Module is.codion.common.core
Package is.codion.common.value

Class AbstractValue<T>

java.lang.Object
is.codion.common.value.AbstractValue<T>
Type Parameters:
T - the value type
All Implemented Interfaces:
Observable<T>, Observer<T>, Value<T>
Direct Known Subclasses:
AbstractComponentValue
public abstract class AbstractValue<T> extends Object implements Value<T>

An abstract Value implementation handling everything except the value itself.

The constructor parameter notify specifies whether this AbstractValue instance should call notifyListeners() each time the value is set (Value.Notify.SET) or only when it changes (Value.Notify.CHANGED), which is determined using Object.equals(Object).

Implementations that want to handle notifications manually should use the AbstractValue() or AbstractValue(Object) constructors.

  • Constructor Details

    • AbstractValue

      protected AbstractValue()

      Creates a nullable AbstractValue instance, which does not notify listeners.

    • AbstractValue

      protected AbstractValue(Value.Notify notify)
      Creates a nullable AbstractValue instance.
      Parameters:
      notify - specifies when to notify listeners

    • AbstractValue

      protected AbstractValue(@Nullable T nullValue)

      Creates an AbstractValue instance, which does not notify listeners.

      If nullValue is non-null, this AbstractValue instance will be non-nullable, meaning isNullable() returns false, get() is guaranteed to never return null and when set(Object) receives null it is automatically translated to nullValue.

      Parameters:
      nullValue - the value to use instead of null

    • AbstractValue

      protected AbstractValue(@Nullable T nullValue, Value.Notify notify)

      Creates an AbstractValue instance.

      If nullValue is non-null, this AbstractValue instance will be non-nullable, meaning isNullable() returns false, get() is guaranteed to never return null and when set(Object) receives null it is automatically translated to nullValue.

      Parameters:
      nullValue - the value to use instead of null
      notify - specifies when to notify listeners

  • Method Details

    • get

      public final @Nullable T get()
      Specified by:
      get in interface Observable<T>
      Returns:
      the value

    • set

      public final void set(@Nullable T value)
      Description copied from interface: Value
      Sets the value. Note that change listener notifications depend on the Value.Notify policy associated with this value.
      Specified by:
      set in interface Value<T>
      Parameters:
      value - the value
      See Also:

    • clear

      public final void clear()
      Description copied from interface: Value
      Clears this value, by setting it to null or the null value in case this is a non-null value.
      Specified by:
      clear in interface Value<T>

    • map

      public final void map(UnaryOperator<T> mapper)
      Description copied from interface: Value
      Sets a new value mapped from the current value. 
      Value<Integer> value = Value.value(0);

// increment the value by one
value.map(currentValue -> currentValue + 1);
      Specified by:
      map in interface Value<T>
      Parameters:
      mapper - maps from the current value to a new value

    • observable

      public Observable<T> observable()
      Specified by:
      observable in interface Value<T>
      Returns:
      a read-only Observable instance for this value

    • observer

      public final Observer<T> observer()
      Specified by:
      observer in interface Observable<T>
      Returns:
      an Observer notified each time the observed value may have changed

    • isNullable

      public final boolean isNullable()
      Description copied from interface: Observable
      If false then get() is guaranteed to never return null.
      Specified by:
      isNullable in interface Observable<T>
      Returns:
      true if this observable can be null

    • link

      public final void link(Value<T> originalValue)
      Description copied from interface: Value
      Creates a bidirectional link between this and the given original value, so that changes in one are reflected in the other. Note that after a call to this method this value is the same as originalValue.
      Specified by:
      link in interface Value<T>
      Parameters:
      originalValue - the original value to link this value to

    • unlink

      public final void unlink(Value<T> originalValue)
      Description copied from interface: Value
      Unlinks this value from the given original value
      Specified by:
      unlink in interface Value<T>
      Parameters:
      originalValue - the original value to unlink from this one

    • link

      public final void link(Observable<T> observable)
      Description copied from interface: Value
      Creates a unidirectional link between this value and the given observable, so that changes in the observable are reflected in this one. Note that after a call to this method the value of this value is the same as the observable.
      Specified by:
      link in interface Value<T>
      Parameters:
      observable - the observable to link this value to

    • unlink

      public final void unlink(Observable<T> observable)
      Description copied from interface: Value
      Unlinks this value from the given observable
      Specified by:
      unlink in interface Value<T>
      Parameters:
      observable - the observable to unlink

    • addValidator

      public final boolean addValidator(Value.Validator<? super T> validator)
      Description copied from interface: Value
      Adds a validator to this Value. Adding the same validator again has no effect.
      Specified by:
      addValidator in interface Value<T>
      Parameters:
      validator - the validator
      Returns:
      true if this value did not already contain the specified validator

    • removeValidator

      public final boolean removeValidator(Value.Validator<? super T> validator)
      Description copied from interface: Value
      Removes the given validator from this value
      Specified by:
      removeValidator in interface Value<T>
      Parameters:
      validator - the validator
      Returns:
      true if this value contained the specified validator

    • validate

      public final void validate(@Nullable T value)
      Description copied from interface: Value
      Validate the given value using all validators
      Specified by:
      validate in interface Value<T>
      Parameters:
      value - the value to validate

    • getValue

      protected abstract @Nullable T getValue()
      Returns the actual internal value.
      Returns:
      the value

    • setValue

      protected abstract void setValue(@Nullable T value)
      Sets the actual internal value.
      Parameters:
      value - the value

    • notifyListeners

      protected final void notifyListeners()
      Notifies listeners that the underlying value has changed or at least that it may have changed

    • createObservable

      protected Observable<T> createObservable()
      Returns:
      a new Observable instance representing this value