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Class java.lang.reflect.Field

java.lang.Object
   |
   +----java.lang.reflect.Field

public final class Field

extends Object

implements Member

A Field permits widening conversions to occur during a get or set access operation, but throws an IllegalArgumentException if a narrowing conversion would occur.

See Also:

Member, Class, getFields, getField, getDeclaredFields, getDeclaredField

equals(Object)

Compares this Field against the specified object.

get(Object)

Returns the value of the field represented by this Field, on the specified object.

getBoolean(Object)

Get the value of a field as a boolean on specified object.

getByte(Object)

Get the value of a field as a byte on specified object.

getChar(Object)

Get the value of a field as a char on specified object.

getDeclaringClass()

Returns the Class object representing the class or interface that declares the field represented by this Field object.

getDouble(Object)

Get the value of a field as a double on specified object.

getFloat(Object)

Get the value of a field as a float on specified object.

getInt(Object)

Get the value of a field as a int on specified object.

getLong(Object)

Get the value of a field as a long on specified object.

getModifiers()

Returns the Java language modifiers for the field represented by this Field object, as an integer.

getName()

Returns the name of the field represented by this Field object.

getShort(Object)

Get the value of a field as a short on specified object.

getType()

Returns a Class object that identifies the declared type for the field represented by this Field object.

hashCode()

Returns a hashcode for this Field.

set(Object, Object)

Sets the field represented by this Field object on the specified object argument to the specified new value.

setBoolean(Object, boolean)

Set the value of a field as a boolean on specified object.

setByte(Object, byte)

Set the value of a field as a byte on specified object.

setChar(Object, char)

Set the value of a field as a char on specified object.

setDouble(Object, double)

Set the value of a field as a double on specified object.

setFloat(Object, float)

Set the value of a field as a float on specified object.

setInt(Object, int)

Set the value of a field as an int on specified object.

setLong(Object, long)

Set the value of a field as a long on specified object.

setShort(Object, short)

Set the value of a field as a short on specified object.

toString()

Return a string describing this Field.

  public Class getDeclaringClass()

Returns the Class object representing the class or interface that declares the field represented by this Field object.

  public String getName()

Returns the name of the field represented by this Field object.

  public int getModifiers()

Returns the Java language modifiers for the field represented by this Field object, as an integer. The Modifier class should be used to decode the modifiers.

See Also:

Modifier

  public Class getType()

Returns a Class object that identifies the declared type for the field represented by this Field object.

  public boolean equals(Object obj)

Compares this Field against the specified object. Returns true if the objects are the same. Two Fields are the same if they were declared by the same class and have the same name and type.

Overrides:

equals in class Object

  public int hashCode()

Returns a hashcode for this Field. This is computed as the exclusive-or of the hashcodes for the underlying field's declaring class name and its name.

Overrides:

hashCode in class Object

  public String toString()

Return a string describing this 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.

Overrides:

toString in class Object

  public Object get(Object obj) throws IllegalArgumentException, IllegalAccessException

Returns the value of the field represented by this 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 object 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 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.

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.

  public boolean getBoolean(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a boolean on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public byte getByte(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a byte on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public char getChar(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a char on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public short getShort(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a short on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public int getInt(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a int on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public long getLong(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a long on specified object. If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public float getFloat(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a float on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

  public double getDouble(Object obj) throws IllegalArgumentException, IllegalAccessException

Get the value of a field as a double on specified object.

If the field value cannot be converted to the return type by a widening conversion, throws an IllegalArgumentException.

See Also:

get

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

Sets the field represented by this 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 object 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.

The field is set to the possibly unwrapped and widened new value.

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

Set the value of a field as a boolean on specified object.

See Also:

set

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

Set the value of a field as a byte on specified object.

See Also:

set

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

Set the value of a field as a char on specified object.

See Also:

set

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

Set the value of a field as a short on specified object.

See Also:

set

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

Set the value of a field as an int on specified object.

See Also:

set

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

Set the value of a field as a long on specified object.

See Also:

set

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

Set the value of a field as a float on specified object.

See Also:

set

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

Set the value of a field as a double on specified object.

See Also:

set

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