কমপ্যাক্ট ক্যানোনিকাল কনস্ট্রাক্টর (Compact Canonical Constructor)

public class Point {
    private final int x, y;
    public Point(int x, int y) { ... }
    public int getX() { return x; }
    public int getY() { return y; }
    // equals, hashCode, toString
}

class Square extends Shape {
    Square(double side) {
        super(side, side);
        // can't validate BEFORE super!
        if (side <= 0)
            throw new IAE("bad");
    }
}

// Verbose error class
public class ErrorResponse {
    private final int code;
    private final String message;
    // constructor, getters, equals,
    // hashCode, toString...
}