In the Java programming language, collections are objects that group multiple elements into a single unit. Collections let you store, retrieve, and manipulate data, and transmit data from one method to another.

• Algorithms
• Interfaces

• copy1.java finds the maximum value in the list. For supporting information see Using Collections with JDK 1.2.
  
  
• iterator2.java shows how to safely modify a list while iterating over it. For supporting information see Using Collections with JDK 1.2.
  
  
• map1.java sorts a HashSet using both a natural and comparative sorting order. For supporting information see Using Collections with JDK 1.2.
  
  
• max1.java copies one list to another, overwriting the elements in the target list. For supporting information see Using Collections with JDK 1.2.
  
  
• Perm2.java prints permutation groups, which are stored as values in a Map object in the form of List objects. For supporting information see The Java Tutorial Continued: Collections.
  
  
• PhoneList.java shows how to use a linked hash map to maintain a phone list. For supporting information see New to Java Programming Supplement, July 2002.
  
  
• retro1.java illustrates collection methods for migrating old code to the Collections Framework. For supporting information see Using Collections with JDK 1.2.
  
  
• RunArrayList.java extends AbstractList to store elements in slots, with each slot representing a range of contiguous element indices where all indices in the slot refer to the same element. For supporting information see Using Collections with JDK 1.2.
  
  
• search1.java generates random numbers and adds them to a list. For supporting information see Using Collections with JDK 1.2.
  
  
• serial1.java and serial2.java write a HashMap object to a file test.ser and then restore it. For supporting information see Using Collections with JDK 1.2.
  
  
• shuffle1.java takes a list and scrambles it using an internally-supplied random number generator. For supporting information see Using Collections with JDK 1.2.
  
  
• Sort.java prints its arguments in alphabetical order. For supporting information see The Java Tutorial Continued: Collections.
  
  
• sort1.java sorts an ArrayList using both a natural and comparative sorting order. For supporting information see Using Collections with JDK 1.2.
  
  
• StringArrayList.java subclasses the ArrayList class and implements the subclass to accept only strings in its list. For supporting information see Using Collections with JDK 1.2.
  
  
• sync1.java shows how to use a collection in a thread-safe manner. For supporting information see Using Collections with JDK 1.2.
  
  
• test.java orders a list using the Comparable interface. For supporting information see Using Collections with JDK 1.2.
  
  
• wrapper1.java and wrapper2.java illustrate the fixed size property of collections. For supporting information see Using Collections with JDK 1.2.

Interfaces

• CreatingCollections.java creates a list and iterates through it. For supporting information see New to Java Programming Supplement, March 2002.
  
  
• Deal.java generates hands from a 52 card deck. For supporting information see The Java Tutorial Continued: Collections.
  
  
• FindDups.java takes words in its argument list and prints out any duplicate words, the number of distinct words, and a list of the words with duplicates eliminated. For supporting information see The Java Tutorial Continued: Collections.
  
  
• FindDups2.java finds the words in the argument list that occur once, that occur more than once, and does not print out duplicate words repeatedly. For supporting information see The Java Tutorial Continued: Collections.
  
  
• Freq.java generates a frequency table of the words found in its argument list. For supporting information see The Java Tutorial Continued: Collections.
  
  
• Name.java compares names and returns a value indicating the comparison results: negative integer for less than, zero for equal to, or positive integer for greater than. For supporting information see The Java Tutorial Continued: Collections.
  
  
• Perm.java implements a bucket sort. For supporting information see The Java Tutorial Continued: Collections.
  
  
• Shuffle.java prints words in its argument list in random order. For supporting information see The Java Tutorial Continued: Collections.