java.lang.reflect

Class Field

Implemented Interfaces:
Member

public final class Field
extends AccessibleObject
implements Member

Fields inherited from interface java.lang.reflect.Member

DECLARED, PUBLIC

Method Summary

boolean
equals(Object fld)
Determine whether this Object is semantically equal to another Object.
Object
get(Object obj)
boolean
getBoolean(Object obj)
byte
getByte(Object obj)
char
getChar(Object obj)
Class
getDeclaringClass()
Gets the class that declared this member.
double
getDouble(Object obj)
float
getFloat(Object obj)
int
getInt(Object obj)
long
getLong(Object obj)
int
getModifiers()
Gets the modifiers this member uses.
String
getName()
Gets the simple name of this member.
short
getShort(Object obj)
Class
getType()
int
hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int.
void
set(Object object, Object value)
void
setBoolean(Object obj, boolean b)
void
setByte(Object obj, byte b)
void
setChar(Object obj, char c)
void
setDouble(Object obj, double d)
void
setFloat(Object obj, float f)
void
setInt(Object obj, int i)
void
setLong(Object obj, long l)
void
setShort(Object obj, short s)
String
toString()
Convert this Object to a human-readable String.

Methods inherited from class java.lang.reflect.AccessibleObject

isAccessible, setAccessible, setAccessible

Methods inherited from class java.lang.Object

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

Method Details

equals

public boolean equals(Object fld)
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

get

public Object get(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getBoolean

public boolean getBoolean(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getByte

public byte getByte(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getChar

public char getChar(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getDeclaringClass

public Class getDeclaringClass()
Gets the class that declared this member. This is not the class where this method was called, or even the class where this Member object came to life, but the class that declares the member this represents.
Specified by:
getDeclaringClass in interface Member
Returns:
the class that declared this member

getDouble

public double getDouble(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getFloat

public float getFloat(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getInt

public int getInt(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getLong

public long getLong(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getModifiers

public int getModifiers()
Gets the modifiers this member uses. Use the Modifier class to interpret the values.
Specified by:
getModifiers in interface Member
Returns:
an integer representing the modifiers to this Member
See Also:
Modifier

getName

public String getName()
Gets the simple name of this member. This will be a valid Java identifier, with no qualification.
Specified by:
getName in interface Member
Returns:
the name of this member

getShort

public short getShort(Object obj)
            throws IllegalArgumentException,
                   IllegalAccessException

getType

public Class getType()

hashCode

public 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

set

public void set(Object object,
                Object value)
            throws IllegalArgumentException,
                   IllegalAccessException

setBoolean

public void setBoolean(Object obj,
                       boolean b)
            throws IllegalArgumentException,
                   IllegalAccessException

setByte

public void setByte(Object obj,
                    byte b)
            throws IllegalArgumentException,
                   IllegalAccessException

setChar

public void setChar(Object obj,
                    char c)
            throws IllegalArgumentException,
                   IllegalAccessException

setDouble

public void setDouble(Object obj,
                      double d)
            throws IllegalArgumentException,
                   IllegalAccessException

setFloat

public void setFloat(Object obj,
                     float f)
            throws IllegalArgumentException,
                   IllegalAccessException

setInt

public void setInt(Object obj,
                   int i)
            throws IllegalArgumentException,
                   IllegalAccessException

setLong

public void setLong(Object obj,
                    long l)
            throws IllegalArgumentException,
                   IllegalAccessException

setShort

public void setShort(Object obj,
                     short s)
            throws IllegalArgumentException,
                   IllegalAccessException

toString

public 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

Copyright (C) 1998, 1999, 2000, 2001, 2003 Free Software Foundation This file is part of libgcj. This software is copyrighted work licensed under the terms of the Libgcj License. Please consult the file "LIBGCJ_LICENSE" for details.