默认题库 - OCJP(310-065)

多选题

Given： class ClassA {} class ClassB extends ClassA {} class ClassC extends ClassA {} and： ClassA p0 = new ClassA（）； ClassB p1 = new ClassB（）； ClassC p2 = new ClassC（）； ClassA p3 = new ClassB（）； ClassA p4 = new ClassC（）； Which three are valid？（）

A. p0 = p1；
B. p1 = p2；
C. p2 = p4；
D. p2 = （ClassC）p1；
E. p1 = （ClassB）p3；
F. p2 = （ClassC）p4；

多选题

Which two code fragments will execute the method doStuff（） in a separate thread？（）

A. new Thread（） {public void run（） { doStuff（）； }}；
B. new Thread（） {public void start（） { doStuff（）； }}；
C. new Thread（） {public void start（） { doStuff（）； }}.run（）；
D. new Thread（） {public void run（） { doStuff（）； }}.start（）；
E. new Thread（new Runnable（） {public void run（） { doStuff（）； }}）.start（）；

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多选题

Given： 35.String #name = "Jane Doe"； 36.int $age = 24； 37.Double _height = 123.5； 38.double ~temp = 37.5； Which two statements are true？（）

A. Line 35 will not compile.
B. Line 36 will not compile.
C. Line 37 will not compile.
D. Line 38 will not compile.

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多选题

Which two scenarios are NOT safe to replace a StringBuffer object with a StringBuilder object？（）

A. When using versions of Java technology earlier than 5.0.
B. When sharing a StringBuffer among multiple threads.
C. When using the java.io class StringBufferInputStream.
D. When you plan to reuse the StringBuffer to build more than one string.

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单选题

A team of programmers is involved in reviewing a proposed design for a new utility class. After some discussion， they realize that the current design allows other classes to access methods in the utility class that should be accessible only to methods within the utility class itself. What design issue has the team discovered？（）

A. Tight coupling
B. Low cohesion
C. High cohesion
D. Loose coupling
E. Weak encapsulatio

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多选题

A developer is creating a class Book， that needs to access class Paper. The Paper class is deployed in a JAR named myLib.jar. Which three， taken independently， will allow the developer to use the Paper class while compiling the Bookclass？（）

A. The JAR file is located at $JAVA_HOME/jre/classes/myLib.jar.
B. The JAR file is located at $JAVA_HOME/jre/lib/ext/myLib.jar..
C. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar/Paper.class.
D. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar.
E. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac - cp /foo/myLib.jar/Paper Book.java.
F. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac - classpath /foo/myLib.jar Book.java

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单选题

A UNIX user named Bob wants to replace his chess program with a new one， but he is not sure where theold 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.cla

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