Java By Comparison

Favor Optional Over Null

class Communicator {

    Connection connectionToEarth;

    void establishConnection() {
        // used to set connectionToEarth, but may be unreliable
    }

    Connection getConnectionToEarth() {
        return connectionToEarth;
    }
}

References that don’t point to an object point to the null reference instead. If you try to call a method on a null reference, you cause a NullPointerException. This is probably the most well-known exception in Java.

Using null references is fine for internal state where you have full control over how the reference is accessed. But exposing it makes the program fragile because every caller needs to check for null, which is something that people easily forget. This is what we’ve discussed ...