Java Collections Framework - Building Java Programs: A Back to Basics Approach - page 678

Table 11.1 Useful Methods of the Collection Interface

Method Description

add(element) Adds the specified element to this collection
addAll(collection) Adds all elements from the given collection to this collection
clear() Removes all elements from this collection
contains(element) Returns true if this collection contains the given element
containsAll(collection) Returns true if this collection contains all elements of the
given collection

Returns true if this collection contains no elements isEmpty()

Returns an object that can be used to traverse the elements
of this collection

iterator()

Removes one occurrence of the specified element, if it is
contained in this collection

remove(element)

Removes all elements of the given collection from this
collection

removeAll(collection)

Removes all elements not found in the given collection from
this collection

retainAll(collection)

Returns the number of elements in this collection

size()

Returns an array containing the elements of this collection toArray()

The java.util package contains an interface called Collection that is imple-
mented by all collections except Map . This interface specifies the operations that most
collections support. Table 11.1 lists those operations.
The Collection interface is extended and implemented by the other interfaces and
classes in the Java Collections Framework. Figure 11.1 summarizes the various inter-
faces and the classes that implement them, all of which will be discussed in this chapter.

LinkedList versus ArrayList
Now we'll look at a collection called LinkedList and compare and contrast it with
ArrayList .

<<interface>>
Collection

<<interface>>
Map

<<interface>>
List

<<interface>>
Set

ArrayList LinkedList HashSet TreeSet HashMap TreeMap

Figure 11.1

An abridged view of the Java Collections Framework