telnumber.java

程序练习中包括书中实例程序代码和练习中要用到的代码,是压缩文件

package examples.classes;

/** A class definition to show how a method name 
  * can be overloaded 
  */
public class TelNumber { 
   /** Print a telephone number
     * @param s the telephone number as a string
     */
   public static void printTelNumber( String s ) {
      // check for digits only
      for ( int i = 0; i < s.length(); i++ ) {
         if ( ! Character.isDigit( s.charAt( i ) ) ) {
            System.out.println( "Not valid: " + s );
            return;
         }
      }
      // format string into (ddd) ddd-dddd
      StringBuffer sb = new StringBuffer( s );
      while ( sb.length() < 10 ) {
         sb.insert( 0, '0');
      }
      sb.insert( 6, '-' );
      sb.insert( 3, ") " );
      sb.insert( 0, '(' ); 
      System.out.println( sb );
   }

   /** Print a telephone number if it falls within
     * the valid range.  This method will convert
     * the long to a string and then call the
     * PrintTelNumber method that takes String
     * input
     * @param l the telephone number as a long
     */
   public static void printTelNumber( long l ) {
      if ( l >= 0 && l < 10000000000L ) {
         // convert the number to a string
         printTelNumber( Long.toString( l ) ); 
      } else {
         System.out.println( "Not valid: " + l );
      }
   } 

   /** Test method for the class
     * @param args not used
     */
   public static void main( String[] args ) {
      printTelNumber( "abcdefghij" );
      printTelNumber( "4166448300" );
      printTelNumber( 1234567890 );
      printTelNumber( -5 );
      printTelNumber( 5439432 );
      printTelNumber( "" );    
   }
}