Fundamentals of Java Text by Lambert and Osborne

Fundamentals of Java Text by: Lambert and Osborne

Unit 1 Getting Started with Java Lesson 1: Background

Lesson 1: Background Objectives: Ø Give a brief history of computers. Ø Describe how hardware and software make up computer architecture. Ø Understand the binary representation of data and programs in computers. Ø Discuss the evolution of programming languages. Ø Describe the software development process. Ø Discuss the fundamental concepts of objectoriented programming.

Lesson 1: Background o o o Vocabulary: Application software Assembly language Auxiliary input/output devices Auxiliary storage devices Bit Byte Central processing unit (CPU) Hardware Information hiding Instance variables Internal memory Machine language

Lesson 1: Background o o o Vocabulary (continued): Network connection Object-oriented programming Primary memory RAM ROM Secondary memory Software development life cycle (SDLC) System software Ubiquitous computing User interface Waterfall model

1. 1 History of Computers • 1940 s: The ENIAC was one of the world’s first computers. üLarge stand-alone machine üUsed large amounts of electricity üContained miles of wires and thousands of vacuum tubes üConsidered immensely useful when compared to hand-operated calculators

1. 1 History of Computers • 1950 s: IBM sold its first business computer. üComputational power was equivalent to 1/800 of a typical 800 -megahertz Pentium computer sold in 2000 ü 1/2000 of the computing power of today’s laptops üPerformed one task at a time üTypical input and output devices were punch cards and paper tape

1. 1 History of Computers • 1960 s: Expensive time-sharing computers became popular in large organizations that could afford them. ü 30 people could work on one computer simultaneously üInput occurs via teletype machine üOutput is printed on a roll of paper üCould be connected to the telephone

1. 1 History of Computers • 1970 s: The advantages of computer networks was realized. üEmail and file transfers were born • 1980 s: PCs became available in large numbers. üNetworks of interconnected PCs became popular (LANs) üOrganizations utilized resource and file sharing

1. 1 History of Computers • 1990 s: An explosion of computer use occurs. üHundreds of millions of computers are being used in businesses and homes üMost computers are now connected to the Internet üJava is quickly becoming the common language of today’s computers üComputing has become ubiquitous. – Cell phones, cameras, PDAs, music player

1. 2 Computer Hardware and Software Computers consist of two primary components: 1. Hardware Physical devices that you see on your desktop 2. Software Programs that give hardware useful functionality

1. 2 Computer Hardware and Software • Hardware – A bit (or binary digit) • • The smallest unit of information processed by a computer Consists of a single 0 or 1 – Bytes • • Consists of 8 adjacent bits The capacity of computer memory and storage devices is usually expressed in bytes

1. 2 Computer Hardware and Software Hardware – As illustrated in figure 1 -2, a PC consists of six major subsystems 1. 2. 3. 4. 5. User interface Auxiliary I/O devices - keyboard, monitor, printer, etc. Auxiliary storage devices - flash memory, DVDs, etc. Network connection - Modem, Ethernet cards Internal memory – RAM - random access memory – ROM - read only memory 6. Central processing unit - Performs basic tasks of the computer – Moore’s Law: Speed doubles every 2 years –Transistors are the building blocks of CPU and RAM

1. 2 Computer Hardware and Software

1. 2 Computer Hardware and Software • Computer software processes complex patterns of 0 s and 1 s and transforms them to be viewed as text, images, etc.

1. 2 Computer Hardware and Software Two broad categories of software: 1. System Software: • • supports the basic operations of a computer allows users to transfer information to and from the computer • Examples: OS, Compilers, Communications Software, User Interface Subsystem 2. Application Software: • allows users to accomplish specialized tasks • Examples: Word Processors, Spreadsheets, Database systems, Other programs we write

1. 2 Computer Hardware and Software Commonly used terms to describe storage

1. 3 Binary Representation of Information and Computer Memory ★ Examine how different types of information are represented in binary notation. § § § § Integers Floating Point Numbers Characters and Strings Images Sound Program Instructions Computer Memory

1. 3 Binary Representation of Information and Computer Memory Computer memory stores patterns of electronic signals. ★ The patterns are strings of binary digits or bits. ★ Computers use binary (base 2) notation. ➡ Two bases: On/Off ➡ Computer scientists also use bases octal (8) ➡ and hexadecimal (16).

1. 3 Binary Representation of Information and Computer Memory • Example: Analyze the meaning of 100112, where the subscript 2 indicates that base 2 is being used

1. 3 Binary Representation of Information and Computer Memory • Table 1 -1 shows some base 10 numbers and their base 2 equivalents.

1. 3 Binary Representation of Information and Computer Memory • Table 1 -2 displays some characters and their corresponding ASCII bit patterns.

1. 3 Binary Representation of Information and Computer Memory • Java uses Unicode Patterns of 15 bits from 0000 to 1111

1. 3 Binary Representation of Information and Computer Memory Sound is analog data. ➡Analog information has a continuous range of infinite values. ➡Sampling reads the waveform at intervals. ➡Memory requirements for sound are higher than text. ✓Images ➡Sampling measures color values as pixels in a twodimensional grid. ➡Grayscale, black-and-white, RGB, true-color

1. 3 Binary Representation of Information and Computer Memory Video ➡Video includes a soundtrack and a set of images called frames. ➡Data compression is difficult. ✓Program instructions ➡A sequence of bits in RAM ✓Computer Memory ➡A gigantic sequence of bytes, each with an address.

1. 3 Binary Representation of Information and Computer Memory • Java uses Unicode Patterns of 15 bits from 0000 to 1111

1. 4 Programming Languages • Generation 1 – Late 1940 s to Early 1950 s: Machine Languages Ø Programmers entered programs and data directly into RAM using 1 s and 0 s Ø Several disadvantages existed: Ø Coding was error prone, tedious, and slow Ø Modifying programs was extremely difficult Ø It was nearly impossible for a person to decipher someone else’s program Ø Programs were not portable Ø Each type had its own machine language

1. 4 Programming Languages Ø Generation 2 – Early 1950 s to Present: Assembly Languages Ø Uses mnemonic symbols to represent instructions and data Ø Assembly language is: Ø More programmer friendly than machine language Ø Tedious to use and difficult to modify Ø Since each type of computer has its own unique assembly language, it is not portable Ø Programs are translated by assembler and loaded and run using a loader. Ø Assembly language is more programmer friendly, but still tedious.

1. 4 Programming Languages Ø Generation 3 – Mid-1950 s to Present: High. Level Languages Ø Designed to be human friendly – easy to read, write, and understand Ø Each instruction corresponds to many instructions in machine language Ø Translation to machine language occurs through a program called a ‘compiler’ Ø Examples: FORTRAN, COBOL, BASIC, C, Pascal, C++, Smalltalk, Python, and Java Ø Java does not need to be recompiled for each type of computer.

1. 5 The Software Development Process v Creating high-quality software involves organization, planning and utilizing various diagrammatic conventions v Computer scientists have created a view of the software development process known as the ‘software development life cycle’ (SDLC) v One method is known as the ‘waterfall model’’ v A mistake made in one phase often requires the developer to back up and redo some of the work in the previous phase

1. 5 The Software Development Process v The Waterfall Model consists of several phases: v Customer Request v Analysis v Design v Implementation v Integration v Maintenance

1. 5 The Software Development Process v Figure 1 -6. The waterfall model of the software development life cycle.

1. 5 The Software Development Process v Mistakes found early in the SDLC are much less expensive to correct than those found late.

1. 5 The Software Development Process v The cost of developing software is not spread equally over the phases. The percentages shown in Figure 16 are typical.

1. 6 Basic Concepts of Object-Oriented Programming ü High-level programming languages utilize two different approaches ü Procedural approach ü Examples: COBOL, FORTRAN, BASIC, C and Pascal ü Object-oriented approach - Superior approach ü Examples: Smalltalk, C++, Python, and Java

1. 6 Basic Concepts of Object-Oriented Programming ü Object-oriented programming (OOP) involves: ü Planning ü Determine your needs ü Create a list of necessary resources ü Establish the rule of behavior to be followed ü Execution ü Outcome ü Classes define: ✓ Instance variables (data resources) ✓ Methods (rules of behavior) ✓ Combining resources and behaviors into a single software entity is encapsulation

1. 6 Basic Concepts of Object-Oriented Programming ü Classes are organized into hierarchies. ü Subclasses share methods and instance variables with the root class using inheritance. ü Different types of objects can understand the same message, called polymorphism. ü An object’s response to a message depends on its class.

1. 6 Basic Concepts of Object-Oriented Programming ü The Expedition analogy to OOP

1. 6 Basic Concepts of Object-Oriented Programming ü The Expedition analogy to OOP

1. 6 Basic Concepts of Object-Oriented Programming In this chapter, you learned: üThe modern computer age began in the late 1940 s with the development of ENIAC. Business computing became practical in the 1950 s, and time-sharing computers advanced computing in large organizations in the 1960 s and 1970 s. The 1980 s saw the development and first widespread sales of personal computers, and the 1990 s saw personal computers connected in networks. During the first decade of the twenty-first century, computing has become ubiquitous.

1. 6 Basic Concepts of Object-Oriented Programming ✓Modern computers consist of two primary components: hardware and software. Computer hardware is the physical component of the system. Computer software consists of programs that enable us to use the hardware. ✓All information used by a computer is represented in binary form. This information includes numbers, text, images, sound, and program instructions.

1. 6 Basic Concepts of Object-Oriented Programming ✓Programming languages have been developed over the course of three generations: generation 1 is machine language, generation 2 is assembly language, and generation 3 is high-level language. ✓The waterfall model of the software development process consists of several standard phases: customer request, analysis, design, implementation, integration, and maintenance

1. 6 Basic Concepts of Object-Oriented Programming ✓Object-oriented programming is a style of programming that can lead to better-quality software. Breaking code into easily handled components simplifies the job of writing a large program.

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