Docjar: A Java Source and Docuemnt Enginecom.*    java.*    javax.*    org.*    all    new    plug-in

Quick Search    Search Deep

com.ibatis.sqlmap.engine.cache
Class CacheKey  view CacheKey download CacheKey.java

java.lang.Object
  extended bycom.ibatis.sqlmap.engine.cache.CacheKey

public class CacheKey
extends java.lang.Object

Hash value generator for cache keys


Field Summary
private  long checksum
           
private  int count
           
private static int DEFAULT_HASHCODE
           
private static int DEFAULT_MULTIPLYER
           
private  int hashcode
           
private  int multiplier
           
private  java.util.List paramList
           
 
Constructor Summary
CacheKey()
          Default constructor
CacheKey(int initialNonZeroOddNumber)
          Costructor that supplies an initial hashcode
CacheKey(int initialNonZeroOddNumber, int multiplierNonZeroOddNumber)
          Costructor that supplies an initial hashcode and multiplier
 
Method Summary
 boolean equals(java.lang.Object object)
          Determine whether this Object is semantically equal to another Object.
 int hashCode()
          Get a value that represents this Object, as uniquely as possible within the confines of an int.
 java.lang.String toString()
          Convert this Object to a human-readable String.
 CacheKey update(int x)
          Updates this object with new information based on an int value
 CacheKey update(java.lang.Object object)
          Updates this object with new information based on an object
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

DEFAULT_MULTIPLYER

private static final int DEFAULT_MULTIPLYER
See Also:
Constant Field Values

DEFAULT_HASHCODE

private static final int DEFAULT_HASHCODE
See Also:
Constant Field Values

multiplier

private int multiplier

hashcode

private int hashcode

checksum

private long checksum

count

private int count

paramList

private java.util.List paramList
Constructor Detail

CacheKey

public CacheKey()
Default constructor


CacheKey

public CacheKey(int initialNonZeroOddNumber)
Costructor that supplies an initial hashcode


CacheKey

public CacheKey(int initialNonZeroOddNumber,
                int multiplierNonZeroOddNumber)
Costructor that supplies an initial hashcode and multiplier

Method Detail

update

public CacheKey update(int x)
Updates this object with new information based on an int value


update

public CacheKey update(java.lang.Object object)
Updates this object with new information based on an object


equals

public boolean equals(java.lang.Object object)
Description copied from class: java.lang.Object
Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

  • It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
  • It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
  • It must be reflexive. a.equals(a) must always be true.
  • It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
  • a.equals(null) must be false.
  • It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.


hashCode

public int hashCode()
Description copied from class: java.lang.Object
Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

  • Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
  • It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)


toString

public java.lang.String toString()
Description copied from class: java.lang.Object
Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).