Advanced Search

Generics - List of unknown - adding type restrictions.

/ Published in: Java
Save to your folder(s)
Za typ N można podstawić dowolny typ dziedziczący po Number.

Expand | Embed | Plain Text

Copy this code and paste it in your HTML 
  1. public class NumberBox<N extends Number> extends Box<N> {
  2.  
  3.  
  4.  
  5.   public NumberBox( ) {
  6.  
  7.     super( );
  8.  
  9.   }
  10.  
  11.  
  12.  
  13.   // Sum everything in the box
  14.  
  15.   public double sum( ) {
  16.  
  17.     double total = 0;
  18.  
  19.     for (Iterator<N> i = contents.iterator( ); i.hasNext( ); ) {
  20.  
  21.       total = total + i.next( ).doubleValue( );
  22.  
  23.     }
  24.  
  25.     return total;
  26.  
  27.   }
  28.  
  29. }
  30.  
  31. You can use this same syntax in method definitions:
  32.  
  33.     public static double sum(Box<? extends Number> box1,
  34.  
  35.                              Box<? extends Number> box2) {
  36.  
  37.       double total = 0;
  38.  
  39.       for (Iterator<? extends Number> i = box1.contents.iterator( );
  40.  
  41.            i.hasNext( ); ) {
  42.  
  43.         total = total + i.next( ).doubleValue( );
  44.  
  45.       }
  46.  
  47.       for (Iterator<? extends Number> i = box2.contents.iterator( );
  48.  
  49.            i.hasNext( ); ) {
  50.  
  51.         total = total + i.next( ).doubleValue( );
  52.  
  53.       }
  54.  
  55.       return total;
  56.  
  57.     }

Report this snippet


Comments

RSS Icon Subscribe to comments

You need to login to post a comment.