Oracle 1Z0-851 問題集

質問 1：
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. Nav.Direction d = Nav.Direction.NORTH;
B. Direction d = NORTH;
C. Nav.Direction d = NORTH;
D. Direction d = Direction.NORTH;
正解：A

質問 2：
DRAG DROP
Click the Task button.

正解：


質問 3：
Given:
5.class Atom {
6.Atom() { System.out.print("atom "); }
7.}
8.class Rock extends Atom {
9.Rock(String type) { System.out.print(type); }
10.}
11.public class Mountain extends Rock {
12.Mountain() {
13.super("granite ");
14.new Rock("granite ");
15.}
16.public static void main(String[] a) { new Mountain(); }
17.}
What is the result?
A. atom granite atom granite
B. An exception is thrown at runtime.
C. Compilation fails.
D. granite granite
E. atom granite
F. atom granite granite
正解：A

質問 4：
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. 1 2
C. 3
D. An exception is thrown at runtime.
E. Compilation fails.
F. 1 2 3
G. 2 3
正解：G

質問 5：
A UNIX user named Bob wants to replace his chess program with a new one, but he is not sure where the old one is installed. Bob is currently able to run a Java chess program starting from his home directory /home/bob using the command: java -classpath /test:/home/bob/downloads/*.jar games.Chess Bob's CLASSPATH is set (at login time) to: /usr/lib:/home/bob/classes:/opt/java/lib:/opt/java/lib/*.jar What is a possible location for the Chess.class file?
A. /test/Chess.class
B. /test/games/Chess.class
C. /home/bob/games/Chess.class
D. inside jarfile /home/bob/downloads/Games.jar (with a correct manifest)
E. /usr/lib/games/Chess.class
F. inside jarfile /opt/java/lib/Games.jar (with a correct manifest)
G. /home/bob/Chess.class
正解：B

質問 6：
Given:
1.package test;
2.3.
class Target {
4.public String name = "hello";
5.}
What can directly access and change the value of the variable name?
A. any class that extends Target
B. any class in the test package
C. only the Target class
D. any class
正解：B

質問 7：
Given:
12.Date date = new Date();
13.df.setLocale(Locale.ITALY);
14.String s = df.format(date);
The variable df is an object of type DateFormat that has been initialized in line 11. What is the result if this code is run on December 14, 2000?
A. The value of s is 14-dic-2000.
B. Compilation fails because of an error in line 13.
C. The value of s is Dec 14, 2000.
D. An exception is thrown at runtime.
正解：B

質問 8：
Given:
11.public class Person {
12.private name;
13.public Person(String name) {
14.this.name = name;
15.}
16.public int hashCode() {
17.return 420;
18.}
19.}
Which statement is true?
A. The time to determine whether a Person object is contained in a HashSet is constant and does NOT depend on the size of the map.
B. The time to find the value from HashMap with a Person key depends on the size of the map.
C. Deleting a Person key from a HashMap will delete all map entries for all keys of type Person.
D. Inserting a second Person object into a HashSet will cause the first Person object to be
removed as a duplicate.
正解：B