August
1999 QUESTION 2 Total Marks: 20 Marks |
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| (a) | One of the key features of an Object Oriented
programming language is the ability to design abstract data types.
Explain what is meant by an abstract data type.
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[3]
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| (b) | A Java class consists of member variables and
methods. Explain, with reference to your definition of an abstract data types, what is
meant by the terms (i) member variable (ii) method
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[1] [1] |
| (c) | List 3 primitive data types in the Java
programming language.
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[3] |
| (d) | A computer screen is displayed by coloring in
a set of pixels (picture elements). Each pixel can be characterized by an x coordinate and
a y coordinate. (i) Define a class, called Pixel, which represents this idea. (ii) The resolution of a VGA screen is 256 pixels by 256 pixels, giving a total of 65536 pixels. Define a class, VGA_Screen, which contains an array of pixels called MyScreen which is sufficiently large enough to represent the VGA screen. (iii) Write a main method, which is a member of your VGA_Screen class. Using two nested for loops, the method should initializes the values of the x and y values of each pixel in the array MyScreen, such that each pixel is given a unique coordinate on the screen.
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[3] [3]
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