java.nio.charset

Class Charset

Implemented Interfaces:
Comparable<T>
Known Direct Subclasses:
IconvCharset

public abstract class Charset
extends Object
implements Comparable<T>

Since:
1.4

Constructor Summary

Charset(String canonicalName, String[] aliases)

Method Summary

static SortedMap
Charset> availableCharsets()
Set
aliases()
boolean
canEncode()
int
compareTo(Charset other)
abstract boolean
contains(Charset cs)
CharBuffer
decode(ByteBuffer bb)
static Charset
defaultCharset()
Returns the system default charset.
String
displayName()
String
displayName(Locale locale)
ByteBuffer
encode(String str)
ByteBuffer
encode(CharBuffer cb)
boolean
equals(Object ob)
Determine whether this Object is semantically equal to another Object.
static Charset
forName(String charsetName)
Returns the Charset instance for the charset of the given name.
int
hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int.
boolean
isRegistered()
static boolean
isSupported(String charsetName)
String
name()
abstract CharsetDecoder
newDecoder()
abstract CharsetEncoder
newEncoder()
String
toString()
Convert this Object to a human-readable String.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Charset

protected Charset(String canonicalName,
                  String[] aliases)

Method Details

Charset> availableCharsets

public static SortedMapCharset> availableCharsets()

aliases

public final Set aliases()

canEncode

public boolean canEncode()

compareTo

public final int compareTo(Charset other)

contains

public abstract boolean contains(Charset cs)

decode

public final CharBuffer decode(ByteBuffer bb)

defaultCharset

public static Charset defaultCharset()
Returns the system default charset. This may be set by the user or VM with the file.encoding property.
Since:
1.5

displayName

public String displayName()

displayName

public String displayName(Locale locale)

encode

public final ByteBuffer encode(String str)

encode

public final ByteBuffer encode(CharBuffer cb)

equals

public final boolean equals(Object ob)
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 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 NullPointerException.

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

The default implementation returns this == o.

Overrides:
equals in interface Object
Parameters:
Returns:
whether this Object is semantically equal to another

forName

public static Charset forName(String charsetName)
Returns the Charset instance for the charset of the given name.
Parameters:
charsetName -
Returns:
the Charset instance for the indicated charset
Throws:
UnsupportedCharsetException - if this VM does not support the charset of the given name.
IllegalCharsetNameException - if the given charset name is legal.
IllegalArgumentException - if charsetName is null.

hashCode

public final int hashCode()
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 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)

Overrides:
hashCode in interface Object
Returns:
the hash code for this Object

isRegistered

public final boolean isRegistered()

isSupported

public static boolean isSupported(String charsetName)

name

public final String name()

newDecoder

public abstract CharsetDecoder newDecoder()

newEncoder

public abstract CharsetEncoder newEncoder()

toString

public final String toString()
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() and such.

It is typical, but not required, to ensure that this method never completes abruptly with a 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()).

Overrides:
toString in interface Object
Returns:
the String representing this Object, which may be null

Charset.java -- Copyright (C) 2002, 2004, 2005, 2007 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.