Chapter 4 - Basic Programming in Java

         Programming helps you understand the computers.

A set of rules that provides a way of telling a computer what operations to perform is called a programming language.

A program is a set of step-by-step instructions that directs the computer to do the tasks you want it to do and produce the results you want. Programmer’s job is to convert problem solutions into instructions for thecomputer.

Programmer prepares instructions of a computer program.

The programming Process

}Defining the problem

}Planning the solution

}Coding the program

}Testing the program

}Documenting the program

Symbol    Meaning

}==     Equals

}!=     Not Equal

}<     Less than

}<=     Less than or equal to

} >    Greater than

}>=     Greater than or equal to

Programming as a Career

The Joys of the Field

What It Takes  

Open Doors 

Levels of Language 

}Machine language

}Assembly languages

}High-level languages

}Very high-level languages

}Natural languages

Flowchart

is a type of diagram that represents an algorithm, workflow or process, showing the steps as boxes of various kinds, and their order by connecting them with arrows.

a picture of the separate steps of a process in sequential order.

Flowchart Basic Procedure

}Define the process to be diagrammed. Write its title at the top of the work surface.

}Discuss and decide on the boundaries of your process: Where or when does the process start? Where or when does it end? Discuss and decide on the level of detail to be included in the diagram.

}Brainstorm the activities that take place. Write each on a card or sticky note. Sequence is not important at this point, although thinking in sequence may help people remember all the steps.

Algorithm

-a procedure or formula for solving aproblem.

-a step-by-step procedure for solving aproblem.

How does it work?

Start with input  > Do complex calculations > Stop when we find the answer 

Flowchart and Pseudocode

Write a program that reads two numbers and displays the numbers in decreasing order.

Variables and Data types

          Create a program that will let the user input its name and password, if input name and password is correct end the program. If Name and password is wrong end the program.

•Variables in Java have a type.

•The type defines what kinds of values a variable is allowed to store.

•Integer Types:

–int: Most numbers you’ll deal with.

–long: Big integers; science, finance, computing.

–short: Small integers. Legacy. Not very useful.

–byte: Very small integers, useful for generic data.•Floating Point (Decimal) Types:

–float: Single-precision decimal numbers

–double: Double-precision decimal numbers.

•Other Types:

–String: Text strings.

–boolean: True or false.

–char: Latin Alphanumeric Characters

•Variable names (or identifiers) may be any length, but must start with:

–A letter (a – z),

–A dollar sign ($),

–Or, an underscore ( _ ).

•Identifiers cannot contain special operation symbols like +, -, *, /, &, %, ^, etc.

•Certain reserved keywords in the Java language are illegal.

•For example, “class”, “static”, “int”, etc.

•Java is a case-sensitive - capitalization matters.

•“Camel Case”: Start variable names with lower case and capitalize each word: “camelsHaveHumps”.

Data Type	Description
byte	Variables of this kind can have a value from: -128 to +127 and occupy 8 bits in memory
short	Variables of this kind can have a value from: -32768 to +32767 and occupy 16 bits in memory
int	Variables of this kind can have a value from: -2147483648 to +2147483647 and occupy 32 bits in memory
long	Variables of this kind can have a value from: -9223372036854775808 to +9223372036854775807 and occupy  64 bits in memory