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Collection1.javaAPI DocExample5361Mon Apr 06 18:10:26 BST 1998c08.newcollections

Collection1.java

//: Collection1.java
//////////////////////////////////////////////////
// Copyright (c) Bruce Eckel, 1998
// Source code file from the book "Thinking in Java"
// All rights reserved EXCEPT as allowed by the
// following statements: You can freely use this file
// for your own work (personal or commercial),
// including modifications and distribution in
// executable form only. Permission is granted to use
// this file in classroom situations, including its
// use in presentation materials, as long as the book
// "Thinking in Java" is cited as the source. 
// Except in classroom situations, you cannot copy
// and distribute this code; instead, the sole
// distribution point is http://www.BruceEckel.com 
// (and official mirror sites) where it is
// freely available. You cannot remove this
// copyright and notice. You cannot distribute
// modified versions of the source code in this
// package. You cannot use this file in printed
// media without the express permission of the
// author. Bruce Eckel makes no representation about
// the suitability of this software for any purpose.
// It is provided "as is" without express or implied
// warranty of any kind, including any implied
// warranty of merchantability, fitness for a
// particular purpose or non-infringement. The entire
// risk as to the quality and performance of the
// software is with you. Bruce Eckel and the
// publisher shall not be liable for any damages
// suffered by you or any third party as a result of
// using or distributing software. In no event will
// Bruce Eckel or the publisher be liable for any
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// indirect, special, consequential, incidental, or
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// possibility of such damages. Should the software
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// think you've found an error, please email all
// modified files with clearly commented changes to:
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// address for non-code errors found in the book.)
/////////////////////////////////////////////////

// Things you can do with all Collections
package c08.newcollections;
import java.util.*;

public class Collection1 {
  // Fill with 'size' elements, start
  // counting at 'start':
  public static Collection 
  fill(Collection c, int start, int size) {
    for(int i = start; i < start + size; i++)
      c.add(Integer.toString(i));
    return c;
  }
  // Default to a "start" of 0:
  public static Collection 
  fill(Collection c, int size) {
    return fill(c, 0, size);
  }
  // Default to 10 elements:
  public static Collection fill(Collection c) {
    return fill(c, 0, 10);
  }
  // Create & upcast to Collection:
  public static Collection newCollection() {
    return fill(new ArrayList());
    // ArrayList is used for simplicity, but it's
    // only seen as a generic Collection 
    // everywhere else in the program.
  }
  // Fill a Collection with a range of values:
  public static Collection 
  newCollection(int start, int size) {
    return fill(new ArrayList(), start, size);
  }
  // Moving through a List with an iterator:
  public static void print(Collection c) {
    for(Iterator x = c.iterator(); x.hasNext();)
      System.out.print(x.next() + " ");
    System.out.println();
  }    
  public static void main(String[] args) {
    Collection c = newCollection();
    c.add("ten");
    c.add("eleven");
    print(c);
    // Make an array from the List:
    Object[] array = c.toArray(); 
    // Make a String array from the List:
    String[] str = 
      (String[])c.toArray(new String[1]);
    // Find max and min elements; this means
    // different things depending on the way
    // the Comparable interface is implemented:
    System.out.println("Collections.max(c) = " +
      Collections.max(c));
    System.out.println("Collections.min(c) = " +
      Collections.min(c));
    // Add a Collection to another Collection
    c.addAll(newCollection());
    print(c);
    c.remove("3"); // Removes the first one
    print(c);
    c.remove("3"); // Removes the second one
    print(c);
    // Remove all components that are in the
    // argument collection:
    c.removeAll(newCollection());
    print(c);
    c.addAll(newCollection());
    print(c);
    // Is an element in this Collection?
    System.out.println(
      "c.contains(\"4\") = " + c.contains("4"));
    // Is a Collection in this Collection?
    System.out.println(
      "c.containsAll(newCollection()) = " + 
      c.containsAll(newCollection()));
    Collection c2 = newCollection(5, 3);
    // Keep all the elements that are in both
    // c and c2 (an intersection of sets):
    c.retainAll(c2);
    print(c);
    // Throw away all the elements in c that
    // also appear in c2:
    c.removeAll(c2);
    System.out.println("c.isEmpty() = " +
      c.isEmpty());
    c = newCollection();
    print(c);
    c.clear(); // Remove all elements
    System.out.println("after c.clear():");
    print(c);
  }
} ///:~