import java.util.*;		// for Scanner class and a few other useful things
import java.io.*;		// to enable reading and writing from files

public class FileIOExample {
	
	/* you need to include the "throws IOException" declaration
	 * because things may go wrong with the file I/O process
	 * 
	 * unless you want to use try-catch statements
	 */
	public static void main(String[] args) throws IOException {

		// this line opens a Scanner to read from your input file
		// it reads just as if you were typing things into the console
		Scanner input = new Scanner(new File("input.txt"));
		
		// this next line creates a file and allows you to print to it
		// you use it like System.out.println()
		PrintWriter out = new PrintWriter(new File("output.txt"));
		
		// for instance, if you want to read in a list of integers from a file...
		List<Integer> list = new ArrayList<Integer>();
		while (input.hasNextInt()) {
			list.add(input.nextInt());
		}
		
		// then, if you want to sort the numbers and print it back out to your file...
		Collections.sort(list);
		for (Integer i : list) {
			out.println(i);		// just like printing to console...! without the System	
		}
		
		/* THESE NEXT TWO LINES ARE IMPORTANT... since you opened two files, one for reading and
		 * one for writing, you have to close those files so that it releases the resources
		 * back to your computer
		 */
		input.close();
		out.close();
	}

}