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List (interface) |
Order is the most important feature of a List; it promises to maintain elements in a particular sequence. List adds a number of methods to Collection that allow insertion and removal of elements in the middle of a List. (This is recommended only for a LinkedList.) A List will produce a ListIterator, and using this you can traverse the List in both directions, as well as insert and remove elements in the middle of the list (again, recommended only for a LinkedList). |
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ArrayList* |
A List backed by an array. Use instead of Vector as a general-purpose object holder. Allows rapid random access to elements, but is slow when inserting and removing elements from the middle of a list. ListIterator should be used only for back-and-forth traversal of an ArrayList, but not for inserting and removing elements, which is expensive compared to LinkedList. |
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LinkedList |
Provides optimal sequential access, with inexpensive insertions and deletions from the middle of the list. Relatively slow for random access. (Use ArrayList instead.) Also has addFirst( ), addLast( ), getFirst( ), getLast( ), removeFirst( ), and removeLast( ) (which are not defined in any interfaces or base classes) to allow it to be used as a stack, a queue, and a dequeue. |
The methods in the following example each cover a different group of activities: things that every list can do (basicTest( )), moving around with an Iterator (iterMotion( )) versus changing things with an Iterator (iterManipulation( )), seeing the effects of List manipulation (testVisual( )), and operations available only to LinkedLists.
//: List1.java
// Things you can do with Lists
package c08.newcollections;
import java.util.*;
public class List1
// You can use an Iterator, just as with a
// Collection, but you can also use random
// access with get():
public static void print(List a)
static boolean b;
static Object o;
static int i;
static Iterator it;
static ListIterator lit;
public static void basicTest(List a)
public static void iterMotion(List a)
public static void iterManipulation(List a)
public static void testVisual(List a)
// There are some things that only
// LinkedLists can do:
public static void testLinkedList()
public static void main(String args[])
} ///:~
In basicTest( ) and iterMotion( ) the calls are simply made to show the proper syntax, and while the return value is captured, it is not used. In some cases, the return value isn't captured since it isn't typically used. You should look up the full usage of each of these methods in your online documentation before you use them.
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