Demonstrates the use of final collections

   
/*
 *     file: FinalCollections.java
 *  package: oreilly.hcj.finalstory
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
 ########## DO NOT EDIT ABOVE THIS LINE ########## */

import java.awt.Color;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Demonstrates the use of final collections.
 * 
 * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
 * @version $Revision: 1.3 $
 */
public class FinalCollections {
  /**
   * Main method for demonstration.
   * 
   * @param args
   *          Command line arguments.
   */
  public static final void main(final String[] args) {
    Rainbow.someMethod();
    System.out.println("------------------");
    try {
      RainbowBetter.someMethod();
    } catch (final UnsupportedOperationException ex) {
      ex.printStackTrace(System.out);
      System.out.println("Told you it would exception =)");
    }
  }

  /**
   * A class that demonstrates the rainbow.
   * 
   * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
   * @version $Revision: 1.3 $
   */
  public static class Rainbow {
    /** The set of valid colors of the rainbow. */
    public static final Set VALID_COLORS;

    static {
      VALID_COLORS = new HashSet();
      VALID_COLORS.add(Color.red);
      VALID_COLORS.add(Color.orange);
      VALID_COLORS.add(Color.yellow);
      VALID_COLORS.add(Color.green);
      VALID_COLORS.add(Color.blue);
      VALID_COLORS.add(Color.decode("#4B0082")); // indigo
      VALID_COLORS.add(Color.decode("#8A2BE2")); // violet
    }

    /**
     * A demo method.
     */
    public static final void someMethod() {
      Set colors = Rainbow.VALID_COLORS;
      colors.add(Color.black); // <= logic error but allowed by compiler
      System.out.println(colors);
    }
  }

  /**
   * A better version of the rainbow class using an unmodifiable set.
   * 
   * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
   * @version $Revision: 1.3 $
   */
  public static class RainbowBetter {
    /** The valid colors of the rainbow. */
    public static final Set VALID_COLORS;

    static {
      Set temp = new HashSet();
      temp.add(Color.red);
      temp.add(Color.orange);
      temp.add(Color.yellow);
      temp.add(Color.green);
      temp.add(Color.blue);
      temp.add(Color.decode("#4B0082")); // indigo
      temp.add(Color.decode("#8A2BE2")); // violet
      VALID_COLORS = Collections.unmodifiableSet(temp);
    }

    /**
     * Some demo method.
     */
    public static final void someMethod() {
      Set colors = RainbowBetter.VALID_COLORS;
      colors.add(Color.black); // <= exception here
      System.out.println(colors);
    }
  }
}

/* ########## End of File ########## */

1.	Collections.min with Comparator
2.	Minimum and maximum number in array
3.	Shuffling the Elements of a List or Array: use Collections.shuffle() to randomly reorder the elements in a list
4.	Shuffle the elements in the array
5.	Create an empty collection object
6.	Collections.reverse
7.	Use Collections.sort to sort custom class and user defined Comparator
8.	Collections.shuffle to shuffle a list
9.	Collections.fill
10.	Use Collections.shuffle to shuffle list
11.	Making a Collection Read-Only
12.	Shuffle generic list
13.	Create List containing n Copies of Specified Object Example
14.	Create and demonstrate an immutable collection.
15.	Sort and Search a LinkedList.
16.	Finding an Element in a Sorted List
17.	Use reverse(), rotate(), and shuffle().
18.	This program demonstrates the random shuffle and sort algorithms

Demonstrates the use of final collections : Collections « Collections Data Structure « Java

Related examples in the same category