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package javafx.collections;

Interface that receives notifications of changes to an ObservableMap.
Type parameters:
<K> – the key element type
<V> – the value element type
Since:
JavaFX 2.0/**
 * Interface that receives notifications of changes to an ObservableMap.
 * @param <K> the key element type
 * @param <V> the value element type
 * @since JavaFX 2.0
 */
@FunctionalInterface
public interface MapChangeListener<K, V> {

    
An elementary change done to an ObservableMap.
Change contains information about a put or remove operation.
Note that put operation might remove an element if there was
already a value associated with the same key. In this case
wasAdded() and wasRemoved() will both return true.
Type parameters:
<K> – key type
<V> – value type
Since:
JavaFX 2.0/**
     * An elementary change done to an ObservableMap.
     * Change contains information about a put or remove operation.
     * Note that put operation might remove an element if there was
     * already a value associated with the same key. In this case
     * wasAdded() and wasRemoved() will both return true.
     *
     * @param <K> key type
     * @param <V> value type
     * @since JavaFX 2.0
     */
    public static abstract class Change<K, V> {

        private final ObservableMap<K,V> map;

        
Constructs a change associated with a map.
Params:
map – the source of the change/**
         * Constructs a change associated with a map.
         * @param map the source of the change
         */
        public Change(ObservableMap<K, V> map) {
            this.map = map;
        }

        
An observable map that is associated with the change.
Returns:
the source map/**
         * An observable map that is associated with the change.
         * @return the source map
         */
        public ObservableMap<K, V> getMap() {
            return map;
        }

        
If this change is a result of add operation.
Returns:
true if a new value (or key-value) entry was added to the map/**
         * If this change is a result of add operation.
         * @return true if a new value (or key-value) entry was added to the map
         */
        public abstract boolean wasAdded();

        
If this change is a result of removal operation.
Note that an element might be removed even as a result of put operation.
Returns:
true if an old value (or key-value) entry was removed from the map/**
         * If this change is a result of removal operation.
         * Note that an element might be removed even as a result of put operation.
         * @return true if an old value (or key-value) entry was removed from the map
         */
        public abstract boolean wasRemoved();

        
A key associated with the change.
If the change is a remove change, the key no longer exist in a map.
Otherwise, the key got set to a new value.
Returns:
the key that changed/**
         * A key associated with the change.
         * If the change is a remove change, the key no longer exist in a map.
         * Otherwise, the key got set to a new value.
         * @return the key that changed
         */
        public abstract K getKey();

        
Get the new value of the key. Return null if this is a removal.
Returns:
the value that is now associated with the key/**
         * Get the new value of the key. Return null if this is a removal.
         * @return the value that is now associated with the key
         */
        public abstract V getValueAdded();

        
Get the old value of the key. This is null if and only if the value was
added to the key that was not previously in the map.
Returns:
the value previously associated with the key/**
         * Get the old value of the key. This is null if and only if the value was
         * added to the key that was not previously in the map.
         * @return the value previously associated with the key
         */
        public abstract V getValueRemoved();

    }

    
Called after a change has been made to an ObservableMap.
This method is called on every elementary change (put/remove) once.
This means, complex changes like keySet().removeAll(Collection) or clear()
may result in more than one call of onChanged method.
Params:
change – the change that was made/**
     * Called after a change has been made to an ObservableMap.
     * This method is called on every elementary change (put/remove) once.
     * This means, complex changes like keySet().removeAll(Collection) or clear()
     * may result in more than one call of onChanged method.
     *
     * @param change the change that was made
     */
    void onChanged(Change<? extends K,? extends V> change);
}