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Chapter 1 Introduction to Computers, Programs, and Java Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 1  Objectives  To understand comp...

Chapter 1 Introduction to Computers, Programs, and Java Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 1  Objectives  To understand computer basics, programs, and operating systems (§§1.2–1.4).  To describe the relationship between Java and the World Wide Web (§1.5).  To understand the meaning of Java language specification, API, JDK, and IDE (§1.6).  To write a simple Java program (§1.7).  To display output on the console (§1.7).  To explain the basic syntax of a Java program (§1.7).  To create, compile, and run Java programs (§1.8).  To use sound Java programming style and document programs properly (§1.9).  To explain the differences between syntax errors, runtime errors, and logic errors (§1.10).  To develop Java programs using NetBeans (§1.11).  To develop Java programs using Eclipse (§1.12). Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 2 What is a Computer? A computer consists of a CPU, memory, hard disk, floppy disk, monitor, and communication devices. Bus Storage Communication Input Output Devices Memory CPU Devices Devices Devices e.g., Disk, CD, e.g., Modem, e.g., Keyboard, e.g., Monitor, and Tape and NIC Mouse Printer Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 3  CPU The central processing unit (CPU) is the brain of a computer. It retrieves instructions from memory and executes them. Its speed is measured in megahertz (MHz), with 1 megahertz equaling 1 million pulses per second. The speed of the CPU has been improved continuously. If you buy a PC now, you can get a Processor at 8 gigahertz. Bus Storage Communication Input Output Memory CPU Devices Devices Devices Devices e.g., Disk, CD, e.g., Modem, e.g., Keyboard, e.g., Monitor, and Tape and NIC Mouse Printer Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 4  Memory Memory is to store data and program instructions for CPU to execute. A memory unit is an ordered sequence of bytes, each holds eight bits. A program and its data must be brought to memory before they can be executed. A memory byte is never empty, but its initial content may be meaningless to your program. The current content of a memory byte is lost whenever new information is placed in it. Bus Storage Communication Input Output Memory CPU Devices Devices Devices Devices e.g., Disk, CD, e.g., Modem, e.g., Keyboard, e.g., Monitor, and Tape and NIC Mouse Printer Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 5  How Data is Stored? Data of various kinds, such as numbers, and characters are encoded as a series of bits (0 and 1). Computers use 0 and 1 because digital devices have two stable states, which are referred to as 0 and 1 by convention. Programmers do not bother about the encoding and decoding of data. It is performed automatically by the system based on the encoding scheme. For example, character ‘J’ is represented by 01001010 in one byte. If computer needs to store a large number that cannot fit into a single byte, it uses a number of adjacent bytes. No two data can share or split a same byte. A byte is the minimum storage unit. Memory address Memory content...... 2000 01001010 Encoding for character ‘J’ 2001 01100001 Encoding for character ‘a’ 2002 01110110 Encoding for character ‘v’ 2003 01100001 Encoding for character ‘a’ 2004 00000011 Encoding for number 3 Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 6  Storage Devices Memory such RAM is volatile. Programs and data are permanently stored on storage devices and are moved to memory when the computer actually uses them. There are three main types of storage devices:Disk drives (hard disks and floppy disks), CD drives (CD-R and CD-RW), and Tape drives. Bus Storage Communication Input Output Memory CPU Devices Devices Devices Devices e.g., Disk, CD, e.g., Modem, e.g., Keyboard, e.g., Monitor, and Tape and NIC Mouse Printer Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 7  Output Devices: Monitor The monitor displays information (text and graphics). The resolution and dot pitch [distance between pixels] determine the quality of the display. Bus Storage Communication Input Output Memory CPU Devices Devices Devices Devices e.g., Disk, CD, e.g., Modem, e.g., Keyboard, e.g., Monitor, and Tape and NIC Mouse Printer Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 8  Monitor Resolution and Dot Pitch resolution The screen resolution specifies the number of pixels in horizontal and vertical dimensions of the display device. Pixels (short for “picture elements”) are tiny dots that form an image on the screen. A common resolution for a 17-inch screen, for example, is 1,024 pixels wide and 768 pixels high. The resolution can be set manually. The higher the resolution, the sharper and clearer the image is. dot pitch The dot pitch is the amount of space between pixels, measured in millimeters. The smaller the dot pitch, the sharper the display. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 9  Communication Devices A regular modem, uses a phone line, can transfer data in a speed up to 56,000 bps (bits per second). A DSL (digital subscriber line) also uses a phone line and can transfer data in a speed 20 times faster than a regular modem. A cable modem uses the TV cable line maintained by the cable company. A cable modem is as fast as a DSL. Network Interface Card (NIC) is a device to connect a computer to a local area network (LAN). A NIC, called 10BaseT, can transfer data at 10 mbps (million bits per second). Bluetooth devices Bus Infrared devices Storage Communication Input Output Modem (over phone line) Devices Memory CPU Devices Devices Devices e.g., Monitor, Network card (using Ethernet) e.g., Disk, CD, and Tape e.g., Modem, and NIC e.g., Keyboard, Mouse Printer Smartphone Wi-Fi devices (using a Wi-Fi router) Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 10  Programs Computer programs, known as software, are instructions to the computer. You tell a computer what to do through programs. Without programs, a computer is an empty machine. Computers do not understand human languages, so you need to use computer languages to communicate with them. Programs are written using programming languages. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 11  Programming Languages Machine Language Assembly Language High-Level Language Machine language is a set of primitive instructions built into every computer. The instructions are in the form of binary code, so you have to enter binary codes for various instructions. Program with native machine language is a tedious process. Moreover the programs are highly difficult to read and modify. For example, to add two numbers, you might write an instruction in binary like this: 1 + 2. MOV AX, 1 B8 (MOV immediate to AX register) 01 00 (value 1) ADD AX, 2  83 (ADD with an immediate value) C0 to the AX register 02 (value 2) Imagine if you have such program. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 12  Programming Languages Machine Language Assembly Language High-Level Language Assembly languages were developed to make programming easy. Since the computer cannot understand assembly language, however, a program called assembler is used to convert assembly language programs into machine code. For example, to add two numbers, you might write an instruction in assembly code like this: ADDF3 R1, R2, R3 Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 13  Programming Languages Machine Language Assembly Language High-Level Language The high-level languages are English-like and easy to learn and program. For example, the following is a high-level language statement that computes the area of a circle with radius 5: area = 5 * 5 * 3.1415; Ada Named for Ada Lovelace, who worked on mechanical general-purpose computers. The Ada language was developed for the Department of Defense and is used mainly in defense projects. BASIC Beginner’s All-purpose Symbolic Instruction Code. It was designed to be learned and used easily by beginners. C Developed at Bell Laboratories. C combines the power of an assembly language with the ease of use and portability of a high-level language. C++ C++ is an object-oriented language, based on C. C# Pronounced “C Sharp.” It is a hybrid of Java and C++ and was developed by Microsoft. COBOL COmmon Business Oriented Language. Used for business applications. FORTRAN FORmula TRANslation. Popular for scientific and mathematical applications. Java Developed by Sun Microsystems, now part of Oracle. It is widely used for developing platform-independent Internet applications. Pascal Named for Blaise Pascal, who pioneered calculating machines in the seventeenth century. It is a simple, structured, general-purpose language primarily for teaching programming. Python A simple general-purpose scripting language good for writing short programs. Visual Basic Visual Basic was developed by Microsoft and it enables the programmers to rapidly develop graphical user interfaces. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 14  Interpreting/Compiling Source Code A program written in a high-level language is called a source program or source code. Because a computer cannot understand a source program, a source program must be translated into machine code for execution. The translation can be done using another programming tool called an interpreter or a compiler. Interpreting Source Code An interpreter reads one statement from the source code, translates it to the machine code or virtual machine code, and then executes it right away, as shown in the following figure [i.e Matlab]. Note that a statement from the source code may be translated into several machine instructions. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 15  Compiling Source Code A compiler [C and C++] translates the entire source code into a machine- code file, and the machine-code file is then executed, as shown in the following figure. Java can be considered both a compiled and an interpreted language because its source code is first compiled into a binary byte-code. This byte-code runs on the Java Virtual Machine (JVM), which is usually a software-based interpreter. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 16  Operating Systems The operating system (OS) is a program that manages and controls a computer’s activities. The popular operating systems for general- purpose computers are Microsoft Windows, Mac OS, and Linux. Application programs, such as a Web browser or a word processor, cannot run unless an operating system is installed and running on the computer. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 17  Why Java? Java enables users to develop and deploy applications on the Internet for servers, desktop computers, and small hand-held devices. The future of computing is being profoundly influenced by the Internet, and Java promises to remain a big part of that future. Java is the Internet programming language. Java is a general purpose programming language. Java is the Internet programming language. Java, Web, and Beyond  Java can be used to develop standalone applications.  Java can be used to develop applications running from a browser.  Java can also be used to develop applications for hand-held devices.  Java can be used to develop applications for Web servers. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 18  Java’s History  James Gosling and Sun Microsystems  Oak  Java, May 20, 1995, Sun World  HotJava – The first Java-enabled Web browser  Early History Website: http://www.java.com/en/javahistory/index.jsp Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 19 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable  Java's Performance  Java Is Multithreaded  Java Is Dynamic www.cs.armstrong.edu/liang/JavaCharacteristics.pdf Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 20 Companion Website Characteristics of Java  Java Is Simple Java is partially modeled on C++, but greatly simplified and improved. Some people refer to  Java Is Object-Oriented Java as "C++" because it is like C++ but with  Java Is Distributed more functionality and fewer negative aspects.  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable  Java's Performance  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 21 Companion Website Characteristics of Java  Java Is Simple Java is inherently object-oriented. Although many object-oriented languages  Java Is Object-Oriented began strictly as procedural languages,  Java Is Distributed Java was designed from the start to be object-oriented. Object-oriented  Java Is Interpreted programming (OOP) is a popular  Java Is Robust programming approach that is replacing  Java Is Secure traditional procedural programming techniques.  Java Is Architecture-Neutral  Java Is Portable One of the central issues in software development is how to reuse code. Object-  Java's Performance oriented programming provides great  Java Is Multithreaded flexibility, modularity, clarity, and reusability through encapsulation,  Java Is Dynamic inheritance, and polymorphism. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 22 Companion Website Characteristics of Java  Java Is Simple Distributed computing involves several computers working together on a network.  Java Is Object-Oriented Java is designed to make distributed  Java Is Distributed computing easy. Since networking capability is inherently integrated into  Java Is Interpreted Java, writing network programs is like  Java Is Robust sending and receiving data to and from a  Java Is Secure file.  Java Is Architecture-Neutral  Java Is Portable  Java's Performance  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 23 Companion Website Characteristics of Java  Java Is Simple You need an interpreter to run Java programs. The programs are compiled into  Java Is Object-Oriented the Java Virtual Machine code called  Java Is Distributed bytecode. The bytecode is machine- independent and can run on any machine  Java Is Interpreted that has a Java interpreter, which is part of  Java Is Robust the Java Virtual Machine (JVM).  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable  Java's Performance  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 24 Companion Website Characteristics of Java  Java Is Simple Java compilers can detect many problems that would first show up at execution time  Java Is Object-Oriented in other languages.  Java Is Distributed Java has eliminated certain types of error-  Java Is Interpreted prone programming constructs found in  Java Is Robust other languages.  Java Is Secure Java has a runtime exception-handling  Java Is Architecture-Neutral feature to provide programming support  Java Is Portable for robustness.  Java's Performance  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 25 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted Java implements several security  Java Is Robust mechanisms to protect your system against  Java Is Secure harm caused by stray programs.  Java Is Architecture-Neutral  Java Is Portable  Java's Performance  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 26 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral Write once, run anywhere  Java Is Portable With a Java Virtual Machine (JVM),  Java's Performance you can write one program that will run on any platform.  Java Is Multithreaded  Java Is Dynamic Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 27 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable Because Java is architecture neutral, Java programs are  Java's Performance portable. They can be run on any  Java Is Multithreaded platform without being  Java Is Dynamic recompiled. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 28 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable Java’s performance Because Java is architecture neutral, Java  Java's Performance programs are portable. They can  Java Is Multithreaded be run on any platform without  Java Is Dynamic being recompiled. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 29 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable  Java's Performance Multithread programming is smoothly  Java Is Multithreaded integrated in Java, whereas in other  Java Is Dynamic languages you have to call procedures specific to the operating system to enable multithreading. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 30 Companion Website Characteristics of Java  Java Is Simple  Java Is Object-Oriented  Java Is Distributed  Java Is Interpreted  Java Is Robust  Java Is Secure  Java Is Architecture-Neutral  Java Is Portable  Java's Performance Java was designed to adapt to an evolving environment. New code can be  Java Is Multithreaded loaded on the fly without recompilation. There is no need for developers to create,  Java Is Dynamic and for users to install, major new software versions. New features can be incorporated transparently as needed. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 31  JDK Versions  JDK 1.02 (1995) … (2022) JDK Editions  Java Standard Edition (J2SE) – J2SE can be used to develop client-side standalone applications or applets.  Java Enterprise Edition (J2EE) – J2EE can be used to develop server-side applications such as Java servlets, Java ServerPages, and Java ServerFaces.  Java Micro Edition (J2ME). – J2ME can be used to develop applications for mobile devices such as cell phones. This book uses J2SE to introduce Java programming. Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 32  Popular Java IDEs  NetBeans  Eclipse  Next Lecture Homework  Download and install JDK 8u111 with NetBeans 8.2 using this link:  https://www.oracle.com/technetwork/java/javase/downloads/jdk- netbeans-jsp-3413139-esa.html  Create your first Project  Launch the NetBeans IDE....  In the NetBeans IDE, choose File | New Project.......  In the New Project wizard, expand the Java category and select Java Application  Provide the name and location of your program nn the Name and Location page of the wizard  Click Finish.  System.out.println("Welcome to Java!"); Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 33  The Textbook Self-Test Questions https://media.pearsoncmg.com/ph/esm/ ecs_liang_ijp_12/cw/#selftest Book Website: https://media.pearsoncmg.com/ph/esm/ecs_liang_i jp_12/cw/ Liang, Introduction to Java Programming and Data Structures, Twelfth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 34