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Freenet.support
Class StringKey  view StringKey download StringKey.java

java.lang.Object
  extended byFreenet.support.StringKey
All Implemented Interfaces:
Freenet.Key, java.io.Serializable

public class StringKey
extends java.lang.Object
implements Freenet.Key

An implementation of the Key interface for Strings

Version:
1.0

Field Summary
(package private)  java.lang.String value
           
 
Constructor Summary
StringKey(java.lang.String value)
           
 
Method Summary
 char charAt(int p)
           
private  int charComp(char c, char c1, char c2)
           
 boolean compare(Freenet.Key kk1, Freenet.Key kk2)
          Compares two other keys to this one to determine which is closer
 boolean equals(java.lang.Object t)
          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.
 boolean lessThan(Freenet.Key k)
           
 java.lang.String toString()
          Convert this Object to a human-readable String.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

value

java.lang.String value
Constructor Detail

StringKey

public StringKey(java.lang.String value)
Method Detail

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)

Specified by:
hashCode in interface Freenet.Key

charAt

public char charAt(int p)

equals

public boolean equals(java.lang.Object t)
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.

Specified by:
equals in interface Freenet.Key

lessThan

public boolean lessThan(Freenet.Key k)
                 throws Freenet.KeyException
Specified by:
lessThan in interface Freenet.Key

compare

public boolean compare(Freenet.Key kk1,
                       Freenet.Key kk2)
                throws Freenet.KeyException
Description copied from interface: Freenet.Key
Compares two other keys to this one to determine which is closer

Specified by:
compare in interface Freenet.Key

charComp

private int charComp(char c,
                     char c1,
                     char c2)

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()).