java-util-observer

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

  class SpellBook extends Observable {
  int spellSlotsRemaining, maxSpellSlots;
  List<List<Spell>> spellsAtLevel;
  }
  
  class SpellBookUI extends JPanel {
  ObservableListener<JTextField, SpellBook> 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);
  }
  }