com.jgoodies.binding.value

Class ValueHolder

java.lang.Object

com.jgoodies.common.bean.Bean

com.jgoodies.binding.beans.Model

com.jgoodies.binding.value.AbstractValueModel

com.jgoodies.binding.value.ValueHolder

All Implemented Interfaces:

ValueModel, com.jgoodies.common.bean.ObservableBean, com.jgoodies.common.bean.ObservableBean2, Serializable

public final class ValueHolder
extends AbstractValueModel

A simple ValueModel implementation that holds a generic value. If the value changes, a PropertyChangeEvent is fired that can be observed using a PropertyChangeListener.

Differences in the old and new value can be checked either using == or #equals. The unbound property identityCheckEnabled determines which mechanism is used to check for changes in #setValue(Object). This check can be overridden for individual changes by the boolean parameter in #setValue(Object, boolean).

Constraints: The value is of type Object.

Version:

$Revision: 1.10 $

Author:

Karsten Lentzsch

See Also:

ValueModel, PropertyChangeEvent, PropertyChangeListener, ExtendedPropertyChangeSupport, Serialized Form

Field Summary

Fields inherited from class com.jgoodies.common.bean.Bean

changeSupport

Fields inherited from interface com.jgoodies.binding.value.ValueModel

PROPERTY_VALUE

Constructor Summary

Constructors

Constructor and Description
ValueHolder() Constructs a ValueHolder with null as initial value.
ValueHolder(boolean initialValue) Constructs a ValueHolder with the specified initial boolean value that is converted to a Boolean object.
ValueHolder(double initialValue) Constructs a ValueHolder with the specified initial double value that is converted to a Double object.
ValueHolder(float initialValue) Constructs a ValueHolder with the specified initial float value that is converted to a Float object.
ValueHolder(int initialValue) Constructs a ValueHolder with the specified initial int value that is converted to an Integer object.
ValueHolder(long initialValue) Constructs a ValueHolder with the specified initial long value that is converted to a Long object.
ValueHolder(Object initialValue) Constructs a ValueHolder with the given initial value.
ValueHolder(Object initialValue, boolean checkIdentity) Constructs a ValueHolder with the given initial value.

Method Summary

Methods

Modifier and Type	Method and Description
Object	getValue() Returns the observed value.
boolean	isIdentityCheckEnabled() Answers whether this ValueHolder fires value change events if and only if the old and new value are not the same.
void	setIdentityCheckEnabled(boolean checkIdentity) Sets the comparison that is used to check differences between the old and new value when firing value change events.
void	setValue(Object newValue) Sets a new value.
void	setValue(Object newValue, boolean checkIdentity) Sets a new value.

Methods inherited from class com.jgoodies.binding.value.AbstractValueModel

addValueChangeListener, booleanValue, doubleValue, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, floatValue, getString, intValue, longValue, paramString, removeValueChangeListener, setValue, setValue, setValue, setValue, setValue, toString, valueString

Methods inherited from class com.jgoodies.binding.beans.Model

createPropertyChangeSupport, firePropertyChange

Methods inherited from class com.jgoodies.common.bean.Bean

addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, fireIndexedPropertyChange, fireIndexedPropertyChange, fireIndexedPropertyChange, fireMultiplePropertiesChanged, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueHolder

public ValueHolder()

Constructs a ValueHolder with null as initial value.

ValueHolder

public ValueHolder(Object initialValue)

Constructs a ValueHolder with the given initial value. By default the old and new value are compared using #equals when firing value change events.

Parameters:

initialValue - the initial value

ValueHolder

public ValueHolder(Object initialValue,
           boolean checkIdentity)

Constructs a ValueHolder with the given initial value.

Parameters:

initialValue - the initial value

checkIdentity - true to compare the old and new value using ==, false to use #equals

ValueHolder

public ValueHolder(boolean initialValue)

Constructs a ValueHolder with the specified initial boolean value that is converted to a Boolean object.

Parameters:

initialValue - the initial boolean value

ValueHolder

public ValueHolder(double initialValue)

Constructs a ValueHolder with the specified initial double value that is converted to a Double object.

Parameters:

initialValue - the initial double value

ValueHolder

public ValueHolder(float initialValue)

Constructs a ValueHolder with the specified initial float value that is converted to a Float object.

Parameters:

initialValue - the initial float value

ValueHolder

public ValueHolder(int initialValue)

Constructs a ValueHolder with the specified initial int value that is converted to an Integer object.

Parameters:

initialValue - the initial int value

ValueHolder

public ValueHolder(long initialValue)

Constructs a ValueHolder with the specified initial long value that is converted to a Long object.

Parameters:

initialValue - the initial long value

Method Detail

getValue

public Object getValue()

Returns the observed value.

Returns:

the observed value

setValue

public void setValue(Object newValue)

Sets a new value. Fires a value change event if the old and new value differ. The difference is tested with == if isIdentityCheckEnabled answers true. The values are compared with #equals if the identity check is disabled.

Parameters:

newValue - the new value

isIdentityCheckEnabled

public boolean isIdentityCheckEnabled()

Answers whether this ValueHolder fires value change events if and only if the old and new value are not the same.

Returns:

true if the old and new value are compared using ==, false if the values are compared using #equals

setIdentityCheckEnabled

public void setIdentityCheckEnabled(boolean checkIdentity)

Sets the comparison that is used to check differences between the old and new value when firing value change events. This is the default setting that is used when changing the value via #setValue(Object). You can override this default setting by changing a value via #setValue(Object, boolean).

Parameters:

checkIdentity - true to compare the old and new value using ==, false to use #equals

setValue

public void setValue(Object newValue,
            boolean checkIdentity)

Sets a new value. Fires a value change event if the old and new value differ. The difference is tested with == if checkIdentity is true. The values are compared with #equals if the checkIdentiy parameter is set to false.

Unlike general bean property setters, this method does not fire an event if the old and new value are null.

Parameters:

newValue - the new value

checkIdentity - true to compare the old and new value using ==, false to use #equals