1. Practice + Method Xiaozhong Liu
Web Programming
Practice + Method
Xiaozhong Liu

2. Read the following code:
double number;
String result;
If (number >= 5) {
result = “good” }
else {
result = “bad”
number = 5.0;
System.out.println(result);

3. Read the following code:
double salary, taxrate, income;
salary =
if (salary >= 3000) {
taxrate = 0.30; }
else {
if (salary >= 2000) {
taxrate = 0.20;
} else {
taxrate = 0.10;
income = salary * (1 - taxrate);
System.out.println(income);

4. Read the following code:
double hours, rate, salary;
String position = “manager”;
hours = 40;
If (position.equals(“manager”) || hours > 40) {
rate = 80;
} else {
If (position.equals(“employee”) || hours > 40) {
rate = 60;
rate = 40; }
salary = hours * rate

5. Read the following code:
int result, step;
step = 1;
result = 20;
While (result > 10) {
result = result – step;
if (step%2 == 0) {
step = step - 1; }
else {
step = step + 1;
System.out.println(result);
1: step = 1; result = 19
2: step = 3; result = 16
3: step = 5; result = 11
4: step = 7; result = 4

6. for (int index = 1; index < 17; index++) { total = total + 3; }
Read the following code:
int total = 0;
for (int index = 1; index < 17; index++) {
total = total + 3; }
System.out.println(total);
1: step = 1; result = 19
2: step = 3; result = 16
3: step = 5; result = 11
4: step = 7; result = 4

7. Read the following code:
Suppose IUB wants to expand student number 1.5% every year. Input the “current student number” and “years”; predict the number of students in the future (years number later).

8. What is the ideal programming style?
public static void main(String[] args) {
String query = “……”;
if (spellcorrect(query)) {
results = search(query);
results = rank(results);
show(results); }
else {
query = suggestQuery(query);
updateQuery(query);

9. Procedure public static void main(String[] args) { int number; …
ABC (number) }
Private static void ABC (int targetnum) { … }

10. Concept of Procedures and Functions
All modern programming languages have a way to break the program into smaller pieces by placing a piece of code in a procedure or function
This type of modularization is good programming design
Often entire sections of code need to be repeated in different parts of the program, for example sorting a list of data, and making it into a procedure streamlines the process
Write once, use many times
Java calls these methods

11. Method definition public static int squareR ( int y) {
scope keywords
return type
method name
formal parameter list
method
header
public static int squareR ( int y) {
// variable to hold the square of y
int ysquared;
ysquared = y * y;
return ysquared; }
method
body

12. Procedure – organize your code
public static void main(String[] args) {
String query = “???”;
String results; ……
results = search (query);
results = rank (results);
show_results(results); … }
private static String search (String query) {
String results; …
return results; }

13. Wine or water? public static void main(String[] args) { String drink;
int age = ??;
if (oldenough(age)) {
drink = “wine”; }
else {
drink = “water”;
oldenough(age)
Returns a boolean result

14. 1+2+3+4+5…100 public static void main(String[] args) { int result = 0;
int start = 1;
int end = 100;
result = sumnums (start, end);
System.out.println(result); }
sumnums (start, end)
Returns int

15. Convert temperature public static void main(String[] args) {
double Fahrenheit, Celsius = ??;
Fahrenheit = convert_temp (Celsius );
System.out.println(Fahrenheit ); }
convert_temp (Celsius )
Returns double

16. public class Example {
public double square (double x) {
x *= x;
return x; }
public static void main(String[ ] args) {
double x = 5.0;
double y = square (x);
System.out.println (x + " " + y);

17. Overload public int add (int x, int y) { ... }
public int add (int x, int y, int z) { … }
public int add (double x, double y) { ... }
same method name but different numbers or types of parameters!!
public int add (int x, int y) { ... }
public int add (int k1, int k2) { … }
WRONG!

18. Recursive method public class test {
public static int changenumber (int number) {
if (number < 0) {
return number; }
else {
number = number - 5;
return changenumber (number);
public static void main(String[] args) {
int x = changenumber (16);
System.out.println(x);

19. Practice
… 1000
… 1500
public static int sumnum (int startnum, int endnum, int intervalnum) {
int number = startnum; int result = 0;
while (number < endnum) {
result = result + number;
number = number + intervalnum; }
return result;

20. Your S517 course score?
Lab – 15%; Assignment – 45%; two exams – 40%
90-100: A; 75 – 89: B; 60 – 74: C; 45 – 60 D; 0 – 45 T.T