Custom State Objects

The built-in CellState holds a key (String) and a value (any Object), which is sufficient for simple automata such as a binary-state Game of Life. For more complex simulations — where each cell might carry temperature, pressure, material type, or any other domain-specific data — you can extend CellState with a custom class.

Overview

Define your custom status by extending CellState and adding fields.
Cast in transition — in your executor, cast cell.getCurrentStatus() to your subclass to access the extra fields.
Use your custom status as the default status and in the initial condition list.

Example: Custom Status for Game of Life

The GoLStatus class wraps a simple boolean isAlive field and produces a readable toString() so the grid renders clearly.

public class GoLStatus extends CellState {

    public boolean isAlive;

    public GoLStatus(boolean isAlive) {
        super("GoLStatus", isAlive);
        this.isAlive = isAlive;
    }

    @Override
    public String toString() {
        return isAlive ? "1 " : "0 ";
    }
}

The Rule

Cast currentStatus to GoLStatus inside transition:

public class GoLCustomRule extends CellularAutomataRule {

    @Override
    public Cell transition(Cell cell, List<Cell> neighbors) {
        long aliveCount = neighbors.stream()
            .filter(n -> ((GoLStatus) n.getCurrentStatus()).isAlive)
            .count();

        boolean isAlive = ((GoLStatus) cell.getCurrentStatus()).isAlive;
        boolean nextAlive = (!isAlive && aliveCount == 3)
                          || (isAlive && (aliveCount == 2 || aliveCount == 3));

        Cell next = new Cell(
            new GoLStatus(nextAlive),
            cell.getCol(), cell.getRow()
        );
        return next;
    }
}

The Application Entry Point

Use GoLStatus as the defaultStatus and in the initial condition:

GoLStatus dead = new GoLStatus(false);

List<Cell> seed = new ArrayList<>();
seed.add(new Cell(new GoLStatus(true), 1, 1));
seed.add(new Cell(new GoLStatus(true), 1, 2));
seed.add(new Cell(new GoLStatus(true), 1, 3));

CellularAutomataConfiguration config = new CellularAutomataConfigurationBuilder()
    .setWidth(10).setHeight(10)
    .setTotalIterations(5)
    .setDefaultStatus(dead)
    .setNeighborhoodType(NeighborhoodType.MOORE)
    .setInitalState(seed)
    .build();

CellularAutomata ca = new CellularAutomata(config);
ca = new GoLCustomRule().run(ca);
System.out.println(ca);

Example: Numeric State (Heat Diffusion)

For simulations that require a numeric quantity per cell:

public class HeatStatus extends CellState {

    public double temperature;

    public HeatStatus(double temperature) {
        super("heat", temperature);
        this.temperature = temperature;
    }

    @Override
    public String toString() {
        return String.format("%.1f ", temperature);
    }
}

Use it in an executor that averages neighbors’ temperatures:

public class HeatDiffusionRule extends CellularAutomataRule {

    @Override
    public Cell transition(Cell cell, List<Cell> neighbors) {
        double avgTemp = neighbors.stream()
            .mapToDouble(n -> ((HeatStatus) n.getCurrentStatus()).temperature)
            .average()
            .orElse(0.0);

        double current = ((HeatStatus) cell.getCurrentStatus()).temperature;
        double next = (current + avgTemp) / 2.0;

        return new Cell(new HeatStatus(next), cell.getCol(), cell.getRow());
    }
}

Tips

Two CellState values are equal when both key and value are equal. If you store mutable objects in value, override equals / hashCode in your subclass for correct comparison semantics.
The value field accepts any Object, so you can store a Map, a POJO, a numeric type, or any domain object you need.
Override toString() in your custom status to get useful output from CellularAutomata.toString().
For automata that accumulate quantities between steps (e.g., flows, counters), pair the custom status with the refinements hook for pre-processing.