import java.io.*;

/**
 * The <code>Input</code> is a class for reading user input
 * from the command line. It includes methods for reading a single <code>char</code>, 
 * <code>int</code>, and <code>float</code>. In addition to reading primitive data
 * types, the class can read a line of input as a <code>String</code>.
 *
 * @author Petri Mikael Gerdt
 * @version 1.0 (May 12, 2003)
 */
public class Input {

    public static String readInputLine() {
	BufferedReader input;
	String buffer;
	input = new BufferedReader(new InputStreamReader(System.in));
	try {
	    buffer = input.readLine();
	} catch (IOException ioe) {
	    System.out.println("Error: can't read input");
	    buffer = null;
	}
	return buffer;
    }
  
    public static double readDouble() {
	String s = readInputLine();
	Double retval = null;
	if (s != null) {
	    while (retval == null) {
		try {
		    retval = Double.valueOf(s);
		} catch (NumberFormatException nfe) {
		    System.out.println("Error: can't parse a double from string " + s);
		    System.out.print("Enter a new value (example: 3.14): ");
		    s = readInputLine();
		}
	    }
	}
	return retval.doubleValue();
    }

    public static float readFloat() {
	String s = readInputLine();
	Float retval = null;
	if (s != null) {
	    while (retval == null) {
		try {
		    retval = Float.valueOf(s);
		} catch (NumberFormatException nfe) {
		    System.out.println("Error: can't parse a float from string " + s);
		    System.out.print("Enter a new value (example: 3.14): ");
		    s = readInputLine();
		}
	    }
	}
	return retval.floatValue();
    }

    public static int readInt() {
	String s = readInputLine();
	Integer retval = null;
	if (s != null) {
	    while (retval == null) {
		try {
		    retval = Integer.valueOf(s);
		} catch (NumberFormatException nfe) {
		    System.out.println("Error: can't parse a int from string " + s);
		    System.out.print("Enter a new value (example: 3): ");
		    s = readInputLine();
		}
	    }
	}
	return retval.intValue();
    }

    public static char readChar() {
	String s = readInputLine();
	Character retval = null;
	if (s != null) {
	    while (retval == null) {
		if (s.length() == 1) retval = new Character(s.charAt(0)); 
		else {
		    System.out.println("Error: input is a string, not a character: " + s);
		    System.out.print("Enter a new value (example: a): ");
		    s = readInputLine();
		}
	    }
	}
	return retval.charValue();
    }

}