![Solution: Arrays of Days
public class DayPrinter {
public static void main(String[] args) {
//initialize the array with the names of days of the
week
String[] daysOfTheWeek =
{"Sunday","Monday","Tuesday","Wednesday",
"Thuesday","Friday”,"Saturday"};
//loop through the array and print their elements to
//stdout
for (int i= 0;i < daysOfTheWeek.length;i++ ){
System.out.println(daysOfTheWeek[i]);
}
}
}
% javac DayPrinter.java
% java DayPrinter
Sunday
Monday
Tuesday
Wednesday
Thuesday
Friday
Saturday](https://image.slidesharecdn.com/java101-introtoprogrammingwithjava-160406232034/85/Java-101-intro-to-programming-with-java-73-320.jpg)
Java 101 intro to programming with java
- 1. Java 101: Intro to Java Programming
- 2. Introduction • Your Name • Your day job • Your last holiday destination?
- 3. Java 101 • Java Fundamentals – Setting up your development environment – Language Overview – How Java Works – Writing your first program – Built-in Data Types – Conditionals and Loops
- 4. Java 102 • Object-oriented Programming – Classes and Objects – Polymorphism, Inheritance and Encapsulation – Functions and Libraries
- 5. Java 103 • Data Structures – Arrays – Collections – Algorithms
- 6. Java 101: Introduction to Java Setting up your Development Environment
- 7. Installing Java Development Kit • Download latest Java SE 8 JDK (not JRE) from http://www.oracle.com/technetwork/java/javase/downloads/jdk8- downloads-2133151.html • For Windows, – download the X86 version, double click the .exe file and follow the instructions, accepting all default • For MACs, – check if java already installed (javac –version) and if not, download the JDK dmg file, run it and follow the instructions. • After installation is complete, type javac –version in the Command window (Terminal window on MAC OS)- – The reported version should be 1.8.... – If not, you may need to modify the system variable PATH to include the bin directory of JDK
- 8. What is an IDE? • IDE = Integrated Development Environment • Makes you more productive • Includes text editor, compiler, debugger, context- sensitive help, works with different Java SDKs • Eclipse is the most widely used IDE • Alternatives: – IntelliJ IDEA (JetBrains) – NetBeans (Oracle)
- 9. Installing Eclipse • Download and install the latest Eclipse for Java EE (32 Bit version) from http://www.eclipse.org/downloads • Unzip the content of the archive file you downloaded • To start Eclipse – On PC, double-click on Eclipse.exe – On Mac, double click Eclipse.app in Application folder
- 10. Hands-on Exercise Eclipse Setup & Demo
- 11. Java 101: Introduction to Java Language Overview
- 12. Java Language Overview • Object-oriented • Statically typed • Widely available • Widely used
- 13. Java Versions • Brief History… – 1990 : Small team at Sun Microsystems start work on C/C++ replacement • Major Version Releases – JDK 1.0 (January 21, 1996) – JDK 1.1 (February 19, 1997) – J2SE 1.2 (December 8, 1998) – J2SE 1.3 (May 8, 2000) – J2SE 1.4 (February 6, 2002) – J2SE 5.0 (September 30, 2004) – Java SE 6 (December 11, 2006) – Java SE 7 (July 28, 2011) – Java SE 8 (March 18, 2014)
- 14. Java Editions • Java SE: Java Standard Edition • Java EE: Java Enterprise Edition (a.k.a. J2EE) – includes a set of technologies built on top of Java SE: Servlets, JSP, JSF, EJB, JMS, et al. • Java ME: Java Micro Edition • Java Card for Smart Cards • All Java programs run inside the Java Virtual Machine (JVM)
- 15. JDK vs. JRE • Java Development Kit (JDK) is required to develop and compile programs • Java Runtime Environment (JRE) is required to run programs. • Users must have JRE installed, • Developers must have the JDK installed • JDK includes the JRE
- 16. Java 101: Introduction to Java How Java Works
- 17. How Java Works
- 19. Java 101: Introduction to Java Writing Your First Program
- 20. Hello, World!
- 21. Writing Your First Java Program • Create a new project in your IDE named Java101 • Create a HelloWorld class in the src folder inside the Java101 project as illustrated below.
- 22. Compiling Your First Java Program • Save the HelloWorld class in the IDE • This automatically compiles the HelloWorld.java file into into a HelloWorld.class file • Go to the folder you created the Java101 project on your hard disk and open the src folder. • What do you see?
- 23. Running Your First Java Program • Run your program in Eclipse by right-clicking and selecting Run As>Java Application.
- 25. Anatomy of a Java Application Comments Class Name Access modifier Function/static method Arguments
- 27. Introduction to Java Built-in Data Types
- 28. Built-in Data Types • Data type are sets of values and operations defined on those values.
- 29. Basic Definitions • Variable - a name that refers to a value. • Assignment statement - associates a value with a variable.
- 30. String Data Type Data Type Attributes Values sequence of characters Typical literals “Hello”, “1 “, “*” Operation Concatenate Operator + • Useful for program input and output.
- 31. String Data Type
- 32. String Data Type • Meaning of characters depends on context.
- 33. String Data Type Expression Value “Hi, “ + “Bob” “Hi, Bob” “1” + “ 2 “ + “ 1” “ 1 2 1” “1234” + “ + “ + “99” “1234 + 99” “1234” + “99” “123499”
- 34. Hands-on Exercise Command Line Arguments
- 35. Exercise: Command Line Arguments • Create the Java program below that takes a name as command-line argument and prints “Hi <name>, How are you?”
- 36. Integer Data Type Data Type Attributes Values Integers between -2E31 to +2E31-1 Typical literals 1234, -99 , 99, 0, 1000000 Operation Add subtract multiply divide remainder Operator + - * / % • Useful for expressing algorithms.
- 37. Integer Data Type Expression Value Comment 5 + 3 8 5 – 3 2 5 * 3 15 5 / 3 1 no fractional part 5 % 3 2 remainder 1 / 0 run-time error 3 * 5 - 2 13 * has precedence 3 + 5 / 2 5 / has precedence 3 – 5 - 2 -4 left associative (3-5) - 2 -4 better style 3 – (5-2) 0 unambiguous
- 38. Double Data Type • Useful in scientific applications and floating- point arithmetic Data Type Attributes Values Real numbers specified by the IEEE 754 standard Typical literals 3.14159 6.022e23 -3.0 2.0 1.41421356237209 Operation Add subtract multiply divide Operator + - * /
- 39. Double Data Type Expression Value 3.141 + 0.03 3.171 3.141 – 0.03 3.111 6.02e23 / 2 3.01e23 5.0 / 2.0 1.6666666666667 10.0 % 3.141 0.577 1.0 / 0.0 Infinity Math.sqrt(2.0) 1.4142135623730951
- 40. Java Math Library Methods Math.sin() Math.cos() Math.log() Math.exp() Math.sqrt() Math.pow() Math.min() Math.max() Math.abs() Math.PI http://java.sun.com/javase/6/docs/api/java/lang/Math.html
- 42. Exercise: Integer Operations • Create a Java class named IntOpsin the Java101 project that performs integer operations on a pair of integers from the command line and prints the results.
- 44. Boolean Data Type • Useful to control logic and flow of a program. Data Type Attributes Values true or false Typical literals true false Operation and or not Operator && || !
- 45. Truth-table of Boolean Operations a !a a b a && b a || b true false false false false false false true false true false true true false false true true true true true
- 46. Boolean Comparisons • Take operands of one type and produce an operand of type boolean. operation meaning true false == equals 2 == 2 2 == 3 != Not equals 3 != 2 2 != 2 < Less than 2 < 13 2 < 2 <= Less than or equal 2 <= 2 3 <= 2 > Greater than 13 > 2 2 > 13 >= Greater than or equal 3 >= 2 2 >= 3
- 47. Type Conversion • Convert from one type of data to another. • Implicit – no loss of precision – with strings • Explicit: – cast – method.
- 48. Type Conversion Examples expression Expression type Expression value “1234” + 99 String “123499” Integer.parseInt(“123”) int 123 (int) 2.71828 int 2 Math.round(2.71828) long 3 (int) Math.round(2.71828) int 3 (int) Math.round(3.14159) int 3 11 * 0.3 double 3.3 (int) 11 * 0.3 double 3.3 11 * (int) 0.3 int 0 (int) (11 * 0.3) int 3
- 49. Hands-on Exercise Leap Year Finder
- 50. Exercise: Leap Year Finder • A year is a leap year if it is either divisible by 400 or divisible by 4 but not 100. • Write a java class named LeapYear in the Java101 project that takes a numeric year as command line argument and prints true if it’s a leap year and false if not
- 51. Solution: Leap Year Finder
- 52. Data Types Summary • A data type is a set of values and operations on those values. – String for text processing – double, int for mathematical calculation – boolean for decision making • In Java, you must: – Declare type of values. – Convert between types when necessary • Why do we need types? – Type conversion must be done at some level. – Compiler can help do it correctly. – Example: in 1996, Ariane 5 rocket exploded after takeoff because of bad type conversion.
- 53. Introduction to Java Conditionals and Loops
- 54. Conditionals and Loops • Sequence of statements that are actually executed in a program. • Enable us to choreograph control flow.
- 55. Conditionals • The if statement is a common branching structure. – Evaluate a boolean expression. • If true, execute some statements. • If false, execute other statements.
- 57. More If Statement Examples
- 58. While Loop • A common repetition structure. – Evaluate a boolean expression. – If true, execute some statements. – Repeat.
- 59. For Loop • Another common repetition structure. – Execute initialization statement. – Evaluate a boolean expression. • If true, execute some statements. – And then the increment statement. – Repeat.
- 60. Anatomy of a For Loop
- 61. Loop Examples
- 62. For Loop
- 63. Hands-on Exercise Powers of Two
- 64. Exercise: Powers of Two • Create a new Java project in Eclipse named Pow2 • Write a java class named PowerOfTwo to print powers of 2 that are <= 2N where N is a number passed as an argument to the program. – Increment i from 0 to N. – Double v each time
- 65. Solution: Power of 2
- 66. Control Flow Summary • Sequence of statements that are actually executed in a program. • Conditionals and loops enable us to choreograph the control flow. Control flow Description Example Straight line programs all statements are executed in the order given Conditionals certain statements are executed depending on the values of certain variables If If-else Loops certain statements are executed repeatedly until certain conditions are met while for do-while
- 67. Homework Exercises Java 101: Introduction to Java
- 68. Hands-on Exercise Random Number Generator
- 69. Exercise: Random Number Generator • Write a java class named RandomInt to generate a pseudo-random number between 0 and N-1 where N is a number passed as an argument to the program
- 70. Solution: Random Number Generator
- 71. Hands-on Exercise Array of Days
- 72. Exercise: Array of Days • Create a java class named DayPrinter that prints out names of the days in a week from an array using a for-loop.
- 73. Solution: Arrays of Days public class DayPrinter { public static void main(String[] args) { //initialize the array with the names of days of the week String[] daysOfTheWeek = {"Sunday","Monday","Tuesday","Wednesday", "Thuesday","Friday”,"Saturday"}; //loop through the array and print their elements to //stdout for (int i= 0;i < daysOfTheWeek.length;i++ ){ System.out.println(daysOfTheWeek[i]); } } } % javac DayPrinter.java % java DayPrinter Sunday Monday Tuesday Wednesday Thuesday Friday Saturday
- 74. Hands-on Exercise Print Personal Details
- 75. Exercise: Print Personal Details • Write a program that will print your name and address to the console, for example: Alex Johnson 23 Main Street New York, NY 10001 USA
- 77. Exercise: Sales Discount • Create a new project in Eclipse named Sale • Create, compile, and run the FriendsAndFamily class as illustrated below • Debug this program in your IDE to find out how it works
- 78. Further Reading • Java Tutorials - https://docs.oracle.com/javase/tutorial/ • Java Language Basics - http://docs.oracle.com/javase/tutorial/java/nutsandbolts/index.html • Eclipse IDE Workbench User Guide - http://help.eclipse.org/kepler/index.jsp • Eclipse Tutorial - http://www.vogella.com/tutorials/Eclipse/article.html
Editor's Notes
- #21: Source: http://profitswithjody.com/wp-content/uploads/2012/11/hello_world_Wallpaper_5ze28.jpg