格林模拟试题二参考答案(1)
添加时间: 2007-9-22 6:33:10 作者: JAVA认证考试 阅读次数:69 来源: http://www.d9soft.com
Answers
Answer 1)
1) The code will compile and run, printing out the words "My Func"
A class that contains an abstract method must be declared abstract itself, but may contain non abstract methods.
Answer 2)
4) The code will compile but will complain at run time that main is not correctly defined
In this example the parameter is a string not a string array as needed for the correct main method
Answer 3)
1) public
2) private
4) transient
The keyword transient is easy to forget as is not frequently used. Although a method may be considered to be friendly like in C++ it is not a Java keyword.
Answer 4)
2) The compiler will complain that the Base class is not declared as abstract.
If a class contains abstract methods it must itself be declared as abstract
Answer 5)
1) To get to access hardware that Java does not know about
3) To write optimised code for performance in a language such as C/C++
Answer 6)
4) Success in compilation and output of "amethod" at run time.
A final method cannot be ovverriden in a sub class, but apart from that it does not cause any other restrictions.
Answer 7)
4) Compilation and execution without error
It would cause a run time error if you had a call to amethod though.
Answer 8)
1)Compile time error: Base cannot be private
A top leve (non nested) class cannot be private.
Answer 9)
4) P1 compiles cleanly but P2 has an error at compile time
The package statement in P1.java is the equivalent of placing the file in a different directory to the file P2.java and thus when the compiler tries to compile P2 an error occurs indicating that superclass P1 cannot be found.
Answer 10)
2) An error at run time
This code will compile, but at run-time you will get an ArrayIndexOutOfBounds exception. This becuase counting in Java starts from 0 and so the 5th element of this array would be i[4].
Remember that arrays will always be initialized to default values wherever they are created.
Answer 11)
2)myarray.length;
The String class has a length() method to return the number of characters. I have sometimes become confused between the two.
Answer 12)
3) A Frame with one large button marked Four in the Centre
The default layout manager for a Frame is the BorderLayout manager. This Layout manager defaults to placing components in the centre if no constraint is passed with the call to the add method.
Answer 13)
4) Do nothing, the FlowLayout will position the component
Answer 14)
1) Use the setLayout method
Answer 15)
1) ipadx
2) fill
3) insets
Answer 16)
2) The buttons will run from left to right along the top of the frame
The call to the setLayout(new FlowLayout()) resets the Layout manager for the entire frame and so the buttons end up at the top rather than the bottom.
Answer 17)
2) It is a field of the GridBagConstraints class for controlling component placement
3) A valid settting for the anchor field is GridBagconstraints.NORTH
Answer 18)
4) Clean compile but no output at runtime
This is a bit of a sneaky one as I have swapped around the names of the methods you need to define and call when running a thread. If the for loop were defined in a method called public void run() and the call in the main method had been to b.start() The list of values from 0 to 9 would have been output.
Answer 19)
2) false
You can re-use the same instance of the GridBagConstraints when added successive components.
Answer 20)
4) An interface that ensures that implementing classes cannot contain duplicates
Answer 21)
2) The add method returns false if you attempt to add an element with a duplicate value
I find it a surprise that you do not get an exception.
Answer 22)
1) The program exits via a call to exit(0);
2) The priority of another thread is increased
3) A call to the stop method of the Thread class
Note that this question asks what can cause a thread to stop executing, not what will cause a thread to stop executing. Java threads are somewhat platform dependent and you should be carefull when making assumptions about Thread priorities. On some platforms you may find that a Thread with higher priorities gets to "hog" the processor. You can read up on this in more detail at
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