console.java

Java程序设计技巧与开发实例附书源代码。

import java.io.*;
/** The <B>Console</B> class provides methods that allow easy reading of the basic
    data types <TT>double</TT>, <TT>int</TT>, and <TT>String</TT> from standard input.
    <I>Must be placed in the same directory as the source code using it.</I><P>

     <B>Usage Example:</B>
     <PRE>
     System.out.println("Enter a double number: ");
     double x = Console.readDouble();
     System.out.println("You have entered: " + x);
      </PRE>
 */
public class Console
{/** Reads a single double from the keyboard. Stops execution in case of
error.
      @return double   */
   public static double readDouble()
   {  try
      {  return Double.valueOf(readString().trim()).doubleValue(); }
      catch(NumberFormatException ne)
      {  System.err.println("Console.readDouble: Not a double...");
         System.exit(-1);
         return 0.0;
      }
   }
   /** Reads a single int from the keyboard. Stops execution in case of error.
       @return int   */
   public static int readInt()
   {  try
      {  return Integer.valueOf(readString().trim()).intValue(); }
      catch(NumberFormatException ne)
      {  System.err.println("Console.readInt: Not an integer...");
         System.exit(-1);
         return -1;
      }
   }
   /** Reads a String from the keyboard until RETURN or ENTER key is pressed.
       @return String  */
   public static String readString()
   { String string = new String();
     BufferedReader in=
new BufferedReader(new InputStreamReader(System.in));
      try
      {  string = in.readLine(); }
      catch(IOException e)
      { System.out.println("Console.readString: Unknown error...");
        System.exit(-1);
      }
      return string;
   }
}