10. public class MyClass {
11.
12. public Integer startingI；
13. public void methodA（） {
14. Integer i = new Integer（25）；
15. startingI = i；
16. methodB（i）；
17. }
18. private void methodB（Integer i2） {
19. i2 = i2.intValue（）；
20.
21. }
22. }
If methodA is invoked， which two are true at line 20？（）
A. i2 == startingI returns true.
B. i2 == startingI returns false.
C. i2.equals（startingI） returns true.
D. i2.equals（startingI） returns false.
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public static void test（String str） {
int check = 4；
if （check = str.length（）） {
System.out.print（str.charAt（check -= 1） +“， “）；
} else {
System.out.print（str.charAt（0） + “， “）；
}
}
and the invocation：
test（”four”）；
test（”tee”）；
test（”to”）；
What is the result？（）
A. r， t， t，
B. r， e， o，
C. Compilation fails.
D. An exception is thrown at runtime.
11. public static void test（String str） {
12. if（str == null | str.lellgth（） == 0） {
13. System.out.println（”String is empty”）；
14. } else {
15. System.out.println（”String is not empty”）；
16. }
17. }
And the invocation：
31. test（llull）；
What is the result？（）
A. Au exception is thrown at runtime.
B. “String is empty” is printed to output.
C. Compilation fails because of au error in line 12.
D. “String is not empty” is printed to output.
A UNIX user named Bob wants to replace his chess program with a new one， but he is hot 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）
package com.company.application；
public class MainClass {
public static void main（String[] args） { }
}
And MainClass exists in the /apps/com/company/application directory. Assume the CLASSPATH environment variable is set to “.“ （current directory）.
Which two java commands entered at the command line will run MainClass？（）
A. java MainClass if run from the /apps directory
B. java com.company.application.MainClass if run from the /apps directory
C. java -classpath /apps com.company.application.MainClass if run from any directory
D. java -classpath . MainClass if run from the /apps/com/company/application directory
E. java -classpath /apps/com/company/application：. MainClass if run from the /apps directory
F. java com.company.application.MainClass if run from the /apps/com/company/application directory
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 JYM？（）
A. Jar A
B. Jar B
C. Jar C
D. Jar D
E. Jar E
A class games.cards.Poker is correctly defined in the jar file Poker.jar.
A user wants to execute the main method of Poker on a UNIX system using the command：
java games.cards.Poker
What allows the user to do this？（）
A. put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java
B. put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java/*.jar
C. Put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java/Poker.jar
D. put Poker.jar in directory /stuff/java/games/cards， and set the CLASSPATH to include /stuff/java
E. put Poker.jar in directory /stuff/java/games/cards， and set the CLASSPATH to include /stuffijava/*.jar
F. put Poker.jar in directory /stuff/java/games/cards， and set the CLASSPATH to include /stuff/java/Poker.jar
1. public class GC {
2. private Object o；
3. private void doSomethingElse（Object obj） { o = obj； }
4. public void doSomething（） {
5. Object o = new Object（）；
6. doSomethingElse（o）；
7. o = new Object（）；
8. doSomethingElse（null）；
9.o=null；
10. }
11. }
When the doSomething method is called， after which line does the Object created in line 5 become available for garbage collection？（）
A. Line 5
B. Line 6
C. Line 7
D. Line 8
E. Line 9
F. Line 10
11. class Snoochy {
12. Boochybooch；
13. public Snoochy（） { booch = new Boochy（this）； }
14. }
15.
16. class Boochy {
17. Snoochy snooch；
18. public Boochy（Snoochy s） { snooch = s； }
19. }
And the statements：
21. public static void main（String[] args） {
22. Snoochy snoog = new Snoochy（）；
23. snoog = null；
24. // more code here
25. }
Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line 23 executes？（）
A. None of these objects are eligible for garbage collection.
B. Only the object referenced by booch is eligible for garbage collection.
C. Only the object referenced by snoog is eligible for garbage collection.
D. Only the object referenced by snooch is eligible for garbage collection.
E. The objects referenced by snooch and booch are eligible for garbage collection.
11. rbo = new ReallyBigObject（）；
12. // more code here
13. rbo = null；
14. /* insert code here */
Which statement should be placed at line 14 to suggest that the virtual machine expend effort toward recycling the memory used by the object rbo？（）
A. System.gc（）；
B. Runtime.gc（）；
C. System.freeMemory（）；
D. Runtime.getRuntime（）.growHeap（）；
E. Runtime.getRuntime（）.freeMemory（）；
11. public void genNumbers（） {
12. ArrayList numbers = new ArrayList（）；
13. for （int i=0； i<10； i++） {
14. int value = i * （（int） Math.random（））；
15. Integer intObj = new Integer（value）；
16. numbers.add（intObj）；
17. }
18. System.out.println（numbers）；
19. }
Which line of code marks the earliest point that an object referenced by intObj becomes a candidate for garbage collection？（）
A. Line 16
B. Line 17
C. Line 18
D. Line 19
E. The object is NOT a candidate for garbage collection.
最新试题
Given that Triangle implements Runnable， and：Which two statements， inserted independently at both lines 35 and 41， tend to allow both threads to temporarily pause and allow the other thread to execute？（）
What is the result？（）
What is the result？（）
What can be a result？（）
What is the result？（）
Which two statements are true？（）
Given that t1 is a reference to a live thread， which is true？（）
Which two can be results？（）
Given： foo and bar are public references available to many other threads， foo refers to a Thread and bar is an Object. The thread foo is currently executing bar.wait（）. From another thread， what provides the most reliable way to ensure that foo will stop executing wait（）？（）
What is the result？（）