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Introducing Java Chapter Outline
I.
II.
III.
Why program in Java?
a. Java is an Object Oriented Programming language
b. Java is also a platform – can be combined like an operating system
c. Java software used to run Java applications
d. Can run on all major operating systems
Objects, Classes and Packages
a. Objects
i. Consists of related data and instructions for performing actions on that data
ii. Design for an object is a class
iii. Many objects can have the same class
b. Classes
i. Defines the type of data and actions that will be associated w/ an object of that
class, but not the actual data for an individual object
ii. Required to create objects
iii. Can create many objects
c. Packages
i. Also called a library
ii. Contains Groups of related classes
iii. Importable – can use existing classes from another package
A Java Application – package w/ at least one class that contains a main() method
a. Statements
i. Set of instructions
ii. Semicolon is required to indicate the end of a statement
iii. Related statements are enclosed by curly braces { } to begin and end the
instructions
b. Controlling Class
i. Program’s starting point
ii. Contains the main() method
c. Method
i. A named set of statements that perform a single, well defined task
ii. Public static void main (String[] args ) defines the main() method
iii. main() method is placed in the controlling class
iv. statements are automatically run when the program executes
d. Comments
i. Contained w/in the program
ii. Provide information about the program to the reader of the code
iii. Have no effect on the program
iv. Allows for easier modifications and can decrease the number of mistakes
v. 3 types of comments
1. /* */ - used to enclose single or multiline comments
2. // - used for adding a comment to the end of a statement or to create a
single line comment
3. /** */ - used for documentation
IV.
V.
VI.
Executing a Java Application
a. Code types by the programmer is source code
b. To execute or run the source code, it must be translated to code the computer
understands which is the process of compiling
c. Complied Java source code is called bytecode
i. Executing means bytecode is interpreted with the Java Virtual Machine
ii. Interpreter runs each bytecode instruction as it is read
d. Machine Code is comprised of 1’s and 0’s and is different depending on the computer
platform
e. Programs containing syntax errors will not compile
i. Syntax Error occurs in a statement that violates the rules of Java
ii. Syntax Errors keep the compiler from generating bytecode
Displaying Output
a. Output Stream
i. Sends data to an output device
ii. To display data to the standard output stream, use System.out
1. out contains print() and println() methods
b. Print() / Println()
i. print() displays data and leaves the insertion point at the end of the output
ii. println() moves the insertion point to the next line after displaying output
c. Argument
i. Data passed to a method for processing
ii. print() and println() require arguments
d. String
i. A set of characters, which are enclosed by quotation marks
ii. print() and println() arguments are strings
e. Escape Sequence
i. A backslash (\) followed by a symbol that together represents a character
ii. \n = newline
iii. \t = tab (8 spaces)
iv. \\ = backslash
v. \” = double quotation marks
Formatting Output
a. format() method can be used in place of the print() or println() methods to control the
way output is displayed
b. format() method arguments include format string and argument list
c. format string contains specifiers that indicate how the corresponding strings in the
argument list should be displayed
d. format string specifiers
i. % - indicates the start of a specifier
ii. [alignment] - skip for right alignment
1. Include a minus sign (-) for left alignment
iii. [width] – the number of characters to use for output
iv. s – indicates that the corresponding argument is a string
VII.
VIII.
Code Conventions
a. Set of guidelines for writing an application
b. Provide details about commenting, rules for naming methods, classes, packages, and
statement formatting
c. Makes code easier to read and understand
d. Code conventions in this chapter are
i. Introductory comment
1. Should include info such as your name, class, date, and brief statement
about the program
ii. Package names
1. Should begin with lowercase letter & then an uppercase letter should
begin each word within the name
2. Should not contain spaces
iii. Class names
1. Should be nouns and begin with an uppercase letter and an uppercase
letter should begin each word w/in the name
2. Should not contain spaces
iv. Comment block
1. Should be included before each class and method
2. Typically not place before the main() method
v. Comments (general)
1. Should not reiterate what is clear from the code
vi. Statements
1. Should be indented if in a method
vii. Open and Closed curly braces
1. Open curly braces { should be placed on the same line as the class or
method declaration
2. Closed curly braces } should be on a separate line and aligned with the
class or method declaration
Algorithm Design
a. A set of steps that outline how to solve a problem
b. Witten in plain English, pseudocode and or using flowcharts
i. Pseudocode is a mixture of English and program code and is useful for refining a
plain English algorithm
ii. Flowcharts use symbols and text to give a visual representation of a solution
c. Step for creating an Algorithm
i. Analyzing the problem
ii. Use more than one method to ensure accuracy