| New file |
|---|
| 0,0 → 1,125 |
|---|
| package org.tela_botanica.del.client.utils; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| public class GwtObservable { |
| List<GwtObserver> observers = new ArrayList<GwtObserver>(); |
| |
| boolean changed = false; |
| |
| /** |
| * Constructs a new {@code Observable} object. |
| */ |
| public GwtObservable() { |
| super(); |
| } |
| |
| /** |
| * Adds the specified observer to the list of observers. If it is already |
| * registered, it is not added a second time. |
| * |
| * @param observer |
| * the Observer to add. |
| */ |
| public void addObserver(GwtObserver observer) { |
| if (observer == null) { |
| throw new NullPointerException(); |
| } |
| synchronized (this) { |
| if (!observers.contains(observer)) |
| observers.add(observer); |
| } |
| } |
| |
| /** |
| * Clears the changed flag for this {@code Observable}. After calling |
| * {@code clearChanged()}, {@code hasChanged()} will return {@code false}. |
| */ |
| protected void clearChanged() { |
| changed = false; |
| } |
| |
| /** |
| * Returns the number of observers registered to this {@code Observable}. |
| * |
| * @return the number of observers. |
| */ |
| public int countObservers() { |
| return observers.size(); |
| } |
| |
| /** |
| * Removes the specified observer from the list of observers. Passing null |
| * won't do anything. |
| * |
| * @param observer |
| * the observer to remove. |
| */ |
| public synchronized void deleteObserver(GwtObserver observer) { |
| observers.remove(observer); |
| } |
| |
| /** |
| * Removes all observers from the list of observers. |
| */ |
| public synchronized void deleteObservers() { |
| observers.clear(); |
| } |
| |
| /** |
| * Returns the changed flag for this {@code Observable}. |
| * |
| * @return {@code true} when the changed flag for this {@code Observable} is |
| * set, {@code false} otherwise. |
| */ |
| public boolean hasChanged() { |
| return changed; |
| } |
| |
| /** |
| * If {@code hasChanged()} returns {@code true}, calls the {@code update()} |
| * method for every observer in the list of observers using null as the |
| * argument. Afterwards, calls {@code clearChanged()}. |
| * <p> |
| * Equivalent to calling {@code notifyObservers(null)}. |
| */ |
| public void notifyObservers() { |
| notifyObservers(null); |
| } |
| |
| /** |
| * If {@code hasChanged()} returns {@code true}, calls the {@code update()} |
| * method for every Observer in the list of observers using the specified |
| * argument. Afterwards calls {@code clearChanged()}. |
| * |
| * @param data |
| * the argument passed to {@code update()}. |
| */ |
| public void notifyObservers(Object data) { |
| int size = 0; |
| GwtObserver[] arrays = null; |
| synchronized (this) { |
| if (hasChanged()) { |
| clearChanged(); |
| size = observers.size(); |
| arrays = new GwtObserver[size]; |
| observers.toArray(arrays); |
| } |
| } |
| if (arrays != null) { |
| for (GwtObserver observer : arrays) { |
| observer.update(this, data); |
| } |
| } |
| } |
| |
| /** |
| * Sets the changed flag for this {@code Observable}. After calling |
| * {@code setChanged()}, {@code hasChanged()} will return {@code true}. |
| */ |
| protected void setChanged() { |
| changed = true; |
| } |
| |
| } |