1Z0-851 全真模擬試験 DEMO

問題15: 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")
;
正解: E
18.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.
正解: E
19.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. It is true that j==i.
B. It is false that j==i.
C. An exception is thrown at runtime.
D. Compilation fails because of an error in line 13.
正解: D
20.Given:
11. String test = "Test A. Test B. Test C.";
12. // insert code here
13. String[] result = test.split(regex);
Which regular expression, inserted at line 12, correctly splits test into "Test A", "Test B", and "Test
C"?
A. String regex = "";
B. String regex = " ";
C. String regex = ".*";
D. String regex = "\\s";
E. String regex = "\\.\\s*";
F. String regex = "\\w[ \.] +";
正解: E
21.Given:
5. import java.util.Date;
6. import java.text.DateFormat;
21. DateFormat df;
22. Date date = new Date();
23. // insert code here
24. String s = df.format(date);
Which code fragment, inserted at line 23, allows the code to compile?
A. df = new DateFormat();
B. df = Date.getFormat();
C. df = date.getFormat();
D. df = DateFormat.getFormat();
E. df = DateFormat.getInstance();
正解: E
22.Given a class Repetition:
1. package utils;
2.
3. public class Repetition {
4. public static String twice(String s) { return s + s; }
5. } and given another class Demo: 1. // insert code here
2.
3. public class Demo {
4. public static void main(String[] args) {
5. System.out.println(twice("pizza"));
6. }
7. }
Which code should be inserted at line 1 of Demo.java to compile and run Demo to print
"pizzapizza"?
A. import utils.*;
B. static import utils.*;
C. import utils.Repetition.*;
D. static import utils.Repetition.*;
E. import utils.Repetition.twice();
F. import static utils.Repetition.twice;
G. static import utils.Repetition.twice;
正解: F
23.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. /home/bob/Chess.class
C. /test/games/Chess.class
D. /usr/lib/games/Chess.class
E. /home/bob/games/Chess.class
F. inside jarfile /opt/java/lib/Games.jar (with a correct manifest)
G. inside jarfile /home/bob/downloads/Games.jar (with a correct manifest)
正解: C
24.Given:
3. interface Animal { void makeNoise(); }
4. class Horse implements Animal {
5. Long weight = 1200L;
6. public void makeNoise() { System.out.println("whinny"); }
7. }
8. public class Icelandic extends Horse {
9. public void makeNoise() { System.out.println("vinny"); }
10. public static void main(String[] args) {
11. Icelandic i1 = new Icelandic();
12. Icelandic i2 = new Icelandic();
13. Icelandic i3 = new Icelandic();
14. i3 = i1; i1 = i2; i2 = null; i3 = i1;
15. }
16.
}
When line 15 is reached, how many objects are eligible for the garbage collector?A. 0
B. 1
C. 2
D. 3
E. 4
F. 6
正解: E
25.Click the Exhibit button. Given the fully-qualified class names: com.foo.bar.Dog
com.foo.bar.blatz.Book com.bar.Car com.bar.blatz.Sun Which graph represents the correct directory
structure for a JAR file from which those classes can be used by the compiler and JVM?
A. Jar A
B. Jar B
C. Jar C
D. Jar D
E. Jar E
正解: A