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Java Platform 1.2 |
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| SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
java.lang.Object
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+--java.lang.reflect.AccessibleObject
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+--java.lang.reflect.Field
A Field provides information about, and dynamic access to, a
single field of a class or an interface. The reflected field may
be a class (static) field or an instance field.
A Field permits widening conversions to occur during a get or
set access operation, but throws an IllegalArgumentException if a
narrowing conversion would occur.
Member,
Class,
Class.getFields(),
java.lang.Class#getField(),
Class.getDeclaredFields(),
java.lang.Class#getDeclaredField()| Method Summary | |
boolean |
equals(Object obj)
Compares this Field against the specified object. |
Object |
get(Object obj)
Returns the value of the field represented by this Field, on
the specified object. |
boolean |
getBoolean(Object obj)
Gets the value of a field as a boolean on the specified object. |
byte |
getByte(Object obj)
Gets the value of a field as a byte on the specified object. |
char |
getChar(Object obj)
Gets the value of a field as a char on the specified object. |
Class |
getDeclaringClass()
Returns the Class object representing the class or interface
that declares the field represented by this Field object. |
double |
getDouble(Object obj)
Gets the value of a field as a double on the specified object. |
float |
getFloat(Object obj)
Gets the value of a field as a float on the specified object. |
int |
getInt(Object obj)
Gets the value of a field as an int on the specified object. |
long |
getLong(Object obj)
Gets the value of a field as a long on the specified object. |
int |
getModifiers()
Returns the Java language modifiers for the field represented by this Field object, as an integer. |
String |
getName()
Returns the name of the field represented by this Field object. |
short |
getShort(Object obj)
Gets the value of a field as a short on the specified object. |
Class |
getType()
Returns a Class object that identifies the declared type for
the field represented by this Field object. |
int |
hashCode()
Returns a hashcode for this Field. |
void |
set(Object obj,
Object value)
Sets the field represented by this Field object on the
specified object argument to the specified new value. |
void |
setBoolean(Object obj,
boolean z)
Sets the value of a field as a boolean on the specified object. |
void |
setByte(Object obj,
byte b)
Sets the value of a field as a byte on the specified object. |
void |
setChar(Object obj,
char c)
Sets the value of a field as a char on the specified object. |
void |
setDouble(Object obj,
double d)
Sets the value of a field as a double on the specified object. |
void |
setFloat(Object obj,
float f)
Sets the value of a field as a float on the specified object. |
void |
setInt(Object obj,
int i)
Sets the value of a field as an int on the specified object. |
void |
setLong(Object obj,
long l)
Sets the value of a field as a long on the specified object. |
void |
setShort(Object obj,
short s)
Sets the value of a field as a short on the specified object. |
String |
toString()
Returns a string describing this Field. |
| Methods inherited from class java.lang.reflect.AccessibleObject |
isAccessible,
setAccessible,
setAccessible |
| Methods inherited from class java.lang.Object |
clone,
finalize,
getClass,
notify,
notifyAll,
wait,
wait,
wait |
| Method Detail |
public Class getDeclaringClass()
Class object representing the class or interface
that declares the field represented by this Field object.public String getName()
Field object.public int getModifiers()
Field object, as an integer. The Modifier class should
be used to decode the modifiers.Modifierpublic Class getType()
Class object that identifies the declared type for
the field represented by this Field object.public boolean equals(Object obj)
Field against the specified object. Returns
true if the objects are the same. Two Field objects are the same if
they were declared by the same class and have the same name
and type.public int hashCode()
Field. This is computed as the
exclusive-or of the hashcodes for the underlying field's
declaring class name and its name.public String toString()
Field. The format is
the access modifiers for the field, if any, followed
by the field type, followed by a space, followed by
the fully-qualified name of the class declaring the field,
followed by a period, followed by the name of the field.
For example:
public static final int java.lang.Thread.MIN_PRIORITY
private int java.io.FileDescriptor.fd
The modifiers are placed in canonical order as specified by "The Java Language Specification". This is public, protected or private first, and then other modifiers in the following order: static, final, transient, volatile.
public Object get(Object obj)
throws IllegalArgumentException,
IllegalAccessException
Field, on
the specified object. The value is automatically wrapped in an
object if it has a primitive type.
The underlying field's value is obtained as follows:
If the underlying field is a static field, the obj argument
is ignored; it may be null.
Otherwise, the underlying field is an instance field. If the
specified obj argument is null, the method throws a
NullPointerException. If the specified object is not an
instance of the class or interface declaring the underlying
field, the method throws an IllegalArgumentException.
If this Field object enforces Java language access control, and
the underlying field is inaccessible, the method throws an
IllegalAccessException.
If the underlying field is static, the class that declared the
field is initialized if it has not already been initialized.
Otherwise, the value is retrieved from the underlying instance or static field. If the field has a primitive type, the value is wrapped in an object before being returned, otherwise it is returned as is.
If the field is hidden in the type of obj,
the field's value is obtained according to the preceding rules.
public boolean getBoolean(Object obj)
throws IllegalArgumentException,
IllegalAccessException
boolean on the specified object.
This method is equivalent to
((Boolean)get(obj)).booleanValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
boolean by a widening conversion.boolean by a
widening conversion.get(java.lang.Object)
public byte getByte(Object obj)
throws IllegalArgumentException,
IllegalAccessException
byte on the specified object.
This method is equivalent to
((Number)get(obj)).byteValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
byte by a widening conversion.byte by a
widening conversion.get(java.lang.Object)
public char getChar(Object obj)
throws IllegalArgumentException,
IllegalAccessException
char on the specified object.
This method is equivalent to
((Character)get(obj)).charValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
char by a widening conversion.char by a
widening conversion.get(java.lang.Object)
public short getShort(Object obj)
throws IllegalArgumentException,
IllegalAccessException
short on the specified object.
This method is equivalent to
((Number)get(obj)).shortValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
short by a widening conversion.short by a
widening conversion.get(java.lang.Object)
public int getInt(Object obj)
throws IllegalArgumentException,
IllegalAccessException
int on the specified object.
This method is equivalent to
((Number)get(obj)).intValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
int by a widening conversion.int by a
widening conversion.get(java.lang.Object)
public long getLong(Object obj)
throws IllegalArgumentException,
IllegalAccessException
long on the specified object.
This method is equivalent to
((Number)get(obj)).longValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
long by a widening conversion.long by a
widening conversion.get(java.lang.Object)
public float getFloat(Object obj)
throws IllegalArgumentException,
IllegalAccessException
float on the specified object.
This method is equivalent to
((Number)get(obj)).floatValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
float by a widening conversion.float by a
widening conversion.get(java.lang.Object)
public double getDouble(Object obj)
throws IllegalArgumentException,
IllegalAccessException
double on the specified object.
This method is equivalent to
((Number)get(obj)).doubleValue(),
except that an IllegalArgumentException is thrown
if the field value cannot be converted to the type
double by a widening conversion.double by a
widening conversion.get(java.lang.Object)
public void set(Object obj,
Object value)
throws IllegalArgumentException,
IllegalAccessException
Field object on the
specified object argument to the specified new value. The new
value is automatically unwrapped if the underlying field has a
primitive type.
The operation proceeds as follows:
If the underlying field is static, the obj argument is
ignored; it may be null.
Otherwise the underlying field is an instance field. If the
specified object argument is null, the method throws a
NullPointerException. If the specified object argument is not
an instance of the class or interface declaring the underlying
field, the method throws an IllegalArgumentException.
If this Field object enforces Java language access control, and
the underlying field is inaccessible, the method throws an
IllegalAccessException.
If the underlying field is final, the method throws an
IllegalAccessException.
If the underlying field is of a primitive type, an unwrapping
conversion is attempted to convert the new value to a value of
a primitive type. If this attempt fails, the method throws an
IllegalArgumentException.
If, after possible unwrapping, the new value cannot be
converted to the type of the underlying field by an identity or
widening conversion, the method throws an
IllegalArgumentException.
If the underlying field is static, the class that declared the field is initialized if it has not already been initialized.
The field is set to the possibly unwrapped and widened new value.
If the field is hidden in the type of obj,
the field's value is set according to the preceding rules.
public void setBoolean(Object obj,
boolean z)
throws IllegalArgumentException,
IllegalAccessException
boolean on the specified object.
This method is equivalent to
set(obj, zObj),
where zObj is a Boolean object and
zObj.booleanValue() == z.set(java.lang.Object, java.lang.Object)
public void setByte(Object obj,
byte b)
throws IllegalArgumentException,
IllegalAccessException
byte on the specified object.
This method is equivalent to
set(obj, bObj),
where bObj is a Byte object and
bObj.byteValue() == b.set(java.lang.Object, java.lang.Object)
public void setChar(Object obj,
char c)
throws IllegalArgumentException,
IllegalAccessException
char on the specified object.
This method is equivalent to
set(obj, cObj),
where cObj is a Character object and
cObj.charValue() == c.set(java.lang.Object, java.lang.Object)
public void setShort(Object obj,
short s)
throws IllegalArgumentException,
IllegalAccessException
short on the specified object.
This method is equivalent to
set(obj, sObj),
where sObj is a Short object and
sObj.shortValue() == s.set(java.lang.Object, java.lang.Object)
public void setInt(Object obj,
int i)
throws IllegalArgumentException,
IllegalAccessException
int on the specified object.
This method is equivalent to
set(obj, iObj),
where iObj is a Integer object and
iObj.intValue() == i.set(java.lang.Object, java.lang.Object)
public void setLong(Object obj,
long l)
throws IllegalArgumentException,
IllegalAccessException
long on the specified object.
This method is equivalent to
set(obj, lObj),
where lObj is a Long object and
lObj.longValue() == l.set(java.lang.Object, java.lang.Object)
public void setFloat(Object obj,
float f)
throws IllegalArgumentException,
IllegalAccessException
float on the specified object.
This method is equivalent to
set(obj, fObj),
where fObj is a Float object and
fObj.floatValue() == f.set(java.lang.Object, java.lang.Object)
public void setDouble(Object obj,
double d)
throws IllegalArgumentException,
IllegalAccessException
double on the specified object.
This method is equivalent to
set(obj, dObj),
where dObj is a Double object and
dObj.doubleValue() == d.set(java.lang.Object, java.lang.Object)
|
Java Platform 1.2 |
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| SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||