FileHandlingEx.java

import java.io.*;

// A character stream is just a series of characters
// Important information is normally separated by a comma,
// space, or tab.

public class {
	
	public static void main(String[] args){
		
		// Create an array of type Customer
		
		Customer[] customers = getCustomers();
		
		// PrintWriter is used to write characters to a file in this situation
		
		PrintWriter custOutput = createFile("/Users/derekbanas/Documents/workspace3/Java Code/src/customers.txt");
		
		// Enhanced for loop for arrays
		// Cycles through all of the people in the customers array
		
		for(Customer person : customers){
			
			createCustomers(person, custOutput);
			
		}
		
		// Closes the connection to the PrintWriter
		
		custOutput.close();
		
		getFileInfo();
		
	}
	
	// class that defines all the fields for my customers
	
	private static class Customer{
		
		public String firstName, lastName;
		public int custAge;
		
		// constructor that's called when a customer is made
		
		public Customer(String firstName, String lastName, int custAge){
			
			this.firstName = firstName;
			this.lastName = lastName;
			this.custAge = custAge;
			
		}
		
	}
	
	// Creates an array of Customer Objects
	
	private static Customer[] getCustomers(){
		
		Customer[] customers = new Customer[5];
		
		customers[0] = new Customer("John", "Smith", 21);
		customers[1] = new Customer("Sally", "Smith", 30);
		customers[2] = new Customer("Paul", "Ryan", 21);
		customers[3] = new Customer("Mark", "Jacobs", 21);
		customers[4] = new Customer("Steve", "Nash", 21);
		
		return customers;
		
	}
	
	// Create the file and the PrintWriter that will write to the file
	
	private static PrintWriter createFile(String fileName){
		
		try{
			
			// Creates a File object that allows you to work with files on the hardrive
			
			File listOfNames = new File(fileName);
			
			// FileWriter is used to write streams of characters to a file
			// BufferedWriter gathers a bunch of characters and then writes
			// them all at one time (Speeds up the Program)
			// PrintWriter is used to write characters to the console, file
	
			PrintWriter infoToWrite = new PrintWriter(
			new BufferedWriter(
					new FileWriter(listOfNames)));
			return infoToWrite;
		}
	
		// You have to catch this when you call FileWriter
		
		catch(IOException e){
		
			System.out.println("An I/O Error Occurred");
			
			// Closes the program
			
			System.exit(0);
		
		}
		return null;
		
	}
	
	// Create a string with the customer info and write it to the file
	
	private static void createCustomers(Customer customer, PrintWriter custOutput){
		
		// Create the String that contains the customer info
		
		String custInfo = customer.firstName + " " + customer.lastName + " ";
		custInfo += Integer.toString(customer.custAge);
		
		// Writes the string to the file
		
		custOutput.println(custInfo);
		
	}
	
	// Read info from the file and write it to the screen
	
	private static void getFileInfo(){
		
		System.out.println("Info Written to File\n");
		
		// Open a new connection to the file
		
		File listOfNames = new File("/Users/derekbanas/Documents/workspace3/Java Code/src/customers.txt");
		
		try {
			
			// FileReader reads character files
			// BufferedReader reads as many characters as possible
			
			BufferedReader getInfo = new BufferedReader(
					new FileReader(listOfNames));
			
			// Reads a whole line from the file and saves it in a String
			
			String custInfo = getInfo.readLine();
			
			// readLine returns null when the end of the file is reached
			
			while(custInfo != null){
				
				// System.out.println(custInfo);
				
				// Break lines into pieces
				
				String[] indivCustData = custInfo.split(" ");
				
				// Convert the String into an integer with parseInt
				
				int custAge = Integer.parseInt(indivCustData[2]);
				
				System.out.print("Customer " + indivCustData[0] + " is " + custAge +"\n");
				
				custInfo = getInfo.readLine();
				
			}
			
			
			
		} 
		
		// Can be thrown by FileReader
		
		catch (FileNotFoundException e) {
			
			System.out.println("Couldn't Find the File");
			System.exit(0);
		}
		
		catch(IOException e){
			
			System.out.println("An I/O Error Occurred");
			System.exit(0);
		
		}
		
	}
	
	
}