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Tuesday 20 March 2012

Read Numbers and Strings in Java

package corejava;

/**An easy interface to read numbers and strings from standard input */

public class Console
{
           /**print a prompt on the console but don|t print a newline
          @param prompt the prompt string to display */

public static void printPrompt(String prompt)
{
 System.out.print(prompt + " ");
System.out.flush();
}
       /**read a string from the console. The string is terminated by a newline
           @return the input string (without the newline)*/

public static String readLine()
int ch;
String r = "";
boolean done = false;
while (!done){ 
try { 
ch = System.in.read();
if (ch < 0 || (char)ch == |\n|)
done = true;
else if ((char)ch != |\r|)                  // weird--it used to do \r\n translation
r = r + (char) ch;
}
catch(java.io.IOException e){ 
done = true;
}}
return r;
}
           /**read a string from the console. The string is terminated by a newline
                 @param prompt the prompt string to display
                 @return the input string (without the newline) */

public static String readLine(String prompt)
printPrompt(prompt);
return readLine();
}
                   /**read an integer from the console. The input is terminated by a newline
                        @param prompt the prompt string to display
                        @return the input value as an int
                        @exception NumberFormatException if bad input */
public static int readInt(String prompt)
while(true){ 
printPrompt(prompt);
try
{
 return Integer.valueOf (readLine().trim()).intValue();
} catch(NumberFormatException e) { 
System.out.println("Not an integer. Please try again!");
}
}
}

/**read a floating point number from the console. The input is terminated by a newline
@param prompt the prompt string to display
@return the input value as a double
@exception NumberFormatException if bad input */

public static double readDouble(String prompt)
while(true) { 
printPrompt(prompt);
try
{
 return Double.parseDouble(readLine().trim());
} catch(NumberFormatException e){
 System.out.println("Not a floating point number. Please try again!");
}}}}

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