Building Java Programs.ppt

* Building Java Programs Chapter 6 Lecture 6-3: Searching Files reading: 6.3 - 6.5 Recall: Line-based methods nextLine consumes from the input cursor to the next \n . Scanner input = new Scanner(new File(filename)); while (input.hasNextLine()) { String line = input.nextLine(); process this line; } Method Description nextLine() returns the next entire line of input hasNextLine() returns true if there are any more lines of input to read (always true for console input) Recall: Tokenizing lines A String Scanner can tokenize each line of a file. Scanner input = new Scanner(new File(filename)); while (input.hasNextLine()) { String line = input.nextLine(); Scanner lineScan = new Scanner(line); process the contents of this line; } Hours v2 question Modify the Hours program to search for a person by ID: Example: Enter an ID: 456 Eric worked 36.8 hours (7.36 hours/day) Example: Enter an ID: 293 ID #293 not found Hours v2 answer 1 // This program searches an input file of employees hours worked // for a particular employee and outputs that employees hours data. import java.io.*; // for File import java.util.*; // for Scanner public class HoursWorked { public static void main(String[] args) throws FileNotFoundException { Scanner console = new Scanner(System.in); System.out.print(Enter an ID: ); int searchId = console.nextInt(); // e.g. 456 Scanner input = new Scanner(new File(hours.txt)); String line = findPerson(input, searchId); if (line.length() 0) { processLine(line); } else { System.out.println(ID # + searchId + was not found); } } ... Hours v2 answer 2 // Locates and returns the line of data about a particular person. public static String findPerson(Scanner input, int searchId) { while (input.hasNextLine()) { String line = input.nextLine(); Scanner lineScan = new Scann