L2

1. App Design for Business
Topic: Coding Principles
Topic Number: 2

2. Key topics / learning outcomes
of this lecture
• introducing bits & bytes;
• introducing Java data types;
• introducing Java decision making;
• understanding variables;
• learn to run Java code in IntelliJ;
• introduction to xml;
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3. Computers work with bits and bytes
comprising of 1’s and 0’s.
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4. bits and bytes …
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5. Example of bits in RGB colour model
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6. RGB Colour Model - some colour
values
red green blue
255 0 0 red
0 255 0 green
0 0 255 blue
0 0 0 black
100 100 100 dark gray
255 255 255 white
255 255 0 yellow
255 0 255 magenta
160 82 45 sienna
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7. Bits and bytes are sometimes called
machine code
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8. End of introduction to bits and bytes
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9. Introduction to Data Types
Here you can see data types and how many bits
are needed for each data type:
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10. Data Types
• byte - int 127
• integer – int 2^31
• short – int 32767
• long – int 2^63-1
• float – 1.754
• double – 3.1415926 (to 754 decimal
places)
• boolean – True or False, 1 or 0
• char – a (16 bit Unicode character)
• String – String s = “This is a string”
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11. End of Data Types
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12. Introduction to Variables
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13. How variables are used in programs …
int a = 1; int b = 2; int c;
c=(a+b);
System.out.print(c);
This will print out : 3
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14. Assign different values to those
variables …
int a = 2; int b = 4; int c;
c=(a+b);
System.out.print(c);
This will print out : 6
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15. The same code in IntelliJ
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16. Change of variable values …
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17. Introducing loops to use with the variables …
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18. Introducing loops – the for loop
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19. Print a new line within the for loop
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20. Increment variable a within the loop
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21. Change variable values and multiply
instead, achieve 75 times table …
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22. How to print out in a coherent style
(note error in terminal) …
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23. Fix error, place the iterator below the
System.out …
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24. Loops – while loop
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25. Loops - introducing the do…..while
loop, compare the two …
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26. End of loops
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27. Strings
String greeting = “Hello World!”
int len = greeting.length();
char[] helloArray = { 'h', 'e', 'l', 'l', 'o', '.' };
String helloString = new String(helloArray);
System.out.println(helloString);
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28. Arraylist (slide 1 of 2)
ArrayList al = new ArrayList();
System.out.println("Initial size of al: " + al.size());
// add elements to the array list
al.add("C");
al.add("A");
al.add("E");
al.add("B");
al.add("D");
al.add("F");
al.add(1, "A2");
System.out.println("Size of al after additions: " + al.size());
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29. Arraylist (slide 2 of 2)
// display the array list
System.out.println("Contents of al: " + al);
// Remove elements from the array list
al.remove("F");
al.remove(2);
System.out.println("Size of al after deletions: " + al.size());
System.out.println("Contents of al: " + al);
}
}
This would produce the following result:
Initial size of al: 0
Size of al after additions: 7
Contents of al: [C, A2, A, E, B, D, F]
Size of al after deletions: 5
Contents of al: [C, A2, E, B, D]
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30. Arrays
// initialize first element
anArray[0] = 100;
// initialize second element
anArray[1] = 200;
// and so forth
anArray[2] = 300;
anArray[3] = 400;
anArray[4] = 500;
anArray[5] = 600;
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31. Arrays of different Data Types
• byte[ ] anArrayOfBytes;
• short[ ] anArrayOfShorts;
• long[ ] anArrayOfLongs;
• float[ ] anArrayOfFloats;
• double[ ] anArrayOfDoubles;
• boolean[ ] anArrayOfBooleans;
• char[ ] anArrayOfChars;
• String[ ] anArrayOfStrings;
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32. Java Decision Structures
if …
if ….. else if …… else
switch
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33. If ….. else if ….. else
public class Test {
public static void main(String args[]){
int x = 30;
if( x == 10 ){
System.out.print("Value of X is 10");
}else if( x == 20 ){
System.out.print("Value of X is 20");
}else if( x == 30 ){
System.out.print("Value of X is 30");
}else{
System.out.print("This is else statement");
}
}
}
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34. Use if………
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35. Introducing break; within if
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36. Introducing continue; within if
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37. Introducing switch statement
public class SwitchDemo {
public static void main(String[] args) {
int month = 8;
String monthString;
switch (month) {
case 1: monthString = "January";
break;
case 2: monthString = "February";
break;
case 3: monthString = "March";
break;
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html
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38. … the end of the Introduction to Java and
Coding Principles
… next a brief look at xml
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39. xml
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source www.w3schools.com/xml

40. xml is based on a particular xml
Schema
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source www.w3schools.com/schema

41. Essential work for next week
• Please consult the OLE for details of:
– Essential readings*
– Seminar/workshop preparation work*
– Recommended further readings
– Any additional learning
* Essential readings and preparation work must always be completed in time
for the next session
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42. End of presentation
© Pearson College 2013