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.
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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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Answer 23)
4) The class can only access final variables
Answer 24)
1) To call from the currently running thread to allow another thread of the same or higher priority to run
Option 3 looks plausible but there is no guarantee that the thread that grabs the cpu time will be of a higher priority. It will depend on the threading algorithm of the Java Virtual Machine and the underlying operating system
Answer 25)
4) Compilation and running with output 0 to 9
Answer 26)
1) None of these options
Because of the lack of a break statement after the break 10; statement the actual output will be
"ten" followed by "twenty"
Answer 27)
4) System.gc();
Answer 28)
1) Compilation succeeds and at run time an output of 0 and false
The default value for a boolean declared at class level is false, and integer is 0;
Answer 29)
1) Compile time error
You will get an error saying something like "Cant make a static reference to a non static variable". Note that the main method is static. Even if main was not static the array argv is local to the main method and would thus not be visible within amethod.
Answer 30)
3) Output of "Not equal"
Despite the actual character strings matching, using the == operator will simply compare memory location. Because the one string was created with the new operator it will be in a different location in memory to the other string.
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Answer 31)
4) Compile and run with output of "Pausing" and "Continuing" after a key is hit
An overriden method in a sub class must not throw Exceptions not thrown in the base class. In the case of the method amethod it throws no exceptions and will thus compile without complain. There is no reason that a constructor cannot be protected.
Answer 32)
4) Compile time error because of the line creating the instance of Inner
This looks like a question about inner classes but it is also a reference to the fact that the main method is static and thus you cannot directly access a non static method. The line causing the error could be fixed by changing it to say
Inner i = new Outer().new Inner();
Then the code would compile and run producing the output "Inner"
Answer 33)
1) Error at compile time
If you implement an interface you must create bodies for all methods in that interface. This code will produce an error saying that MyWc must be declared abstract because it does not define all of the methods in WindowListener. Option 4 is nonsense as comments can appear anywhere. Option 3 suggesting that it might compile but not produce output is ment to mislead on the basis that what looks like a constructor is actually an ordinary method as it has a return type.
Answer 34)
4) Compile time error
An error will be caused by attempting to define an integer as static within a method. The lifetime of a field within a method is the duration of the running of the method. A static field exists once only for the class. An approach like this does work with Visual Basic.
Answer 35)
4)int z = 015;
The letters c and s do not exist as literal indicators and a String must be enclosed with double quotes, not single as in this case.
Answer 36)
1)double
4)instanceof
Note the upper case S on switch means it is not a keyword and the word then is part of Visual Basic but not Java . Also, instanceof looks like a method but is actually a keyword,
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Answer 37)
4) -3.0
Answer 38)
3) one
Command line parameters start from 0 and from the first parameter after the name of the compile (normally Java )
Answer 39)
4) The Set is designed for unique elements.
Collection is an interface, not a class. The Collection interface includes a method called iterator. This returns an instance of the Iterator class which has some similarities with Enumerators.
The name set should give away the purpose of the Set interface as it is analogous to the Set concept in relational databases which implies uniquness.
Answer 40)
2) If multiple listeners are added to a component the events will be processed for all but with no guarantee in the order
4) You may remove as well add listeners to a component.
It ought to be fairly intuitive that a component ought to be able to have multiple listeners. Afte [1] [2] 下一页
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