1
Java Syntax
COP3330 – Fall 2006
University of Central Florida
H. Schwartz
Outline
• Classes and Methods
• Primitives and Variables
• Strings
• Input and Output
• Modifiers
• Control Structures
• Constructors
COP 3330 – Fall 2006
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Java Syntax: COP3330 Fall 2006 University of Central Florida, Study Guides, Projects, Research of Computer Science
An outline for the java syntax course cop3330 offered at the university of central florida in fall 2006. Topics covered include classes and methods, primitives and variables, strings, input and output, modifiers, control structures, constructors, and more. Students will learn the basics of java programming through lectures and exercises.
Typology: Study Guides, Projects, Research
Pre 2010
1 / 18
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Java Syntax: COP3330 Fall 2006 University of Central Florida and more Study Guides, Projects, Research Computer Science in PDF only on Docsity!
Java Syntax
COP3330 – Fall 2006
University of Central Florida
H. Schwartz
Outline
• Classes and Methods
• Primitives and Variables
• Strings
• Input and Output
• Modifiers
• Control Structures
• Constructors
COP 3330 – Fall 2006
Classes and Methods
• Comments:
• Represent: Always include name, NID, COP3330,
project title, and date.
Java Syntax - COP 3330 – Fall 2006
// place two slashes before line comments
/* this is block comment style
everything between the slash-star and star-slash
is considered a comment and ignored by the
compiler.
Classes and Methods
• a class
Java Syntax - COP 3330 – Fall 2006
class FirstClassExample {
//class definition here
//notice the capitalization
public class FirstClassExample {
//class definition here
//notice the capitalization
Tangent:
Java and long
names
Classes and Methods
• Constructing an object out of a
class:
Java Syntax - COP 3330 – Fall 2006
public static void main (String [] args) {
//main method for class
//Construct a FirstClassExample object named “example”:
FirstClassExample example = new FirstClassExample();
Primitives and Variables
• Variables hold anything that can change (vary) during
execution.
= ;
• Objects can be assigned to variables.
Java Syntax - COP 3330 – Fall 2006
Primitives and Variables
• Java has a finite set of primitives:
• Primitives are not treated as objects
Java Syntax - COP 3330 – Fall 2006
NA boolean true, false false 1 bit used in 32 bit integer
Unicode character \u0000 16 bits \u0000 to \uFFFF char
+/-4.9E-324 to
+/-1.7976931348623157E+308,
+/-infinity, +/-0, NaN
double IEEE 754 floating point 0.0 64 bits
+/-1.4E-45 to +/-3.4028235E+38,
+/-infinity, +/-0, NaN
float IEEE 754 floating point 0.0 32 bits
-9223372036854775808 to
9223372036854775807
long signed integers 0 64 bits
int signed integers 0 32 bits -2147483648 to 2147483647
short signed integers 0 16 bits -32768 to 32767
-128 to 127 byte signed integers 0 8 bits
Type Values Default Size Range
Primitives and Variables
• Arithmetic Operators
– Standard syntax, Examples:
• Increment and Decrement
Java Syntax - COP 3330 – Fall 2006
x = y + z;
z = x * y;
int x = y – z;
z = x * (y + u) / a;
z = 2 * (10 + 12) / 4; //z = 2 * 22 = 44 / 4 = 11
x++; //same as x = x + 1, original x returned as value
x--; //same as x = x - 1, original x returned as value
++x; //same as x = x + 1, original x + 1 returned as value
x += 5; //same as x = x + 5
x -= 3; //same as x = x - 3
Input and Output
• Output
– System.out class member
– (System is class, out is object)
- Common Methods:
- println
Java Syntax - COP 3330 – Fall 2006
String sentence = “I love OOP”;
System.out.print(sentence);//no new line at the end
System.out.println(sentence);//new line at the end
System.out.println(“Who would actually say:\n” + sentence);
//use \n to put newline in middle, append sentence to end
Input and Output
• Input
– Scanner class:
– Scanner objects help extract values from the standard input.
Java Syntax - COP 3330 – Fall 2006
import java.util.;//Scanner is part of java.util.
Scanner stdin = new Scanner(System.in);
Input and Output
• Input
– Scanner methods
– A token is (generally) something separated by whitespace.
Java Syntax - COP 3330 – Fall 2006
Scanner stdin = new Scanner(System.in);
double aReal = stdin.nextDouble();//get a double from the input stream
int anInt = stdin.nextInt();//gets an int
String aString = stdin.next();//gets the next input as a String
String line = stdin.nextLine();//gets a whole line as a String
Modifiers
Statement list
}
• Choices:
– public/private/protected
– static
– final
– abstract
Java Syntax - COP 3330 – Fall 2006
Classes and Objects Revisited
• Instance Variables
Java Syntax - COP 3330 – Fall 2006
public class ClassWithInstanceVariables{
int number;
String name;
public ClassWithInstanceVariables(){
//constructor: sets initial values
this.number = 0;
this.name = “unknown”;
public void incrementPrintNum(){
//increments number and prints it’s original and new values
int oldNum = number;
this.number++;
System.out.print(oldNum + “, “ + this.number);
Methods Revisited
• Return values
– Standard syntax
Java Syntax - COP 3330 – Fall 2006
public int getNum() {
//returns an integer after doing something
int x = 5;
return x;
Methods Revisited
• Parameters..
Java Syntax - COP 3330 – Fall 2006
public int setNum(int n){
//sets instance variable number to n
this.number = n;
Public int setNumName(int n, String name){
//sets number and name
this.number = n;
this.name = name; //notice same variables name (this is important)
Operators revisited
• Integer Division ‘/’
– Everything after decimal truncated
• Modulo ‘%’
- Remainder of division
Java Syntax - COP 3330 – Fall 2006
Operators revisited
• Overflow and Underflow
- Value of result can not be stored in desired primitive type
- Inaccurate result produced
Java Syntax - COP 3330 – Fall 2006
int biggestInt = Integer.MAX_VALUE;
System.out.println(biggestInt+1);
Control Structures
• Boolean operators
- return true or false
- (p && q) (p || q)
- !p
- (p == q) (p != q)
- (p > q) (p >= q) (p < q) (p <= q)
Java Syntax - COP 3330 – Fall 2006
Control Structures
• if statement
• if ()
Java Syntax - COP 3330 – Fall 2006
int a = 10;
int b = 12;
if (a < b)
a++;
if (a >= b) {
a++;
b = a – 1;
Control Structures
• if else statement
if ()
else
Java Syntax - COP 3330 – Fall 2006
int a = 10;
int b = 12;
if (a < b)
a++;
else {
a++;
b = a – 1;
Control Structures
• for (; ; )
Java Syntax - COP 3330 – Fall 2006
for (int i = 0; i < 50; i++){
//prints 0 through 49
System.out.println(“I is ” + i);
Control Structures
• Nested Control Structures
- Placing control structures within other structures
Java Syntax - COP 3330 – Fall 2006
int sum = 0;
for (int i = 0; i < 50; i++){
//takes the sum of factorials
int mult = 1;
for (int j = i; j > 0; j--){
//finds i factorial
mult = mult * j;
sum = sum + mult;
String location = house.getLoc();
if (location.equals(“orlando”)){
//decision to buy a house
int price = house.getPrice;
if (price < 100000)
house.buy();
else if (price < 120000)
house.bargain();
else
house.moveOn();
Constructors Revisited
• Multiple Constructors
- Initialize different variables, or take in different parameters.
Java Syntax - COP 3330 – Fall 2006
String name;
int gpa;
public Student(String name, int gpa){
//constructor for all parameters
this.name = name;
this.gpa = gpa;
public Student(String name){
//constructor for name only
this.name = name;
this.gpa = 0;//don’t know gpa
More on objects
• Object Variable is a reference to an
object
– default value: null
– assignment operator copies location
– objects as parameters: passes location
Java Syntax - COP 3330 – Fall 2006