Lazy - https://dzone.com/articles/be-lazy-with-java-8

Lazy.java

public final class Lazy<T> {
    private volatile T value;
    public T getOrCompute(Supplier<T> supplier) {
        final T result = value; // Just one volatile read 
        return result == null ? maybeCompute(supplier) : result;
    }
    private synchronized T maybeCompute(Supplier<T> supplier) {
        if (value == null) {
            value = requireNonNull(supplier.get());
        }
        return value;
    }
}

Point.java

public class Point {
    private final int x, y;
    private final Lazy<String> lazyToString;
    public Point(int x, int y) {
        this.x = x; 
        this.y = y;
        lazyToString = new Lazy<>();
    }
    @Override
    public String toString() {
        return lazyToString.getOrCompute( () -> "(" + x + ", " + y + ")");
    }
}