Answers
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Answer 1)
Objective 1.2)
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.
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Answer 2)
Objective 4.1)
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
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Answer 3)
Objective 4.3)
1) public2) private4) 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.
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Answer 4)
Objective 1.2)
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
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Answer 5)
Objective 1.2)
1) To get to access hardware that Java does not know about3) To write
optimised code for performance in a language such as C/C++
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Answer 6)
Objective 1.2)
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.
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Answer 7)
Objective 1.2)
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 8)
Objective 1.2)
1)Compile time error: Base cannot be private
A top leve (non nested) class cannot be private.
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Answer 9)
Objective 1.2)
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.
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Answer 10)
Objective 1.1)
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.
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Answer 11)
Objective 1.1)
2)myarray.length;
The String class has a length() method to return the number of characters. I
have sometimes become confused between the two.
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Answer 12)
Objective 8.2)
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.
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Answer 13)
Objective 8.2)
4) Do nothing, the FlowLayout will position the component
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Answer 14)
Objective 8.2)
1) Use the setLayout method
Answer 15)
Objective 8.2)
1) ipadx2) fill3) insets
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Answer 16)
Objective 8.2)
2) The buttons will run from left to right along the top of the
frameThe 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.
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Answer 17)
Objective 8.2)
2) It is a field of the GridBagConstraints class for controlling component
placement3) A valid settting for the anchor field is
GridBagconstraints.NORTH
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Answer 18)
Objective 7.1)
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 calledpublic 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.
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Answer 19)
Objective 8.2)
2) falseYou can re-use the same instance of the GridBagConstraints
when added successive components.
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Answer 20)
Objective 10.1)
4) An interface that ensures that implementing classes cannot contain
duplicates
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