Java Programming Pancakes In one bowl mix: sequence of 1 cup - PowerPoint PPT Presentation

Hello Hello World World What is a program? ■ Definition: a Java Programming Pancakes In one bowl mix: sequence of 1½ cup flour instructions telling TOPICS CS 160, Fall Semester 2012 CS 160, Fall Semester 2012 1 tbsp sugar a computer what • Computer Programs to do 1 tsp salt • Using Eclipse 1 tsp baking • Hello World Program • Program Components ■ Analogy: cooking powder recipes CS 160, Summer Semester 2016 1 CS 160, Summer Semester 2016 2 Hello Hello World World Programs ≠ Recipes Programs as Recipes At some point the analogy breaks down: Recipes specify ■ ■ Recipes are read by people What ingredients to use 1. ■ People can make inferences. What to do with them 2. ■ If something goes wrong, people react. Sometimes conditional: “bake until golden brown”, “salt ■ ■ People sometimes make mistakes. to taste” Programs specify ■ ■ Programs are read by machines What information (data) to use 1. ■ Machines do exactly what they are told! What operations to apply 2. ■ No matter how badly things go wrong. Sometimes conditional: “while file is not empty”, “for ■ ■ But, they never make mistakes or get tired. every element in array” CS 160, Summer Semester 2016 3 CS 160, Summer Semester 2016 4

Hello Hello World World Definitions Object-oriented programming ■ program ■ Java programs use objects and methods ■ a set of directions telling a computer exactly what to do ■ An ‘object’ is a collection of code and data that you ■ programming languages treat as a unit. ■ precise languages for specifying sequences of ■ Objects have ‘methods’ – code that implements directions to a computer actions that apply to the object. ■ unlike English -- no ambiguities! no nuances! ■ Objects have ‘members’ – data that is associated ■ algorithm with the object. ■ a sequence of steps to be followed to solve a ■ A Java cooking program might have a line like problem ■ independent of any programming language ‘egg.scramble()’ to scramble an egg… CS 160, Summer Semester 2016 5 CS 160, Summer Semester 2016 6 Hello Hello World World ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ … ■ CS 160, Summer Semester 2016 7 CS 160, Summer Semester 2016 8

Hello Hello Hello World Program World World // HelloWorld // Author: Gareth Halladay // Date: 6/13/2016 // Class: CS160 // Email: gareth@rams.colostate.edu import java.lang.*; public class HelloWorld { public static void main(String[] args) { System. out .println( "Hello World!" ); } } CS 160, Summer Semester 2016 9 CS 160, Summer Semester 2016 10 Hello Hello Import directive World World ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ CS 160, Summer Semester 2016 11 CS 160, Summer Semester 2016 12

Hello Hello World World ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ CS 160, Summer Semester 2016 13 CS 160, Summer Semester 2016 14 Hello Hello World World ▪ ▪ ▪ ▪ ▪ ▪ ▪ CS 160, Summer Semester 2016 15 CS 160, Summer Semester 2016 16

Hello Hello World World ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ CS 160, Summer Semester 2016 17 CS 160, Spring Semester 2016 18 Hello World ▪ CS 160, Summer Semester 2016 19