standardinputread.java

a student project for the life in Noah s ark,object oriented java

/** @author Giorgos Anestis, TUC/MUSIC
	 *  
	 *  This package was created for usage in the cs111 course
	 *  
	 * @version 1.0
	 */
	package ece.cs111.util;

	import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStreamReader;
	import java.text.DateFormat;
	import java.text.ParseException;
	import java.util.Date;
	import java.util.Locale;

	/**
	 * It reads input from the standard input hiding from the user the usage 
	 * of java.io package classes
	 */
	public class StandardInputRead {
		/** The error that is return when reading positive integers from stdin*/
		public final static int POS_ERROR = -1;
		
		/** The error that is return when reading negative integers from stdin*/
		public final static int NEG_ERROR = 1;
		
		/** The basic reader*/
		BufferedReader in;
		
		/**
		 * Class constructor
		 */
		public StandardInputRead() {
			super();
			in = new BufferedReader(new InputStreamReader(System.in));		
		}

		/**
		 * It reads a string from standard inputand returns it as value. 
		 * In case of an error it returns null
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public String readString(String message) {
			
			System.out.print(message);
			try {
				return in.readLine();
			}
			catch (IOException e) {
				return null;
			}			
		}
		
		/**
		 * It reads an positive integer, zero included, from standard input
		 * and returns it as value. In case of an error it returns -1
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public int readPositiveInt(String message) {
			
			String str;
			int num;
			
			System.out.print(message);			
			try {
				str = in.readLine();
				num = Integer.parseInt(str);
				if (num < 0 ){
					return POS_ERROR;
				}
				else {
					return num;
				}			
			}
			catch (IOException e) {			
				return POS_ERROR;
			}
			catch (NumberFormatException e1) {			
				return POS_ERROR;
			}
		}
		
		/**
		 * It reads an negative integer from standard input and returns it as value. 
		 * In case of an error it returns 1
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public int readNegativeInt(String message) {
			
			String str;
			int num;
			
			System.out.print(message);			
			try {
				str = in.readLine();
				num = Integer.parseInt(str);
				if (num >= 0 ){
					return NEG_ERROR;
				}
				else {
					return num;
				}			
			}
			catch (IOException e) {			
				return NEG_ERROR;
			}
			catch (NumberFormatException e1) {			
				return NEG_ERROR;
			}
		}

		/**
		 * It reads an positive float, zero included, from standard input
		 * and returns it as value. In case of an error it returns -1.0
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public float readPositiveFloat(String message) {
			
			String str;
			float num;
			
			System.out.print(message);			
			try {
				str = in.readLine();
				num = Float.parseFloat(str);
				if (num < 0 ){
					return POS_ERROR;
				}
				else {
					return num;
				}			
			}
			catch (IOException e) {			
				return POS_ERROR;
			}
			catch (NumberFormatException e1) {			
				return POS_ERROR;
			}
		}
		
		/**
		 * It reads an negative float from standard input and returns it as value. 
		 * In case of an error it returns 1
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public float readNegativeFloat(String message) {
			
			String str;
			float num;
			
			System.out.print(message);			
			try {
				str = in.readLine();
				num = Float.parseFloat(str);
				if (num >= 0 ){
					return NEG_ERROR;
				}
				else {
					return num;
				}			
			}
			catch (IOException e) {			
				return NEG_ERROR;
			}
			catch (NumberFormatException e1) {			
				return NEG_ERROR;
			}
		}
			
		/**
		 * It reads an date in the form dd/mm/yyyy from standard input and 
		 * returns it as value.In case of an error it returns null
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public Date readDate(String message) {
			
			String str;
			
			System.out.print(message);
			
			try {
				str = in.readLine();
				Locale l = new Locale("el", "GR");
				DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT, l);
				return df.parse(str);
			}
			catch (IOException e) {
				return null;
			}
			catch (ParseException e1) {
				return null;
			}
		}
		
		/**
		 * It reads an time in the form h:mm AM or PM from standard input and 
		 * returns it as value.In case of an error it returns null
		 * Example of valid times: 8:30 AM, 2:00 PM, etc
		 * 
		 * @param message The message that is apperad to the user asking for input
		 */
		public Date readTime(String message) {
			
			String str;
			
			System.out.print(message);
			
			try {
				str = in.readLine();		
				DateFormat df = DateFormat.getTimeInstance(DateFormat.SHORT);
				
				return df.parse(str);
			}
			catch (IOException e) {
				return null;
			}
			catch (ParseException e1) {
				return null;
			}
			
		}
			
	}