;
29.
o = o + x + y;
30.
}
31.
}
32.
System.out.println(o);
33.
}
What
is the result when the go() method is invoked?
A.
00
B.
0001
C.
000120
D.
00012021
E.
Compilation fails.
F.
An exception is thrown at runtime.
Answer: C
QUESTION: 37
Given:
11.
static void test() throws RuntimeException {
12.
try {
13.
System.out.print("test ");
14.
throw new RuntimeException();
15.
}
16.
catch (Exception ex) { System.out.print("exception "); }
17.
}
18.
public static void main(String[] args) {
19.
try { test(); }
20.
catch (RuntimeException ex) { System.out.print("runtime "); }
21.
System.out.print("end ");
22.
}
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.
Answer: D
QUESTION: 38
Given:
33.
try {
34.
// some code here
35.
} catch (NullPointerException e1) {
36.
System.out.print("a");
37.
} catch (Exception e2) {
38.
System.out.print("b");
39.
} finally {
40.
System.out.print("c");
41.
}
If
some sort of exception is thrown at line 34, which output is possible?
A. a
B. b
C. c
D.
ac
E.
abc
Answer: D
QUESTION: 39
Given:
31.
// some code here
32.
try {
33.
// some code here
34.
} catch (SomeException se) {
35.
// some code here
36.
} finally {
37.
// some code here
38.
}
Under
which three circumstances will the code on line 37 be executed? (Choose three.)
A.
The instance gets garbage collected.
B.
The code on line 33 throws an exception.
C.
The code on line 35 throws an exception.
D.
The code on line 31 throws an exception.
E.
The code on line 33 executes successfully.
Answer: B,C,E
QUESTION: 40
Given:
10.
int x = 0;
11.
int y = 10;
12.
do {
13.
y--;
14.
++x;
15.
} while (x < 5);
16.
System.out.print(x + "," + y);
What
is the result?
A.
5,6
B.
5,5
C.
6,5
D.
6,6
Answer: B
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