java-util-observer/README.md

Observable - Disjoint UI updates for complex objects

This library exists to combine together two objectives in updating UI objects: 1) Be able to 'remotely' notify UI objects about updates without having to iterate through the entire component tree. 2) Allow editting of a shared resource from multiple potential call sites without needing a controller object that holds references to every single interested view.

This is a useful construct in the situation where you have a large number of fixed GUI components in a program (for example, rendering the various statistics of a Dungeons and Dragons (c) character), because the connections are made anonymously.

Requirements

• Java 7
• org.leumasjaffe.event

• Google Guava

  Installation

  Steps

  1) Download or clone this repository. 2) mvn install 3) Add the below block to your pom.xml

  Maven Artifact

  <dependency>
  <groupId>org.leumasjaffe</groupId>
  <artifactId>observable</artifactId>
  </dependency>
  

  Example Code Snippets

  ``` java class SpellBook extends Observable { int spellSlotsRemaining, maxSpellSlots; List> spellsAtLevel; }

class SpellBookUI extends JPanel { ObservableListener listener; SpellBookUI(SpellBook model) {

JTextField spellsRemaining = new JTextField();
add(spellsRemaining);

// Set up a listener to anonymously update when model changes
listener = new ObservableListener<>(spellsRemaining, (text, book) -> {
  text.setText(book.getSpellSlotsRemaining());
});

// Automatically invokes callback, setting the text field
listener.setObserved(model);

} }

class CastSpellCommand { SpellBook book; void cast(Spell spell) {

// ...
--book.spellSlotsRemaining;
// Will automatically invoke the code in the ObservableListener above
ObserverDispatch.notifySubscribers(book);

} } ```