1Z0-851：最新的Oracle認證1Z0-851考題，Java Standard Edition 6 Programmer Certified Professional Exam認證

問題1
Given:
11.class Converter {
12.public static void main(String[] args) {
13.Integer i = args[0];
14.int j = 12;
15.System.out.println("It is " + (j==i) + " that j==i.");
16.}
17.}
What is the result when the programmer attempts to compile the code and run it with the command java Converter 12?

A. An exception is thrown at runtime.

B. Compilation fails because of an error in line 13.

C. It is false that j==i.

D. It is true that j==i.

正確答案: B

問題2
DRAG DROP
Click the Task button.

正確答案:

問題3
Given:
10.class Nav{
11.public enum Direction { NORTH, SOUTH, EAST, WEST }
12.}
13.public class Sprite{
14.// insert code here
15.}
Which code, inserted at line 14, allows the Sprite class to compile?

A. Direction d = NORTH;

B. Direction d = Direction.NORTH;

C. Nav.Direction d = Nav.Direction.NORTH;

D. Nav.Direction d = NORTH;

正確答案: C

問題4
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. ac

B. b

C. c

D. a

E. abc

正確答案: A

問題5
Given:
3.import java.util.*;
4.public class G1 {
5.public void takeList(List<? extends String> list) {
6.// insert code here
7.}
8.}
Which three code fragments, inserted independently at line 6, will compile? (Choose three.)

A. Object o = list;

B. list = new ArrayList<String>();

C. String s = list.get(0);

D. list = new ArrayList<Object>();

E. list.add("foo");

正確答案: A,B,C

問題6
Given:
10.public class SuperCalc {
11.protected static int multiply(int a, int b) { return a * b;}
12.} and:
20.public class SubCalc extends SuperCalc{
21.public static int multiply(int a, int b) {
22.int c = super.multiply(a, b);
23.return c;
24.}
25.} and:
30.SubCalc sc = new SubCalc ();
31.System.out.println(sc.multiply(3,4));
32.System.out.println(SubCalc.multiply(2,2));
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 22.

D. Compilation fails because of an error in line 21.

E. 12

F. Compilation fails because of an error in line 31.

正確答案: C

問題7
Which two code fragments are most likely to cause a StackOverflowError? (Choose two.)

A. for(int y = 10; y < 10; y++)
doStuff(y);

B. for(int x = 0; x < 1000000000; x++)
doStuff(x);

C. void doOne(int x) { doTwo(x); }
void doTwo(int y) { doThree(y); }
void doThree(int z) { doTwo(z); }

D. int []x = {1,2,3,4,5};
for(int y = 0; y < 6; y++)
System.out.println(x[y]);

E. static int[] x = {7,6,5,4};
static { x[1] = 8;
x[4] = 3; }

F. void counter(int i) { counter(++i); }

正確答案: C,F

問題8
Given:
21.abstract class C1 {
22.public C1() { System.out.print(1); }
23.}
24.class C2 extends C1 {
25.public C2() { System.out.print(2); }
26.}
27.class C3 extends C2 {
28.public C3() { System.out.println(3); }
29.}
30.public class Ctest {
31.public static void main(String[] a) { new C3(); }
32.}
What is the result?

A. An exception is thrown at runtime.

B. 23

C. 321

D. 3

E. Compilation fails.

F. 123

G. 32

正確答案: F

問題9
Click the Exhibit button. What is the result?

A. An exception is thrown at runtime.

B. 0000

C. 4321

D. Compilation fails because of an error in line 18.

正確答案: D

問題10
Given that the current directory is empty, and that the user has read and write privileges to the current directory, and the following:
1.import java.io.*;
2.public class Maker {
3.public static void main(String[] args) {
4.File dir = new File("dir");
5.File f = new File(dir, "f");
6.}
7.}
Which statement is true?

A. Both a new file and a new directory are created on the file system.

B. Nothing is added to the file system.

C. Only a new file is created on the file system.

D. Only a new directory is created on the file system.

E. Compilation fails.

正確答案: B

問題11
Given:
1.public class Threads4 {
2.public static void main (String[] args) {
3.new Threads4().go();
4.}
5.public void go() {
6.Runnable r = new Runnable() {
7.public void run() {
8.System.out.print("foo");
9.}
10.};
11.Thread t = new Thread(r);
12.t.start();
13.t.start();
14.}
15.}
What is the result?

A. An exception is thrown at runtime.

B. The code executes normally, but nothing is printed.

C. The code executes normally and prints "foo".

D. Compilation fails.

正確答案: A

問題12
Given:
11.public class Test {
12.public enum Dogs {collie, harrier, shepherd};
13.public static void main(String [] args) {
14.Dogs myDog = Dogs.shepherd;
15.switch (myDog) {
16.case collie:
17.System.out.print("collie ");
18.case default:
19.System.out.print("retriever ");
20.case harrier:
21.System.out.print("harrier ");
22.}
23.}
24.}
What is the result?

A. An exception is thrown at runtime.

B. retriever harrier

C. harrier

D. retriever

E. Compilation fails.

F. shepherd

正確答案: E

問題13
Given:
11.public static void main(String[] args) {
12.String str = "null";
13.if (str == null) {
14.System.out.println("null");
15.} else (str.length() == 0) {
16.System.out.println("zero");
17.} else {
18.System.out.println("some");
19.}
20.}
What is the result?

A. An exception is thrown at runtime.

B. zero

C. some

D. null

E. Compilation fails.

正確答案: E

問題14
Given:
1.import java.util.*;
2.public class WrappedString {
3.private String s;
4.public WrappedString(String s) { this.s = s; }
5.public static void main(String[] args) {
6.HashSet<Object> hs = new HashSet<Object>();
7.WrappedString ws1 = new WrappedString("aardvark");
8.WrappedString ws2 = new WrappedString("aardvark");
9.String s1 = new String("aardvark");
10.String s2 = new String("aardvark");
11.hs.add(ws1); hs.add(ws2); hs.add(s1); hs.add(s2);
12.System.out.println(hs.size()); } } What is the result?

A. An exception is thrown at runtime.

B. 2

C. 4

D. 0

E. 1

F. 3

G. Compilation fails.

正確答案: F

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