Java Lecture 1.pdf页面提取自－ Java 2.pdfIntroduction to Java EE 518: Mathematics and Tools for Financial EngineeringGoal • Understand the activity of programming • Design, compile and run Java program • Become familiar with OOP • Software debugging and testingTopics • Introduction, tool setup • Data types, operators, conditionals, and loops • Classes, objects, and methods • Arrays and Array Lists • Inheritance and Polymorphism • Applications in FinanceReferences • Software: – JRE: Java Runtime Environment – JDK: Java Development Kit – Eclipse: Integrated Development Environment • Books: – Big Java, by Cay S. Horstmann – Thinking in Java, by Bruce Eckel – The Java Tutorials, by OracleIntroduction to Java Java BeginningWhat is Programming? • A computer must be programmed to perform tasks • A computer program executes a sequence of basic operations – W = x + y +z Read location x Read location y Read location z Add x, y and z Write to location wWhat is Programming? • X dw 5 • Y dw 6 • Z dw 7 • W dw ? • mov ax,X • add ax,Y • add ax,Z • mov W,axProgramming Languages • Easier to understand than machine codes – C, C++, C#, Visual C++, BASIC… – Java, JavaScript, JRuby… – MATLAB, FORTRAN, R, … – PHP, Perl, Python, Shell, ASP, JSP, … – HTML, XML, XHTML, … • Ten most popular programming languages are (in descending order by overall popularity): C, Java, PHP, JavaScript, C++, Python, Shell, Ruby, Objective-C and C#.Java Programming Language • “Most popular” language • Class based and object based • Runs on a virtual machine (JVM) • Simpler than C++ • Successfully used to write Internet applets • Has a very large libraryJava Programming Process • Needs to be translated for the computer to understand itExample Program • Classes are the fundamental building blocks of Java programs • Every Java application contains a class with a main methodRun Java ProgramRun Java ProgramRun Java ProgramAny Questions?Introduction to Java Types, Variables, and OperatorsTypes • Every value in Java has a type • boolean: Truth value (true or false) • int: Integer (0, -1, 1) • double: Real number (-1.1, 3.14) • String: Text • Create a Variable • Type VarName = ValueTypes • int a = 3; // a = 3 • double a = 3; // a = 3.0 • int b = 1.7; // ERROR • int b = (int)1.7; // b = 1 • double c = 2/3; // c = ? • double c = (double)2/3; // c = ?Operators • Assignment: = • Addition: + • Subtraction: - • Multiplication: * • Division: /VariablesChecking Problem • What do the following statements print: – System.out.println(“3 + 4”); – System.out.println(3 + 4); – System.out.println(3 + “4”);Checking Problem • What do the following statements print: – System.out.println(“3 + 4”); //String – 3 + 4 – System.out.println(3 + 4); //Integer – 7 – System.out.println(3 + “4”);//Integer + String – 34Any Questions?Introduction to Java Conditionals and LoopsAny Questions?Introduction to Java OOP Introduction Classes, Objects, MethodsOOP • Object Oriented Programming • Objects are entities that manipulate by calling methods • Method is a sequence of instructions that accesses the data of an object • Class defines the data and methods that you can apply to its objectsOOP - Class • Example: represent a USC student in program – Name – Sex – USC ID – USC username – Department – Degree – ……OOP - Class • Example: represent a USC student in program – String name – boolean sex – int uscid – String username – String department – String degree – ……OOP - Class • Why use classes? • Why not define directly – String name1 – boolean sex1 – int uscid1 – String username1 – String department1 – String degree1OOP - Class • Define a student classOOP – Creating ObjectsOOP – Creating ObjectsOOP – Creating Objects • Constructor name = Class name • No return values • Initialize the fieldsOOP – Creating ObjectsOOP - Methods • Constructor and main are methodsOOP - Methods • Adding MethodsOOP – Adding Methods • Multiple Arguments • […] MethodName (Type1 Name1, Type2 Name2, …){ Statements } • To Call: • MethodName(argument1, argument2)Any