CS140, TSU Introduction to Computers and Java by Li Ma
CS120 is an integrated introduction to problem solving using computers, which teaches students how real-world problems can be solved using computer programming languages
Concepts and techniques covered in CS120:
 data representation and number systems
 basic components of computer systems
 problem solving strategies
 introduction to algorithms and pseudo code
 introduction to programming languages
 introduction to operating systems
Computer systems
 hardware components o input devices, output devices, memory, CPU, ALU, secondary storage, communication devices, …
 software components o system software: operating systems, utility programs o application software
Data hierarchy

Bits: the smallest data items

Characters: a character – 1 byte – 8 bits, American Standard Code for Information
Interchange (ASCII)

Fields: a group of characters or bytes that conveys meaning
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Records: several related fields

Files: a group of related records
Computer Organization

Input unit

Output unit
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Memory unit

ALU

CPU
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CS140, TSU Introduction to Computers and Java by Li Ma

Secondary storage unit
Programming languages

Machine languages: strings of bits, slow and tedious

Assembly languages: English-like abbreviations, need too many instructions

High-level languages
Object-oriented programs are often easy to understand, correct, and modify. Objects (class objects) are essentially reusable software components in an object-oriented program
The key object-oriented programming concepts

Method : house the program statements that actually perform the tasks, but hide them from the users

Class : program unit that house the set of methods that perform the class’s tasks

Object : an instance of the class
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Reuse : a class can have many objects
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Method call : send messages to an object
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Instance variables : hold attributes of the object
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Encapsulation : classes wrap attributes and methods into objects (information hiding)
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Inheritance : the new class absorbs the characteristics of an existing class, possibly customizing them and adding unique characteristics of its own
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Polymorphism : a variable can reference objects of different types, can use the correct methods regarding to the type of the referenced object
Java is one of the object-oriented programming languages. A key goal of Java is to be able to write programs that will run on a great variety of computer systems and computer-control devices.
Java development environment:

Java SE Development Kit (JDK) for Windows

Java compiler (javac) and Java interpreter (java) on Microsoft Command Prompt

JCreator LE
Five phases to create a Java program:
1.
Edit: => source code (*.java), editor
2.
Compile: => bytecode (*.class), compiler
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CS140, TSU Introduction to Computers and Java by Li Ma
3.
Load: transfer the bytecodes to the primary memory, class loader
4.
Verify: examine the bytecodes, bytecode verifier
5.
Execute: run the bytecodes
1.
Clearly define what the program is to do
2.
Visualize the program running on the computer
3.
Use design tools such as hierarchy chart, flowcharts, or pseudocode to create a model of the program
4.
Check the model for logic errors
5.
Type the code, save it, and compile it
6.
Correct any errors found during compilation. Repeat steps 5 and 6 as many times as necessary
7.
Run the program with test data for input
8.
Correct any errors found while running the program. Repeat steps 5 through 8 as many time as necessary
9.
Validate the results of the program (output)
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