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Java development environment and Review of Java
Java development environment and Review of Java
EclipseTM Intergrated Development Environment (IDE) Running Eclipse:
Warning: Never check the “Use this as the default and do not ask again” box.
The importance of workspace
This is where you will find all your java files. You can switch from one workspace to
another. You need to define the workspace first
(where you want to put your files) before click on OK
EclipseTM tutorial
Perspective is a set of related Views (windows)
that enable a development specialist to perform
specific tasks
Setting up preferences in Eclipse
If you did not download the JDK earlier in this tutorial, and your existing JRE does not appear in the “Installed JREs” preference, you must add it yourself.
Setting up preferences in Eclipse
Setting up preferences in Eclipse
Create an Eclipse project
From the Eclipse menu bar select File, New, Project to start the “New Project” wizard.Select “Java Project” and click “Next”.
Create an Eclipse project
Create a Java package
Structure in dot format:
for example: com.tm.tutorial.main
Create Java classes
Create Application class under com.tm.tutorial.main package
Create Java classes
Create Application class under com.tm.tutorial.main package
Implementation of Java class
Implementation of Java class
Generating setters and getters for attributes
Implementation of Java class
Generating constructors
Implementation of Java class
Generating constructors
Compile Java Application
Compile Java Application
Run the application
Run the application
Run the application
Run the application
Run Application (Shorter way)
Project 1 discussion
Algorithm for Main class
Assign a file nameAssign a file name
Create a report objectCreate a report object
Call a method from Report class to produce report from the given data file
Call a method from Report class to produce report from the given data file
Structure of Report class
Report object
-inFile
-currentBook, nextBook….
FileInputFileInput
Book
+printReport-processBook-processGenre-columnHeadings-padL-padR
Datamembers
Methods
Algorithm for printing a report (Report.java)
Open fileOpen file
Printing headingPrinting heading
Read a recordRead a record
processing genre*processing genre*
Print footer of the report
Print footer of the report
Record != null ?Record != null ?
true
false
Algorithm for process a book and a genre
currentBook = record just readCurrent genre = genre of the current book
currentBook = record just readCurrent genre = genre of the current book
Print information about a bookPrint information about a book
Read another bookRead another book
Total price for each genre += price of the current book
Total price for each genre += price of the current book
Start a new genre and go back to processing a new genre
Start a new genre and go back to processing a new genre
Is another book has the same genre ?
Is another book has the same genre ?
true
false
Class exercise
Class Object Primitive Data Type If, Switch While, Do-While
Review of Java fundamentalsTemplate for Class Definition
class {
}
Import StatementsImport Statements
Class CommentClass Comment
Class NameClass Name
Data MembersData Members
Methods(incl. Constructor)
Methods(incl. Constructor)
Review of Java fundamentalsTemplate for Class Definition
class {
}
Import StatementsImport Statements
Class CommentClass Comment
Class NameClass Name
Data MembersData Members
Methods(incl. Constructor)
Methods(incl. Constructor)
Numeric data
Variable declaration:
<data type> <variable_name>;
If more than one variable has the same data type:
<data type> <name1>, <name2>..;
Six numerical data types
byte: -128 to 127 short:-32768 to 32767 (-215 to 215-1) int: -231 to 231-1 long: -263 to 263-1 float: -3.4E+38 to 3.4E+38 double:-1.797E+308 to 1.797E+308
Assignment statement
<variable name> = <expression>;
Example:
x =2*5+6-1;
Variable names
It must be a legal identifier which is an unlimited series of characters that begins with a letter.
It must not be a keyword, a boolean literal (true or false), or the reserved word null.
It must be unique within its scope.
Variable name (cont.)
Legal identifier:be composed of letters, numbers, _ and $. Identifiers may only begin with a letter, _, or $.
Keyword:
http://java.sun.com/docs/books/tutorial/java/nutsandbolts/_keywords.html
Variable names begin with a lowercase letter Class names begin with an uppercase letter
Constant and variables
Constant: Value it contains doesn’t change
final int MONTHS_IN_YEAR = 12;
Variables: Value it contains may vary
double loanAmount; loanAmount =0; loanAmount = 1000.99;
Integer division and type casting Integer division:
Integer/integer = integer, 7/2 = 3 Integer/double = double, 7/2.0 = 3.5 Double/integer = double, 7.0/2 = 3.5
Type casting: a process that converts a value of one data type to another data type.
Implicit casting
Explicit casting
Type casting (cont.)
Implicit casting: Operand is converted from a lower to a higher
precision Higher precision: a data type with a larger range
of values Double has a higher precision than float Int has a higher precision than short
Operand: can be a constant, variable, method call or another arithmetic expression
Type casting (cont.)
Explicit casting (<data type>) <expression> Example:
float result;
result = (float) ((3+5)/6);
and
result = ((float) (5+3))/6;
if (<boolean expression>) <block>;else <block>;
Simple Choice Statement
if (<boolean expression>) single statement;else single statement;
Boolean expression
Boolean expression: is a conditional expression that is evaluated to either true or false.
Conditional expression: is a three part expression:<exp.> <relational operators><exp.>
Boolean expressions can be combined by boolean operators
Relational Operators
Expression Meaninga == b Is a equal to b?a != b Is a not equal to b?a > b Is a greater than b?a < b Is a less than b?a >= b Is a greater than or equal to b?a <= b Is a less than or equal to b?
Boolean operators
&& means AND
|| means OR
! means NOT
The While Loop
while(<boolean expression>){
// Repeat multiple statements.
statement 1
statement 2
statement 3
...
}
The Do Loopdo{ // Repeat multiple statements. statement 1 statement 2 statement 3 ...} while(<boolean expression);
•Note that the statements in the body of the loop are always executed at least one.•Note the final semicolon, which is required.
The For-Loop Outline// Repeat multiple statements.for(initialization; condition; post-body update){ // Statements to be repeated. statement 1 statement 2 statement 3 ...}
•Commonly used with increment and decrement operators.
Increment and Decrement Used as a shorthand for add-one-to and
subtract-one-from: value = value+1; value += 1; value++;
Prefix and postfix forms: ++value; --value; value--;
Attributes (Data Member) Declaration
<modifiers> <data type> <name> ;
private String ownerName ;
ModifiersModifiers Data TypeData Type NameName
Note: There’s only one modifier in this example.
Note: There’s only one modifier in this example.
Method Declaration
<modifier> <return type> <method name> ( <parameters> ){
<statements>
}
public void setOwnerName ( String name ) {
ownerName = name;
}
StatementsStatements
ModifierModifier Return TypeReturn Type Method NameMethod Name ParameterParameter
Constructor A constructor is a special method that is executed when a new
instance of the class is created.
public <class name> ( <parameters> ){ <statements> }
public Bicycle ( ) {
ownerName = “Unassigned”;
}StatementsStatements
ModifierModifier Class NameClass Name ParameterParameter
Arguments and Parameters
An argument is a value we pass to a method. A parameter is a placeholder in the called method to
hold the value of the passed argument.
class Account {
. . .
public void add(double amt) {
balance = balance + amt; }
. . . }
class Sample {
public static void main(String[] arg) { Account acct = new Account(); . . . acct.add(400); . . . }
. . . } argument
Arguments and Parameters
An argument is a value we pass to a method. A parameter is a placeholder in the called method to
hold the value of the passed argument.
class Account {
. . .
public void add(double amt) {
balance = balance + amt; }
. . . }
class Sample {
public static void main(String[] arg) { Account acct = new Account(); . . . acct.add(400); . . . }
. . . }
parameter
Algorithm for Main class
Assign a file nameAssign a file name
Create a report objectCreate a report object
Call a method from Report class to produce report from the given data file
Call a method from Report class to produce report from the given data file
Algorithm for printing a report (Report.java)
Open fileOpen file
Printing headingPrinting heading
Read a recordRead a record
processing a movie*processing a movie*
Print footer of the report
Print footer of the report
Record != null ?Record != null ?
true
false
Algorithm for process a movie and a genre
currentMovie = record just readCurrent genre = genre of the current movie
currentMovie = record just readCurrent genre = genre of the current movie
Print information about a moviePrint information about a movie
Read another movieRead another movie
Total price for each genre += price of the current movie
Total price for each genre += price of the current movie
Start a new genre and go back to processing a new genre
Start a new genre and go back to processing a new genre
Is another movie has the same genre ?
Is another movie has the same genre ?
true
false
