Read Files with the Scanner Object in Java

Reading Files with Scanner

Include these lines at top of program: import java.util.Scanner; import java.io.*;

Create a Scanner object to read your file:
Scanner inFile = null; try { // Create a scanner to read the file, file name is parameter inFile = new Scanner (new File("whatever.txt")); } catch (FileNotFoundException e) { System.out.println ("File not found!"); // Stop program if no file found System.exit (0); }

Methods you can use:

inFile.hasNext( ) – returns true if there is more data in the file. inFile.nextInt( ) – gets the next value in the file. This must be an integer or you will get an Input Mismatch Exception . Return data type is int. inFile.nextDouble( ) – gets the next value in the file. This must be a number or you will get an Input Mismatch Exception . Return data type is double. inFile.nextLine( ) – gets the next ENTIRE line in the file. Return data type is String. inFile.next( ) – gets the next value in the file. Return data type is String. Essentially reads the file word by word. inFile.close( ) - closes the file

There are other methods, but these will get us started!

Example programs and files follow.
EXAMPLE PROGRAMS:
// read all ints in a file import java.util.Scanner; import java.io.*; public class ReadInts
{
public static void main(String args[]) { System.out.println("***** Reading Integers from a file ****"); System.out.println(); Scanner inFile = null; try { // Create a scanner to read the file, file name is parameter inFile = new Scanner (new File("nums.txt")); } catch (FileNotFoundException e) { System.out.println ("File not found!"); // Stop program if no file found System.exit (0); }

//****************************************************** // Read the file while data still found // Print out the