edu.colorado.collections
Class Table

java.lang.Object
  edu.colorado.collections.Table

public class Table
extends java.lang.Object

A Table is an open-address hash table with a fixed capacity. The purpose is to show students how an open-address hash table is implemented. Programs should generally use java.util.Hashtable rather than this hash table.

Java Source Code for this class:

http://www.cs.colorado.edu/~main/edu/colorado/collections/Table.java

Constructor Summary

Table(int capacity)
Initialize an empty table with a specified capacity.

Method Summary

boolean	containsKey(java.lang.Object key) Determines whether a specified key is in this table.
java.lang.Object	get(java.lang.Object key) Retrieves an object for a specified key.
java.lang.Object	put(java.lang.Object key, java.lang.Object element) Add a new element to this table, using the specified key.
java.lang.Object	remove(java.lang.Object key) Removes an object for a specified key.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Table

public Table(int capacity)

Initialize an empty table with a specified capacity.

Parameters:

capacity - the capacity for this new open-address hash table

Postcondition:

This table is empty and has the specified capacity.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for the specified capacity.

Method Detail

containsKey

public boolean containsKey(java.lang.Object key)

Determines whether a specified key is in this table.

Parameters:

key - the non-null key to look for

Precondition:

key cannot be null.

Returns:

truefalse otherwise. Note that key.equals( ) is used to compare the key to the keys that are in the table.

Throws:

java.lang.NullPointerException - Indicates that key is null.

get

public java.lang.Object get(java.lang.Object key)

Retrieves an object for a specified key.

Parameters:

key - the non-null key to look for

Precondition:

key cannot be null.

Returns:

a reference to the object with the specified keykey.equals( ) is used to compare the key to the keys that are in the table.

Throws:

java.lang.NullPointerException - Indicates that key is null.

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object element)

Add a new element to this table, using the specified key.

Parameters:

key - the non-null key to use for the new element

element - the new element that’s being added to this table

Precondition:

If there is not already an element with the specified key, then this table’s size must be less than its capacity (i.e., size() < capacity()). Also, neither key nor element is null.

Postcondition:

If this table already has an object with the specified key, then that object is replaced by element, and the return value is a reference to the replaced object. Otherwise, the new element is added with the specified key and the return value is null.

Throws:

java.lang.IllegalStateException - Indicates that there is no room for a new object in this table.

java.lang.NullPointerException - Indicates that key or element is null.

remove

public java.lang.Object remove(java.lang.Object key)

Removes an object for a specified key.

Parameters:

key - the non-null key to look for

Precondition:

key cannot be null.

Postcondition:

If an object was found with the specified key, then that object has been removed from this table and a copy of the removed object is returned; otherwise, this table is unchanged and the null reference is returned. Note that key.equals( ) is used to compare the key to the keys that are in the table.

Throws:

java.lang.NullPointerException - Indicates that key is null.