school/java/old/week8/exception-output-file/mainProgram.java

import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
/*
 * Same as the input one and the string vs int one, but now writting to a file
 * instead of the screen.
*/

public class mainProgram {

	public static  ArrayList<String> readInput(final String fileName)
			throws IOException{

		FileInputStream fileByteStream = null; // File input stream
		Scanner scnr = null;  				   // Scanner object

		System.out.println("Opening file " + fileName);
		fileByteStream = new FileInputStream(fileName);
		scnr = new Scanner(fileByteStream);

		String s = "";
		String name;
		int age;

		ArrayList<String> results = new ArrayList<String>();

		while(true){

			//Get name or exit
			s = scnr.next();

			if (s.equals("-1")){
				System.out.println();
				break;
			}
			else{
				name = s;
			}

			//Get age

			try{
				age = scnr.nextInt() +1;
			}
			catch(Exception e){
				System.out.println("Age must be an Integer\n" +
						           "Setting age to 0 ");
				age = 0;

			}
			//Finish line
			scnr.nextLine();

			//Add name plus new age to arr
			results.add(name + " " + Integer.toString(age));

			System.out.println();
		}
		System.out.println("Closing scanner:");
		fileByteStream.close();
		scnr.close();
		return results;
	}

	public static void writeArrayListToFile(ArrayList<String> arr,
											final String fileName)
			throws IOException{
		FileOutputStream fileStream = null;
		PrintWriter file = null;

		fileStream = new FileOutputStream(fileName);
		file = new PrintWriter(fileStream);

		System.out.println("Writing out results " +
				           "To " + fileName );
		for (String S:arr){
			file.println(S);
		}
		file.flush();
		fileStream.close();
		file.close();
	}

	public static void main(String[] args) throws IOException{

	 final String  INPUTFILENAME = "NamesAndAges.txt";
	 final String  OUTPUTFILENAME = "NamesAndAgesUpdated.txt";

		ArrayList<String> userInputs;

		//Get input
		userInputs = readInput(INPUTFILENAME);

		//Write to file
		writeArrayListToFile(userInputs, OUTPUTFILENAME);
	}
}