simplehashtable.html

发布/订阅系统路由重配算法,可应用于ad hoc环境

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<A NAME="SimpleHashtable()"><!-- --></A><H3>
SimpleHashtable</H3>
<PRE>
public <B>SimpleHashtable</B>()</PRE>
<DL>
<DD>Constructs a new <code>SimpleHashtable</code> object with the
 following default parameters:
 <code>minCapacity = 10</code>,
 <code>maxCapacity = Integer.MAX_VALUE</code>,
 <code>minLoadFactor = 0.0f</code>,
 <code>maxLoadFactor = 0.75f</code> and
 <code>capacityRate = 2.0f</code>.
<P>
</DL>
<HR>

<A NAME="SimpleHashtable(int, float)"><!-- --></A><H3>
SimpleHashtable</H3>
<PRE>
public <B>SimpleHashtable</B>(int&nbsp;minCapacity,
                       float&nbsp;maxLoadFactor)</PRE>
<DL>
<DD>Constructs a new <code>SimpleHashtable</code> object with the
 specified and following default parameters:
 <code>maxCapacity = Integer.MAX_VALUE</code>,
 <code>minLoadFactor = 0.0f</code> and
 <code>capacityRate = 2.0f</code>.
<P>
<DT><B>Parameters:</B><DD><CODE>minCapacity</CODE> - the minimum capacity of the internal bucket array.<DD><CODE>maxLoadFactor</CODE> - the maximum tolarated load factor.
<DT><B>Throws:</B>
<DD><CODE>java.lang.IllegalArgumentException</CODE> - if <code>minCapacity</code> is
         less than <code>1</code> or if <code>maxLoadFactor</code>
         is equal or less than <code>0.0f</code>.</DL>
<HR>

<A NAME="SimpleHashtable(int, int, float, float, float)"><!-- --></A><H3>
SimpleHashtable</H3>
<PRE>
public <B>SimpleHashtable</B>(int&nbsp;minCapacity,
                       int&nbsp;maxCapacity,
                       float&nbsp;minLoadFactor,
                       float&nbsp;maxLoadFactor,
                       float&nbsp;capacityRate)</PRE>
<DL>
<DD>Constructs a new empty <code>SimpleHashtable</code> object with
 the specified parameters. <p>
 
 <code>minCapacity</code> and <code>maxCapacity</code> limit the
 size of the used internal bucket array.
 Note that a too high <code>minCapacity</code> wastes space, while
 a too low <code>maxCapacity</code> leads to hash collisions and
 decreases the performance. <p>
 
 <code>minLoadFactor</code> and <code>maxLoadFactor</code> control
 when the internal bucket array's capacity is adapted and the table 
 is rehashed.
 When the total number of stored entries in the hashtable drops
 below the product of the <code>minLoadFactor</code> and the current
 capacity, the capacity is reduced by <code>capacityRate</code>.
 When the total number of stored entries in the hashtable exceeds
 the product of the <code>maxLoadFactor</code> and the current
 capacity, the capacity is extended by <code>capacityRate</code>.
 Note that the capacity will never fall short of 
 <code>minCapacity</code> or exceed <code>maxCapacity</code>. <p>
 
 Note also that the constructor will check all parameters whether
 they are valid. It is not checked if their combination makes sense.
<P>
<DT><B>Parameters:</B><DD><CODE>minCapacity</CODE> - the minimum capacity of the internal bucket array.<DD><CODE>maxCapacity</CODE> - the maximum capacity of the internal bucker array.<DD><CODE>minLoadFactor</CODE> - the minimum tolerated load factor.<DD><CODE>maxLoadFactor</CODE> - the maximum tolarated load factor.<DD><CODE>capacityRate</CODE> - the capacity adaption rate.
<DT><B>Throws:</B>
<DD><CODE>java.lang.IllegalArgumentException</CODE> - if <code>minCapacity</code> or
         <code>maxCapacity</code> are less than <code>1</code>,
         if <code>minLoadFactor</code> is less than <code>0.0f</code>,
         if <code>maxLoadFactor</code> is equal or less than
         <code>0.0f</code> or if <code>capacityRate</code> is 
         equal or less than <code>1.0f</code>.</DL>

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<B>Method Detail</B></FONT></TD>
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<A NAME="rehash(int)"><!-- --></A><H3>
rehash</H3>
<PRE>
protected void <B>rehash</B>(int&nbsp;capacity)</PRE>
<DL>
<DD>Reorganizes the hashtable to use a new internal bucket array of the
 specified capacity. 
 This method is called automatically if the number of stored entries
 drops below the product of minimum load factor and the current
 capacity or if the number of stored entries exceeds the product of
 the maximum load factor and the current capacity.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>capacity</CODE> - the new capacity of the internal bucket array.</DL>
</DD>
</DL>
<HR>

<A NAME="put(java.lang.Object, java.lang.Object)"><!-- --></A><H3>
put</H3>
<PRE>
public java.lang.Object <B>put</B>(java.lang.Object&nbsp;key,
                            java.lang.Object&nbsp;value)</PRE>
<DL>
<DD>Maps the specified <code>key</code> to the specified 
 <code>value</code> in this hashtable. Both the key and the 
 value can be <code>null</code>. <p>

 The value can be retrieved by calling the <code>get</code> method 
 with a key that is equal to the original key. <p>
 
 The table is rehashed, when the <code>put</code> operation causes
 the number of entries to exceed the product of the maximum load factor
 and the current capacity.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - the hashtable key.<DD><CODE>value</CODE> - the value.
<DT><B>Returns:</B><DD>the previous value of the specified key in this hashtable,
         or <code>null</code> if it did not have one.<DT><B>See Also:</B><DD><A HREF="../util/SimpleHashtable.html#get(java.lang.Object)"><CODE>get(Object)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="remove(java.lang.Object)"><!-- --></A><H3>
remove</H3>
<PRE>
public java.lang.Object <B>remove</B>(java.lang.Object&nbsp;key)</PRE>
<DL>
<DD>Removes the key (and its corresponding value) from this hashtable. 
 This method does nothing if the key is not in the hashtable. <p>
 
 The table is rehashed, when the <code>remove</code> operation causes
 the number of entries to drops below the product of the minimum load 
 factor and the current capacity.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - the key that needs to be removed.
<DT><B>Returns:</B><DD>the value to which the key had been mapped in this hashtable,
          or <code>null</code> if the key did not have a mapping.</DL>
</DD>
</DL>
<HR>

<A NAME="get(java.lang.Object)"><!-- --></A><H3>
get</H3>
<PRE>
public java.lang.Object <B>get</B>(java.lang.Object&nbsp;key)</PRE>
<DL>
<DD>Returns the value to which the specified key is mapped in this hashtable.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - a key in the hashtable.
<DT><B>Returns:</B><DD>the value to which the key is mapped in this hashtable or
         <code>null</code> if the key is not mapped to any value in
         this hashtable.<DT><B>See Also:</B><DD><A HREF="../util/SimpleHashtable.html#put(java.lang.Object, java.lang.Object)"><CODE>put(Object, Object)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="containsKey(java.lang.Object)"><!-- --></A><H3>
containsKey</H3>
<PRE>
public boolean <B>containsKey</B>(java.lang.Object&nbsp;key)</PRE>
<DL>
<DD>Tests if the specified object is a key in this hashtable.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - the object to test.
<DT><B>Returns:</B><DD><code>true</code> if and only if the specified object 
          is a key in this hashtable, as determined by the 
          <tt>equals</tt> method; <code>false</code> otherwise.<DT><B>See Also:</B><DD><A HREF="../util/SimpleHashtable.html#contains(java.lang.Object)"><CODE>contains(Object)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="contains(java.lang.Object)"><!-- --></A><H3>
contains</H3>
<PRE>
public boolean <B>contains</B>(java.lang.Object&nbsp;value)</PRE>
<DL>
<DD>Tests if the specified value is stored in this hashtable.
 This operation is more expensive than the <code>containsKey</code>
 method, since it sequentially searches the table. <p>

 Note that this method is identical in functionality to 
 <code>containsValue</code>.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - the value to search for.
<DT><B>Returns:</B><DD><code>true</code> if and only if some key maps to the
         <code>value</code> argument in this hashtable as 
         determined by the <tt>equals</tt> method;
         <code>false</code> otherwise.<DT><B>See Also:</B><DD><A HREF="../util/SimpleHashtable.html#containsKey(java.lang.Object)"><CODE>containsKey(Object)</CODE></A>, 
<A HREF="../util/SimpleHashtable.html#containsValue(java.lang.Object)"><CODE>containsValue(Object)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="containsValue(java.lang.Object)"><!-- --></A><H3>
containsValue</H3>
<PRE>
public boolean <B>containsValue</B>(java.lang.Object&nbsp;value)</PRE>
<DL>
<DD>Tests if the specified value is stored in this hashtable.
 This operation is more expensive than the <code>containsKey</code>
 method, since it sequentially searches the table. <p>

 Note that this method is identical in functionality to 
 <code>contains</code>.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - the value to search for.
<DT><B>Returns:</B><DD><code>true</code> if and only if some key maps to the
         <code>value</code> argument in this hashtable as 
         determined by the <tt>equals</tt> method;
         <code>false</code> otherwise.<DT><B>See Also:</B><DD><A HREF="../util/SimpleHashtable.html#containsKey(java.lang.Object)"><CODE>containsKey(Object)</CODE></A>, 
<A HREF="../util/SimpleHashtable.html#contains(java.lang.Object)"><CODE>contains(Object)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="isEmpty()"><!-- --></A><H3>
isEmpty</H3>
<PRE>
public boolean <B>isEmpty</B>()</PRE>
<DL>
<DD>Tests if this hashtable stores any entries.
<P>
<DD><DL>

<DT><B>Returns:</B><DD><code>true<code> if this hashtable stores at least one entry;
         otherwise <code>false</code>.</DL>
</DD>
</DL>
<HR>

<A NAME="size()"><!-- --></A><H3>
size</H3>
<PRE>
public int <B>size</B>()</PRE>
<DL>
<DD>Returns the number of entries stored in this hashtable.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>the number of entries stored in this hashtable.</DL>
</DD>
</DL>
<HR>

<A NAME="clear()"><!-- --></A><H3>
clear</H3>
<PRE>
public void <B>clear</B>()</PRE>
<DL>
<DD>Clears this hashtable by replacing the internal bucket arry with
 an empty new one of minimum capacity.
<P>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="keyIterator()"><!-- --></A><H3>
keyIterator</H3>
<PRE>
public <A HREF="../util/ResetableIterator.html" title="interface in util">ResetableIterator</A> <B>keyIterator</B>()</PRE>
<DL>
<DD>Returns a new iterator of the hashtable keys, which is 
 <i>not</i> fail-fast. 
 Use the iterator methods on the returned object to fetch the keys
 sequentially.
 Note that no specific guarantee is made on the order of the elements
 returned.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>an iterator of the hashtable keys.</DL>
</DD>
</DL>
<HR>

<A NAME="valueIterator()"><!-- --></A><H3>
valueIterator</H3>
<PRE>
public <A HREF="../util/ResetableIterator.html" title="interface in util">ResetableIterator</A> <B>valueIterator</B>()</PRE>
<DL>
<DD>Returns a new iterator of the hashtable values, which is 
 <i>not</i> fail-fast. 
 Use the iterator methods on the returned object to fetch the values
 sequentially.
 Note that no specific guarantee is made on the order of the elements
 returned.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>an iterator of the hashtable values.</DL>
</DD>
</DL>
<HR>

<A NAME="entryIterator()"><!-- --></A><H3>
entryIterator</H3>
<PRE>
public <A HREF="../util/ResetableIterator.html" title="interface in util">ResetableIterator</A> <B>entryIterator</B>()</PRE>
<DL>
<DD><DL>
</DL>
</DD>
</DL>
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