Lecture 19: Reading Input from Files Announcements & Review Lab 6 Due Thursday arrays of objects more flight reservations Last time: static methods vs object methods Today: review static vs object methods Reading from files

Lecture 19: Reading Input from Files Class, Variables, Methods Class - a model for an object instance –one class, lots of objects Class variable declarations – type variableName; private - only accessible through method calls, e.g., get and set methods public - accessible directly, e.g., objectName.varName static - one per class non-static - one per object Class method declarations – methodName; private - only accessible within the class public - accessible from clients static - invoke on the class non-static - invoke on an object of the class

Lecture 19: Reading Input from Files Java Examples in BlueJ Adding static methods for input Putting static methods together with arrays

Lecture 19: Reading Input from Files So far, user input from the console stdin.next(); // a string stdin.nextLine(); // a line of text stdin.nextInt(); // an integer, etc. stdin.hasNextInt(); // First make sure there is one... Scanner stdin = new Scanner (System.in); System.out.println(“Input an integer:”) while (!stdin.hasNextInt()) { System.out.println(“Input an integer:”) stdin.nextLine(); // consumes bad input } int i = stdin.nextInt();

Lecture 19: Reading Input from Files Lots of Input? and/or Persistant Input Store and read input from a file

Lecture 19: Reading Input from Files File Input Syntax Scanner stdin = new Scanner(System.in); System.out.println("Input a file name: "); String fileName = stdin.next(); Scanner groceryFile = new Scanner(new File(fileName)); while (!groceryFile.hasNextInt()) { System.out.println("File did not start with an integer."); groceryFile.nextLine(); // consumes bad input } int totalEntries = groceryFile.nextInt(); Read the file by making it into Scanner object, and then treat it like stdin, where stdin = new Scanner (System.in)

Lecture 19: Reading Input from Files Java Examples in BlueJ Reading from a file Array of objects initialized from a file

Lecture 19: Reading Input from Files More Questions?