fxgl-variables-events

name	fxgl-variables-events
description	Manage reactive game state in FXGL — declare typed world variables in initGameVars, read/write/increment them via DSL, bind JavaFX UI properties to live variable values, register property-change listeners triggered at specific thresholds, fire and subscribe to custom events on the EventBus, use the built-in game timer (runOnce, runAtInterval), and create offline timers that persist between sessions. Use this skill when tracking score, lives, time, game flags, wiring HUD to game state, implementing event-driven logic, or scheduling delayed/recurring actions.
triggers	["game variable","initGameVars","EventBus","property binding","reactive","inc","geti","getip","onIntChangeTo","game timer","runOnce","runAtInterval","world properties","fire event"]
compatibility	Java 17+, FXGL 21.x
category	fxgl/state
tags	["fxgl","java","javafx","state","variables","events"]
metadata	{"author":"fxgl-skills","version":"1.0","fxgl-version":"21.1"}
allowed-tools	["Read","Write","Edit","Bash"]

FXGL Variables & Events

Declaring Variables

All variables must be declared in initGameVars. FXGL creates strongly-typed Property objects for each entry — use them for reactive UI bindings.

@Override
protected void initGameVars(Map<String, Object> vars) {
    vars.put("score",       0);       // → IntegerProperty
    vars.put("lives",       3);       // → IntegerProperty
    vars.put("health",      100.0);   // → DoubleProperty
    vars.put("hasShield",   false);   // → BooleanProperty
    vars.put("playerName",  "Hero");  // → StringProperty
    vars.put("currentLevel", 1);      // → IntegerProperty
    vars.put("inventory",   new ArrayList<Item>()); // → ObjectProperty<T>
}

Reading & Writing at Runtime

// Read
int    score   = geti("score");
double hp      = getd("health");
boolean shield = getb("hasShield");
String  name   = gets("playerName");
List<Item> inv = geto();   


set(,     );
set(, );
set(,  );


inc(,  +);
inc(,  -);
inc(, +);