August 1999
JP219 : JAVA PROGRAMMING

QUESTION 2

Total Marks: 20 Marks

• Question 1
• Question 3
• Question 4
• Question 5
• Cover Page

SUGGESTED SOLUTIONS
Solutions and allocated marks are indicated in green.
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• A non aggregate data type;
• With utility operations which operate on that data type;
• And a strong association between the data and the operations which act upon it.

(i) member variable

(ii) method

[1]

[1]

(ii) Methods are the operations, or functions, which operate on them.

• boolean
• char
• byte
• short
• int
• long
• double
• float

(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.

[3]

[3]

[6]

public class Point{
   int x;
   int y;
}

public class VGA_Screen {
   Pixel MyScreen[65535];
}

public static void main ( ){
   int elem = 0;
   for (int a = 0; a<=255; a++) {
     for (int b=0; b<=255; b++) {
          MyScreen[elem].x=a;
          MyScreen[elem].y=b;
          elem++;
     }
   }
}